The Danish health care system and epidemiological research: from health care contacts to database records

Incidence of late recurrence and second primary cancers 5-10 years after non-metastatic colorectal cancer

The fraction of patients who are cancer-free survivors 5 years after curative-intended surgery for colorectal cancer (CRC) is increasing, suggesting that extending surveillance beyond 5 years may be indicated. Here we estimate the incidence of late recurrence, metachronous CRC, and second primary cancers 5-10 years postoperative. All patients resected for UICC stage I-III CRC in Denmark through 2004-2013 were identified. Through individual-level linkage of nationwide health registry data, recurrence status was determined using a validated algorithm. Cancer-free survivors 5 years after surgery, were included. Cumulative incidence functions (CIF) of late recurrence, metachronous CRC, and second primary cancer 5-10 years postoperative were constructed. Subdistribution hazards ratios (sHR) were computed using Fine-Gray regression. Among 8883 patients, 370 developed late recurrence (5-10-year CIF = 4.1%, 95%CI: 3.7%-4.6%), 270 metachronous CRC (5-10-year CIF = 3.0%, 95%CI: 2.7%-3.4%), and 635 a second primary cancer (5-10-year CIF = 7.2%, 95%CI: 6.7%-7.7%). The risk of late recurrence was reduced for patients operated in 2009-2013 compared to 2004-2008 (2.9% vs. 5.6%, sHR = 0.52, 95% CI: 0.42-0.65). The risk of metachronous CRC was likewise reduced from 4.1% to 2.1% (sHR = 0.50, 95%CI: 0.39-0.65). While the risk of second primary cancer did not change between 2009-2013 and 2004-2008 (7.1% vs. 7.1%, sHR = 0.98, 95% CI: 0.84-1.15). Using nation-wide 10-year follow-up data, we document that the incidences of late recurrence and metachronous CRC are low and decreasing from 2004 to 2013. Thus, despite increasing numbers of long-term cancer survivors, the data do not advocate for extending CRC-specific surveillance beyond 5 years.

Fifteen-year temporal changes in rates of acute kidney injury among children in Denmark

BACKGROUND

We aimed to examine temporal changes in the annual rate of acute kidney injury (AKI) in Danish children and associated changes in patient characteristics including potential underlying risk factors.

METHODS

In this population-based cohort study, we used plasma creatinine measurements from Danish laboratory databases to identify AKI episodes in children aged 0-17 years from 2007 to 2021. For each child, the first AKI episode per calendar year was included. We estimated the annual crude and sex- and age-standardized AKI rate as the number of children with an AKI episode divided by the total number of children as reported by census numbers. Using Danish medical databases, we assessed patient characteristics including potential risk factors for AKI, such as use of nephrotoxic medication, surgery, sepsis, and perinatal factors.

RESULTS

In total, 14,200 children contributed with 16,345 AKI episodes over 15 years. The mean annual AKI rate was 148 (95% CI: 141-155) per 100,000 children. From 2007 to 2021, the annual AKI rate demonstrated minor year-to-year variability without any discernible overall trend. The highest AKI rate was recorded in 2007 at 174 (95% CI: 161-187) per 100,000 children, while the lowest rate occurred in 2012 at 129 (95% CI: 118-140) per 100,000 children. In 2021, the AKI rate was 148 (95% CI: 141-155) per 100,000 children. Characteristics of children with AKI were similar throughout the study period.

CONCLUSION

The rate of AKI among Danish children was stable from 2007 to 2021 with little variation in patient characteristics over time.

Cost of out-of-hospital cardiac arrest survivors compared with matched control groups

INTRODUCTION

Societal costs of out-of-hospital cardiac arrest (OHCA) survivors may be extensive due to high health care utilization and sick leave. Knowledge of the costs of OHCA survivors may guide decision-makers to prioritize health resources.

AIM

The aims of the study were to evaluate the costs of OHCA survivors from a societal perspective, and to compare these costs to the costs of individuals with non-cardiac arrest myocardial infarction (MI) and individuals with no cardiac disease (non-CD).

METHODS

From the Danish OHCA Registers, survivors, with a cardiac arrest between 2005-2018 were identified. Each case was assigned one MI control and one non-CD control, matched on gender and age. Based on register data, costs of healthcare utilization, sick leave, vocational rehabilitation, disability pension and other social benefits one year before event and five years after, were estimated.

RESULTS

In total 5,646 OHCA survivors were identified with associated control groups. The mean costs for OHCA survivors during the 6-year period were €119,106 (95%CI: 116,297-121,916), with €83,472 (95%CI: 81,392-85,552) being healthcare costs. Mean costs of OHCA survivors were €49,132 higher than the MI-control group and €100,583 higher than the non-CD control group.

CONCLUSIONS

Total costs of OHCA survivors were considerably higher than costs of MI- and non-CD controls. Hospital costs were highest during the first year after event, and work inability during the second to fifth year with sick leave and later disability pension as main burdens.

Changes in Symptoms and General Well-being After Reversal of Roux-en-Y Gastric Bypass: A Questionnaire Survey

PURPOSE

After Roux-en-Y gastric bypass (RYGB), few patients develop severe complications, which ultimately may require reversal of RYGB. We aimed to examine the effect of reversal of RYGB on symptoms and well-being.

MATERIALS AND METHODS

Via contact to medical and surgical departments treating patients with RYGB, we identified 18 patients, who had undergone reversal, 2009-2019. We conducted a Danish, nationwide questionnaire survey concerning symptoms before and after reversal of the RYGB including the patients' own perceptions of their well-being.

RESULTS

Fourteen patients responded to the questionnaire (86% female; median age at RYGB, 36.2 years [IQR, 30.9-38.6 years]). The median time from RYGB to reversal was 5.8 years (IQR, 5.1-7.5 years). After RYGB, 13 patients (93%) reported abdominal pain, while 12 patients still had abdominal pain after reversal. Six out of 11 patients (45%) reported complete remission of dumping/post-bariatric hypoglycemia (PBH) after reversal. Malabsorption disappeared in 10 out of 11 patients (90%). Reversal had minor effect on neuropathy. The median weight loss from RYGB was 61 kg (IQR, 56-75 kg), while the median weight regain after reversal was 30 kg (IQR, 13-46 kg). Regarding the well-being, 72 of the patients felt better or much better after reversal.

CONCLUSION

In total, 72% of the patients felt better or much better after reversal of RYGB, though some still had RYGB-related symptoms. The reversal relieved dumping/PBH and malabsorption, but not abdominal pain and neuropathy. Finally, half of the weight loss was regained after reversal. Reversal of RYGB may be an option in highly selected cases.

Inhaled corticosteroid treatment and pneumonia in patients with chronic obstructive pulmonary disease - nationwide development from 1998 to 2018

Background

A decreasing use of inhaled corticosteroids (ICS) in patients with a hospital-registered diagnosis of chronic obstructive pulmonary disease (COPD) has recently been documented in Denmark. ICS treatment is not recommended in patients with high pneumonia risk, and we aimed to assess the development of ICS treatment in relation to pneumonia occurrence.

Methods

Annual nationwide register-based cross-sectional studies from 1998 to 2018 including all patients ≥40 years of age with a hospital-registered ICD-10 diagnosis of COPD on the 31st of December each year. We calculated the annual proportion of patients with at least one outpatient pneumonia (redeemed prescription of relevant antibiotics) or pneumonia hospitalization (hospitalization or ER visit), and stratified by ICS dose (No ICS, low dose, medium dose, or high dose).

Results

The study population increased from 35,656 patients in 1998 to 99,057 patients in 2018. The annual proportion of patients experiencing a pneumonia decreased from 69.4% to 55.2%. The proportion of patients with at least one outpatient pneumonia, but no hospitalization, decreased (59.2% to 46.2%). The overall proportion of patients with at least one pneumonia hospitalization remained unchanged (10.2% to 9.0%), but this proportion increased in patients in high dose ICS (9.9% to 14.6%). The overall proportion of patients in high dose treatment decreased (12.7% to 5.7%), but not in patients with pneumonia hospitalization (16.5% to 15.1).

Conclusions

Our study demonstrates a nationwide decrease from 1998 to 2018 in the proportion of patients who redeemed a prescription for antibiotics used mainly for respiratory tract infections, which may reflect a decrease in the number of outpatient pneumonias. This decrease was largely caused by an increase in the number of patients without pneumonia. No differences over time were seen regarding hospitalization-requiring pneumonia. High dose ICS treatment was unchanged in patients with hospitalization-requiring pneumonia.

Urban-rural and socio-economic differences in inhaled corticosteroid treatment for chronic obstructive pulmonary disease: A nationwide register-based cross-sectional study

BACKGROUND

Urban-rural disparities within chronic obstructive pulmonary disease (COPD) have been documented in USA, but not in Europe. Inhaled corticosteroids (ICS) are widely used in COPD despite strict recommendations. We aimed to investigate urban-rural and socioeconomic differences in ICS treatment for COPD.

METHODS

A Danish nationwide register-based cross-sectional study. All patients alive on the December 31, 2018 with a J44 ICD-10 diagnosis code (COPD) were included (99,057 patients). Daily average ICS dose was calculated from the accumulated ICS use during 2018 based on redeemed prescriptions. Patients were divided into groups: No ICS, low dose ICS, medium dose ICS, high dose ICS. A multinomial logistic regression model including educational level, co-habitation status, age, and sex was performed with "No ICS" as reference group.

RESULTS

Compared to capital municipalities, living in other municipality types was associated with an increased probability of receiving medium and high dose ICS treatment, and increasing odds ratios (ORs) were seen with increasing ICS dose (medium dose ICS: ORs between 1.31 (95 % confidence interval (CI) 1.24-1.38) and 1.35 (95%CI 1.28-1.41), high dose ICS: ORs between 1.73 (95%CI 1.59-1.88) and 1.80 (95%CI 1.68-1.92)). Patients had increased probability of receiving ICS treatment if they were female, were co-habiting, or had completed only primary education.

CONCLUSION

Patients with a hospital-registered COPD diagnosis in non-capital municipalities receive more ICS, and in higher doses, compared to patients in capital municipalities. This is the first study to confirm that such urban-rural differences exist in Europe, and further research on this area is warranted.

Evaluation of Left Truncation and Censoring When Changing the Use of the International Classification of Diseases Eighth Revision Codes to Tenth Revision Codes in the Danish National Patient Registry

Purpose

In the Danish National Patient Registry (DNPR), covering all Danish hospitals and widely used in research, diseases have been recorded using International Classification of Diseases (ICD) codes, transitioning from the Eighth to the Tenth revision in 1994. Uncertainty exists regarding whether including ICD-8 codes alongside ICD-10 is needed for complete disease identification. We assessed the extent of left-truncation and left-censoring in the DNPR arising from omitting ICD-8 codes.

Patients and Methods

We sampled 500,000 Danes ≥40 years of age in 1995, 2010, and 2018. From the DNPR, we identified cardiovascular, endocrine, gastrointestinal, neurological, pulmonary, rheumatic, and urogenital diseases as well as fractures. We obtained the number of people with a disease recorded with ICD-8 codes only (ie, the ICD-8 record would be left-truncated by not using ICD-8 codes), ICD-8 plus ICD-10 codes (ie, the ICD-8 record would be left-censored by not using ICD-8 codes), and ICD-10 codes only. For each ICD group, we calculated the proportion of people with the disease relative to the total sample (ie, 500,000 people) and the total number of people with the disease across all ICD groups.

Results

Overall, the left-truncation issue decreased over the years. Relative to all people with a disease, the left-truncated proportion was for example 59% in 1995 and <2% in 2018 for diabetes mellitus; 93% in 1995, and 54% in 2018 for appendicitis. The left-truncation issue increased with age group for most diseases. The proportion of disease records left-censored by not using ICD-8 codes was generally low but highest for chronic diseases.

Conclusion

The left-truncation issue diminished over sample years, particularly for chronic diseases, yet remained rather high for selected surgical diseases. The left-truncation issue increased with age group for most diseases. Left-censoring was overall a minor issue that primarily concerned chronic diseases.

Incidence and Prevalence of Fibrous Dysplasia/McCune-Albright Syndrome: A Nationwide Registry-Based Study in Denmark

CONTEXT

Fibrous dysplasia/McCune-Albright syndrome (FD/MAS) is a rare genetic disorder. Incidence and prevalence are not well-studied. Epidemiological research is complicated by the rarity of FD/MAS, absence of registries, heterogeneous presentation, and possibly asymptomatic phenotype. FD/MAS may present with FGF23-mediated hypophosphatemia, of which the epidemiology is also unclear.

OBJECTIVE

Evaluate incidence and prevalence of FD/MAS and FD/MAS-related hypophosphatemia.

METHODS

This cohort study based on the nationwide Danish National Patient Registry from 1995-2018, included patients identified by ICD-10 codes M85.0 (monostotic FD [MFD]) and Q78.1 (polyostotic FD [PFD]/MAS). Incidence rates and prevalence were calculated and stratified by sex, age, calendar period, and diagnosis code. Cases were screened for FD-associated hypophosphatemia by diagnosis code E.83 (disorder of mineral metabolism) and dispatched vitamin D analogues.

RESULTS

A total of 408 patients were identified, 269 with MFD (66%), 139 with PFD/MAS (34%), comparable between sexes. Incidence of FD/MAS demonstrated increasing secular trend with a rate of 3.6 per 1 000 000 person-years (95% CI: 2.9, 4.5) in 2015-2018. Incidence peaked between age 11 and 20. Prevalence of FD/MAS increased over time to 61.0 (95% CI: 54.6, 67.4) per 1 000 000 persons in 2018. The incidence rate of MFD was 1.5-fold that of PFD/MAS in the first decade, rising to 2.5-fold in the last decade. No FD/MAS cases were registered with diagnosis code or treatment for hypophosphatemia.

CONCLUSION

FD/MAS is rare, diagnosis peaks during adolescence without sex predominance, and MFD is most prevalent. Hypophosphatemia may be underdiagnosed and undertreated, or it may be underregistered, comparing this study to literature.

Identification of patients' smoking status using an explainable AI approach: a Danish electronic health records case study

BACKGROUND

Smoking is a critical risk factor responsible for over eight million annual deaths worldwide. It is essential to obtain information on smoking habits to advance research and implement preventive measures such as screening of high-risk individuals. In most countries, including Denmark, smoking habits are not systematically recorded and at best documented within unstructured free-text segments of electronic health records (EHRs). This would require researchers and clinicians to manually navigate through extensive amounts of unstructured data, which is one of the main reasons that smoking habits are rarely integrated into larger studies. Our aim is to develop machine learning models to classify patients' smoking status from their EHRs.

METHODS

This study proposes an efficient natural language processing (NLP) pipeline capable of classifying patients' smoking status and providing explanations for the decisions. The proposed NLP pipeline comprises four distinct components, which are; (1) considering preprocessing techniques to address abbreviations, punctuation, and other textual irregularities, (2) four cutting-edge feature extraction techniques, i.e. Embedding, BERT, Word2Vec, and Count Vectorizer, employed to extract the optimal features, (3) utilization of a Stacking-based Ensemble (SE) model and a Convolutional Long Short-Term Memory Neural Network (CNN-LSTM) for the identification of smoking status, and (4) application of a local interpretable model-agnostic explanation to explain the decisions rendered by the detection models. The EHRs of 23,132 patients with suspected lung cancer were collected from the Region of Southern Denmark during the period 1/1/2009-31/12/2018. A medical professional annotated the data into 'Smoker' and 'Non-Smoker' with further classifications as 'Active-Smoker', 'Former-Smoker', and 'Never-Smoker'. Subsequently, the annotated dataset was used for the development of binary and multiclass classification models. An extensive comparison was conducted of the detection performance across various model architectures.

RESULTS

The results of experimental validation confirm the consistency among the models. However, for binary classification, BERT method with CNN-LSTM architecture outperformed other models by achieving precision, recall, and F1-scores between 97% and 99% for both Never-Smokers and Active-Smokers. In multiclass classification, the Embedding technique with CNN-LSTM architecture yielded the most favorable results in class-specific evaluations, with equal performance measures of 97% for Never-Smoker and measures in the range of 86 to 89% for Active-Smoker and 91-92% for Never-Smoker.

CONCLUSION

Our proposed NLP pipeline achieved a high level of classification performance. In addition, we presented the explanation of the decision made by the best performing detection model. Future work will expand the model's capabilities to analyze longer notes and a broader range of categories to maximize its utility in further research and screening applications.

DARE-ISC model for prediction of 1-year ischaemic stroke risk in the general population and atrial fibrillation patients: a Danish nationwide cohort study

OBJECTIVES

To develop a risk assessment model (DAnish REgister Ischaemic Stroke Classifier, DARE-ISC) for predicting 1-year primary ischaemic stroke/systemic embolism (SE) in the general population. Secondly, to validate the accuracy DARE-ISC in atrial fibrillation (AF) patients where well-established models and risk scores exist.

DESIGN

Retrospective cohort study. DARE-ISC was developed using gradient boosting decision trees with information from 375 covariates including baseline information on relevant diagnoses, demographic characteristics, registered health-services, lifestyle-related covariates, hereditary stroke components, drug prescriptions and stress proxies.

SETTING

Danish nationwide registries.

PARTICIPANTS

All Danish individuals aged ≥18 from 2010 to 2017 (n=35 519 348 person-years). The model was trained on the 2010-2016 cohorts with validation in the 2017 cohort.

PRIMARY AND SECONDARY OUTCOME MEASURES

Model optimisation and validation were performed through comparison of the area under the receiver operating characteristic curve (AUC) and average precision scores. Additionally, the relative importance of the model covariates was derived using SHAP values.

RESULTS

DARE-ISC had an AUC (95% CI) of 0.874 (0.871 to 0.876) in the general population. In AF patients, DARE-ISC was superior to the GARFIELD-AF risk model and CHA2DS2-VASc score with AUC of 0.779 (95% CI 0.75 to 0.806), 0.704 (95% CI 0.674 to 0.732) and 0.681 (95% CI 0.652 to 0.709), respectively. Furthermore, in AF patients, DARE-ISC had an average threefold and fourfold higher ratio of correctly identified strokes compared with the GARFIELD-AF risk model and CHA2DS2-VASc score, as indicated by average precision scores of 0.119, 0.041 and 0.034, respectively.

CONCLUSIONS

DARE-ISC had a very high stroke prediction accuracy in the general population and was superior to the GARFIELD-AF risk model and CHA2DS2-VASc score for predicting ischaemic stroke/SE in AF patients.

Trends in the Use of Medications for Secondary Ischemic Stroke Prevention in Denmark, 2005-2021

BACKGROUND AND OBJECTIVES

Understanding trends in the use of medications for secondary stroke prevention is crucial for identifying areas for improvement in stroke care. We examined the use of lipid-lowering, antihypertensive, glucose-lowering, oral anticoagulant, and antiplatelet medications after ischemic stroke hospitalization, from 2005 to 2021.

METHODS

Using nationwide registries in Denmark, we identified a cohort of patients discharged from hospital with a first-time or recurrent ischemic stroke (N = 150,744). Stratified by calendar year, we ascertained the 180-day probability of filling a prescription for the abovementioned medications after discharge. We further assessed factors associated with medication use.

RESULTS

From 2005 to 2021, lipid-lowering medication use increased from 58.3% to 82.0%; atorvastatin use rose from 2.1% to 64.8% and simvastatin use decreased from 55.7% to 8.6%. Antihypertensive medication use remained stable, at approximately 89%, and various antihypertensive classes were used comparably. Glucose-lowering medication use increased from 71.5% in 2005 to 84.1% in 2021, driven primarily by an increase in metformin use (from 28.0% to 59.5%). Use of glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter-2 inhibitors continually increased (from 1.7% to 17.5% and from 0.5% to 17.3%, respectively) between 2015 and 2021. Anticoagulant medication use rose from 45.9% in 2005 to 87.0% in 2021, primarily because of increased use of direct oral anticoagulant medications starting around 2010 and a decline in warfarin use. Antiplatelet use remained consistently high, at approximately 95%. Trends were consistent across subgroups of interest; however, overall medication use was lower in older patients (65 years and older), patients with severe stroke, and patients with neurologic and psychiatric comorbidities.

DISCUSSION

Despite increasing trends in the use of 3 of 5 medication classes, the overall use of lipid-lowering, glucose-lowering, and oral anticoagulant medications was somewhat lower than expected according to clinical guidelines, particularly among older patients with more severe stroke and other comorbidities. The relatively low use in these subgroups may signify appropriate clinical decision making in consideration of frequent contraindications and reduced life expectancy or highlight potential areas of improvement for the care of patients with recent ischemic stroke.

VEGF Inhibition Associates With Decreased Risk of Mortality in Patients With Neovascular Age-related Macular Degeneration

Purpose

Controversy exists regarding the systemic safety of intravitreal VEGF inhibitors in the treatment of neovascular age-related macular degeneration (nAMD). We aimed to investigate the potential impact of VEGF inhibitor treatment on the risk of all-cause mortality and cardiovascular disease (CVD) among patients with nAMD.

Design

A nationwide register-based cohort study with 16 years follow-up.

Participants

Patients with nAMD exposed with VEGF inhibitors (n = 37 733) and unexposed individuals without nAMD (n = 1 897 073) aged ≥ 65 years residing in Denmark between January 1, 2007, and December 31, 2022.

Methods

Cox proportional hazards analysis was conducted to assess the effect of intravitreal VEGF inhibitor treatment on all-cause mortality and incident CVD.

Main Outcome Measures

In a predefined analysis plan we defined primary outcomes as hazard ratios (HRs) of all-cause mortality and a composite CVD endpoint in patients with nAMD treated with VEGF inhibitors compared with individuals without nAMD. The secondary outcomes encompassed analyses that explored the impact of the number of doses and the association between exposure and outcome over a specific time period.

Results

Overall, 63.7% of patients with nAMD were women with an average age of 69.9 years (interquartile range 65.0-76.0 years). Patients exposed to VEGF inhibitors demonstrated a reduced risk of all-cause mortality compared with individuals without nAMD (HR, 0.79; 95% confidence interval [CI], 0.78-0.81), and an increased risk of composite CVD (HR, 1.04; 95% CI, 1.01-1.07). The decreased risk of all-cause mortality persisted, but there was no significant association between VEGF inhibitor treatment and CVD when patients with nAMD were grouped by the number of doses or considered exposed within 60 days postinjection.

Conclusions

Our study revealed a decreased risk of all-cause mortality and a 4% increased risk of CVD among patients with nAMD exposed with VEGF inhibitors. The decreased risk of mortality is unlikely to be directly pathophysiologically related to VEGF inhibitor treatment. Instead, we speculate that patients undergoing VEGF inhibitor treatment are, on average, individuals in good health with adequate personal resources. Therefore, they also have a higher likelihood of overall survival. These findings strongly support the safety of VEGF inhibitor treatment in terms of all-cause mortality and CVD among patients with nAMD.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Influence of multimorbidity and socioeconomic position on long-term healthcare utilization and prognosis in patients after cardiac resynchronization therapy implantation

Aims

We aimed to investigate the influence of socioeconomic position (SEP) and multimorbidity on cross-sectional healthcare utilization and prognosis in patients after cardiac resynchronization therapy (CRT) implantation.

Methods and results

We included first-time CRT recipients with left ventricular ejection fraction ≤35% implanted between 2000 and 2017. Data on chronic conditions, use of healthcare services, and demographics were obtained from Danish national administrative and health registries. Healthcare utilization (in- and outpatient hospitalizations, activities in general practice) was compared by multimorbidity categories and SEP by using a negative binomial regression model. The association between SEP, multimorbidity, and prognostic outcomes was analysed using Cox proportional hazards regression. We followed 2007 patients (median age of 70 years), 79% were male, 75% were on early retirement or state pension, 37% were living alone, and 41% had low education level for a median of 5.2 [inter-quartile range: 2.2-7.3) years. In adjusted regression models, a higher number of chronic conditions were associated with increased healthcare utilization. Both cardiovascular and non-cardiovascular hospital contacts were increased. Patients with low SEP had a higher number of chronic conditions, but SEP had limited influence on healthcare utilization. Patients living alone and those with low educational level had a trend towards a higher risk of all-cause mortality [adjusted hazard ratio (aHR): 1.17, 95% confidence interval (CI) 1.03-1.33, and aHR 1.09, 95% CI 0.96-1.24).

Conclusion

Multimorbidity increased the use of cross-sectional healthcare services, whereas low SEP had minor influence on the utilizations. Living alone and low educational level showed a trend towards a higher risk of mortality after CRT implantation.

High Incidence of Cardiovascular Disease in Patients With Oesophageal Cancer-A Registry-Based Cohort Study

BACKGROUND

The cardiovascular disease (CVD) burden among patients with oesophageal cancer (EC) treated with curative intent is unclear.

AIM

To determine CVD incidence and all-cause mortality in patients with EC.

METHOD

Danish national health registries were used to identify patients diagnosed with primary EC between 2008 and 2018. Each EC patient was matched with 10 individuals from the general population. The primary endpoint was a CVD hospital contact (CVD-HC), either admission or outpatient contact. Cox proportional hazard regression models were used to compare the risk of incident CVD-HCs between the cohorts.

RESULTS

The study included 1,525 patients with EC and 15,250 individuals from the general population. Patients with EC had a post-diagnosis one-year adjusted hazard ratio (HR) of CVD-HC of 6.1 (95% confidence intervals [CIs] 5.6-6.8) compared with the general population. During the next nine years, the risk of CVD-HC was comparable between the two cohorts, with an adjusted HR of 1.0 (95% CI 0.9-1.3). Patients with EC, and particularly those with prevalent CVD, had a high risk of atrial fibrillation, ischaemic heart disease, and venous thromboembolism within the first year after EC diagnosis. Prevalent CVD among patients with EC was not associated with higher mortality.

CONCLUSIONS

CVD morbidity was transiently increased in the first year following EC diagnosis compared with the general population. All-cause mortality risks were high but did not appear to be affected by prevalent CVD. The very high risk of CVD in patients with primary EC to be treated with curative intent calls for healthcare initiatives to advance preventive and post-treatment strategies.

Risk and adverse clinical outcomes of thrombocytopenia among patients with solid tumors-a Danish population-based cohort study

BACKGROUND

Knowledge about thrombocytopenia among patients with solid tumors is scarce. We examined the risk of thrombocytopenia among patients with solid tumors and its association with adverse outcomes.

METHODS

Using Danish health registries, we identified all patients with incident solid tumors from 2015-2018 (n = 52,380) and a platelet count measurement within 2 weeks prior to or on their cancer diagnosis date. The risk of thrombocytopenia was categorized as grades 0 (any platelet count × 109/L): <150; 1: <100; 2: <75; 3: <50; 4: <25, and 5: <10. To study the outcomes, each patient with thrombocytopenia was matched with up to five cancer patients without thrombocytopenia by age, sex, cancer type, and stage. Cox regression was used to compute hazard ratios (HRs) of bleeding, transfusion, or death, adjusting for confounding factors.

RESULTS

The 1-year risk of thrombocytopenia was 23%, increasing to 30% at 4 years. This risk was higher in patients receiving chemotherapy (43% at 1 year and 49% at 4 years). Overall, patients with thrombocytopenia had higher 30-days rates of bleeding (HR = 1.72 [95% confidence interval, CI: 1.41-2.11]). Thrombocytopenia was also associated with an increased rate of transfusion, and death, but some of the risk estimates were imprecise.

CONCLUSIONS

The risk of thrombocytopenia was substantial among patients with solid tumors and associated with adverse outcomes.

Risk of cardiac conduction disorders, and pacemaker implantations among individuals tested for serum Borrelia burgdorferi antibodies, a nationwide, matched, population-based cohort study

OBJECTIVES

To investigate the short- and long-term risks of atrioventricular block and other cardiac conduction disorders associated with being tested for Borrelia burgdorferi (Bb) antibodies or Bb seropositivity as measures of confounding by indication and Bb infection, respectively.

METHODS

We performed a nationwide population-based matched cohort study (Denmark, 1993-2021). We included 52 200 Bb-seropositive individuals (stratified as only Bb-IgM-seropositive [n = 26 103], only Bb-IgG-seropositive [n = 18 698], and Bb-IgM-and-IgG-seropositive [n = 7399]) and two age- and sex-matched comparison cohorts: 104 400 Bb-seronegative individuals and 261 000 population controls. We investigated the risk associated with being tested for serum Bb antibodies and being Bb seropositive. Outcomes were atrioventricular block and other conduction disorders. We calculated short-term odds ratios (aOR) (within 1 month), and long-term hazard ratios (aHR) (after 1 month) adjusted for age, sex, diabetes, chronic heart failure, and kidney disease with 95% CI.

RESULTS

Compared with population controls, individuals tested for Bb antibodies had increased short- and long-term risks of atrioventricular block (aOR 47.9, 95% CI: 30.0-76.7, aHR 1.3, 95% CI:1.2-1.3), and other conduction disorders (aOR 18.2, 95% CI: 10.1-32.8, aHR 1.2, 95% CI: 1.1-1.4). Compared with Bb-seronegative individuals, only Bb-IgM-and-IgG-seropositive individuals had increased short-term risk of atrioventricular block (aOR: 2.1, 95% CI: 1.5-3.1).

DISCUSSION

The results suggest that Bb antibody testing is included in the diagnostic work-up of conduction disorders. Finally, that Bb seropositivity is not associated with other conduction disorders than atrioventricular block or with increased long-term risk of conduction disorders.

Describing diversity of real world data sources in pharmacoepidemiologic studies: The DIVERSE scoping review

PURPOSE

Real-world evidence (RWE) is increasingly used for medical regulatory decisions, yet concerns persist regarding its reproducibility and hence validity. This study addresses reproducibility challenges associated with diversity across real-world data sources (RWDS) repurposed for secondary use in pharmacoepidemiologic studies. Our aims were to identify, describe and characterize practices, recommendations and tools for collecting and reporting diversity across RWDSs, and explore how leveraging diversity could improve the quality of evidence.

METHODS

In a preliminary phase, keywords for a literature search and selection tool were designed using a set of documents considered to be key by the coauthors. Next, a systematic search was conducted up to December 2021. The resulting documents were screened based on titles and abstracts, then based on full texts using the selection tool. Selected documents were reviewed to extract information on topics related to collecting and reporting RWDS diversity. A content analysis of the topics identified explicit and latent themes.

RESULTS

Across the 91 selected documents, 12 topics were identified: 9 dimensions used to describe RWDS (organization accessing the data source, data originator, prompt, inclusion of population, content, data dictionary, time span, healthcare system and culture, and data quality), tools to summarize such dimensions, challenges, and opportunities arising from diversity. Thirty-six themes were identified within the dimensions. Opportunities arising from data diversity included multiple imputation and standardization.

CONCLUSIONS

The dimensions identified across a large number of publications lay the foundation for formal guidance on reporting diversity of data sources to facilitate interpretation and enhance replicability and validity of RWE.

The association of postoperative morbidity and age on 5-year survival after colorectal surgery in the elderly population: a nationwide cohort study

AIM

This study aimed to evaluate the association of age and postoperative morbidity on 5-year overall survival (OS) after elective surgery for colorectal cancer.

METHOD

Patients undergoing elective, curatively intended surgery for colorectal cancer Union for International Cancer Control Stages I-III between January 2014 and December 2019 were selected from four Danish nationwide healthcare databases. Patients were divided into four groups: group I 65-69 years old; group II 70-74 years old; group III 75-79 years old; and group IV ≥80 years old. Propensity score matching was used to reduce potential confounding bias. The primary outcome was the association of age and postoperative morbidity with 5-year OS. The secondary outcome was conditional survival, given that the patient had already survived the first 90 days after surgery.

RESULTS

After propensity score matching with a 1:1 ratio, group II contained 2221 patients; group III 952 patients; and group IV 320 patients. There was no significant difference in 5-year OS between group I (reference) and groups II and III (P = 0.4 and P = 0.9, respectively). Patients with severe postoperative complications within 30 days after surgery had a significantly decreased OS (P < 0.01); however, when patients who died within the first 90 days were excluded from the analysis, the differences in 5-year OS were less pronounced across all age groups.

CONCLUSION

Postoperative morbidity, and not patient age, was associated with a lower 5-year OS. Long-term survival for patients who experience a complication is similar to patients who did not have a complication when conditioning on 90 days of survival.

Neonatal outcomes in women with Multiple Sclerosis - Influence of disease activity: A Danish nationwide cohort study

BACKGROUND

Maternal Multiple Sclerosis (MS) has been associated with an increased risk of adverse birth outcomes. We hypothesized that active disease during conception and pregnancy plays an important role in this context, which this study aims to address.

METHODS

We used the Danish registers to conduct a nationwide cohort study. Information on maternal disease activity during pregnancy was retrieved using proxies from the linked registers (hospitalization, magnetic resonance imaging of the brain, and use of systemic corticosteroids during pregnancy). Neonates, exposed in utero to maternal disease activity constituted the exposed cohort and the unexposed cohort constituted neonates without in utero exposure to maternal disease activity. The examined outcomes were preterm birth, small for gestational age, low 5-minute Apgar score, and major congenital anomalies. In logistic regression models we estimated the odds ratios (OR) with adjustment for confounders such as maternal age, comorbidities, parity, smoking, calendar year of birth, and disease-modifying treatment.

RESULTS

Among the study population of 2492 children of mothers with MS we identified 273 (11 %) neonates exposed to maternal disease activity during pregnancy, and 2219 (89 %) neonates without exposure to disease activity. The adjusted odds ratios (aOR) for preterm birth, small for gestational age, low 5-minute Apgar score, and major congenital anomalies among children born to women with disease activity during pregnancy were 0.92 (95 % confidence interval (95 % CI) 0.53-1.60), aOR 1.19 (95 % CI 0.62-2.26), aOR 2.57 (95 % CI 0.93-7.15) and aOR 0.93 (95 % CI 0.48-1.83), respectively.

CONCLUSIONS

Women with MS having disease activity during pregnancy did not have a statistically significantly increased risk of adverse neonatal outcomes compared to women with MS without disease activity, which is overall reassuring results. We believe, that this will be useful knowledge for patients and clinicians in planning a pregnancy and preparing a birth plan.

Comparative epidemiology of bacteraemia in two ageing populations: Singapore and Denmark

Burden of bacteraemia is rising due to increased average life expectancy in developed countries. This study aimed to compare the epidemiology and outcomes of bacteraemia in two similarly ageing populations with different ethnicities in Singapore and Denmark. Historical cohorts from the second largest acute-care hospital in Singapore and in the hospitals of two Danish regions included patients aged 15 and above who were admitted from 1 January 2006 to 31 December 2016 with at least 1 day of hospital stay and a pathogenic organism identified. Among 13 144 and 39 073 bacteraemia patients from Singapore and Denmark, similar 30-day mortality rates (16.5%; 20.3%), length of hospital stay (median 14 (IQR: 9-28) days; 11 (6-21)), and admission rate to ICU (15.5%; 15.6%) were observed, respectively. Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus ranked among the top four in both countries. However, Singaporeans had a higher proportion of patients with diabetes (46.8%) and renal disease (29.5%) than the Danes (28.0% and 13.7%, respectively), whilst the Danes had a higher proportion of patients with chronic pulmonary disease (18.0%) and malignancy (35.3%) than Singaporeans (9.7% and 16.2%, respectively). Our study showed that top four causative organisms and clinical outcomes were similar between the two cohorts despite pre-existing comorbidities differed.

Semaglutide (Ozempic®) Use in Denmark 2018 Through 2023 ‒ User Trends and off-Label Prescribing for Weight Loss

Purpose

A surge in the use of semaglutide injection (Ozempic®) approved to treat type 2 diabetes (T2D) has led to a global supply shortage. We investigated contemporary user rates and clinical characteristics of semaglutide (Ozempic®) users in Denmark, and the extent of "off-label" prescribing for weight loss.

Patients and Methods

Nationwide population-based cross-sectional study based on linked health registries January 2018 through December 2023. All adults who received a first prescription of semaglutide once weekly (Ozempic®) were included. We examined quarterly rates of new users and total user prevalences, using other glucagon-like peptide-1 receptor agonists and weight loss medications as comparison. We also investigated user characteristics including T2D, glucose control, comedications, and cardiorenal disease.

Results

The new user rate of semaglutide (Ozempic®) remained stable at approximately 4 per 1000 adult person-years between 2019 and 2021 and then accelerated, peaking at 10 per 1000 in the first quarter of 2023 after which it declined sharply. User prevalence increased to 91,626 users in Denmark in 2023. The proportion of semaglutide (Ozempic®) new users who had a record of T2D declined from 99% in 2018 to only 67% in 2022, increasing again to 87% in 2023. Among people with T2D who initiated semaglutide (Ozempic®) in 2023, 52% received antidiabetic polytherapy before initiation, 39% monotherapy, and 8% no antidiabetic therapy. Most T2D initiators had suboptimal glucose control, with 83% having an HbA1c ≥48 mmol/mol and 68% ≥53 mmol/mol despite use of antidiabetic medication, and 29% had established atherosclerotic cardiovascular disease or kidney disease.

Conclusion

The use of semaglutide (Ozempic®) in Denmark has increased dramatically. Although not approved for weight loss without T2D, one-third of new users in 2022 did not have T2D. Conversely, most initiators with T2D had a clear medical indication for treatment intensification, and "off-label" use can only explain a minor part of the supply shortage.

Social characteristics and social benefit use among premenopausal breast cancer survivors in Denmark: a population-based cohort study

PURPOSE

In 2020, one million women aged < 55 years were diagnosed with breast cancer globally. The impact of breast cancer and its treatments on these women's ability to work and need for social benefits may differ by social characteristics. We evaluated social benefit use following breast cancer by education and cohabitation.

METHODS

We conducted a nationwide population-based cohort study, including women aged 18-55 years diagnosed with stage I-III breast cancer in Denmark during 2002-2011. Statistics Denmark provided information on cohabitation, education, and social benefit use from 1 year pre-diagnosis to 10 years post-diagnosis. We calculated weekly proportions of self-support, unemployment, disability pension, flexi jobs, and sick leave according to education and cohabitation.

RESULTS

Of 5345 women, 81.8% were self-supporting, 4.5% received disability pensions, 1.6% had flexi jobs, 3.6% were on sick leave, and 5.5% were unemployed 1 year pre-diagnosis. Ten years post-diagnosis, the proportions were 69.0%, 13.0%, 10.5%, 3.4%, and 2.0% of 3663 survivors. Disability pensions and flexi jobs increased from 12.1 to 26.4% and 2.8 to 13.5% in women with short education, from 4.1 to 12.8% and 1.8 to 12.2% in women with medium education, and from 0.8 to 6.0% and 0.9 to 6.9% in longer educated. Disability pensions increased more in women living alone (7.8 to 19.9%), than in cohabiting women (3.6 to 11.3%).

CONCLUSIONS

Use of social benefits reflecting lost ability to work was highest in less educated women and in women living alone.

IMPLICATIONS FOR CANCER SURVIVORS

Awareness of these groups is crucial when tailoring efforts to support work participation in cancer survivors.

Increased cancer incidence among patients with hidradenitis suppurativa - a Danish nationwide register study 1977-2017

BACKGROUND

The chronic, inflammatory skin disease hidradenitis suppurativa (HS) (prevalence: 0.5%-1%, diagnostic delay: 7-10 years) primarily arises in younger adults and frequently coincides with autoimmune comorbidities and unhealthy life-styles (smoking and obesity). These factors are known to increase cancer risk, but despite this, information on cancer occurrence among HS patients is scarce.

MATERIALS AND METHODS

A nationwide retrospective register-based study assessing relative risk of cancer - overall and by anatomical site - following HS diagnosis expressed as standardized incidence ratios (SIRs), which is ratios between observed cases among all Danes diagnosed with HS since 1977 and expected cases based on cancer incidence rates of the entire Danish population during the same period.

RESULTS

Participants consisted of a cohort of 13,919 Danes with HS, who during an average of 14.2 years of follow-up developed a total of 1,193 incident cancers, corresponding to a 40% increased risk (SIR = 1.4, 95% CI: 1.3 to 1.4, p < 0.001). Increased risks were observed for cancers of the respiratory system, oral cavity and pharynx, digestive organs and peritoneum, urinary tract, and the lymphatic tissues.

INTERPRETATION

These findings underline an unmet need for health monitoring, lifestyle interventions and cancer screening if and when relevant.

Acute patients discharged without an established diagnosis: risk of mortality and readmission of nonspecific diagnoses compared to disease-specific diagnoses

BACKGROUND

Nonspecific discharge diagnoses after acute hospital courses represent patients discharged without an established cause of their complaints. These patients should have a low risk of adverse outcomes as serious conditions should have been ruled out. We aimed to investigate the mortality and readmissions following nonspecific discharge diagnoses compared to disease-specific diagnoses and assessed different nonspecific subgroups.

METHODS

Register-based cohort study including hospital courses beginning in emergency departments across 3 regions of Denmark during March 2019-February 2020. We identified nonspecific diagnoses from the R- and Z03-chapter in the ICD-10 classification and excluded injuries, among others-remaining diagnoses were considered disease-specific. Outcomes were 30-day mortality and readmission, the groups were compared by Cox regression hazard ratios (HR), unadjusted and adjusted for socioeconomics, comorbidity, administrative information and laboratory results. We stratified into short (3-<12 h) or lengthier (12-168 h) hospital courses.

RESULTS

We included 192,185 hospital courses where nonspecific discharge diagnoses accounted for 50.7% of short and 25.9% of lengthier discharges. The cumulative risk of mortality for nonspecific vs. disease-specific discharge diagnoses was 0.6% (0.6-0.7%) vs. 0.8% (0.7-0.9%) after short and 1.6% (1.5-1.7%) vs. 2.6% (2.5-2.7%) after lengthier courses with adjusted HRs of 0.97 (0.83-1.13) and 0.94 (0.85-1.05), respectively. The cumulative risk of readmission for nonspecific vs. disease-specific discharge diagnoses was 7.3% (7.1-7.5%) vs. 8.4% (8.2-8.6%) after short and 11.1% (10.8-11.5%) vs. 13.7% (13.4-13.9%) after lengthier courses with adjusted HRs of 0.94 (0.90-0.98) and 0.95 (0.91-0.99), respectively. We identified 50 clinical subgroups of nonspecific diagnoses, of which Abdominal pain (n = 12,462; 17.1%) and Chest pain (n = 9,599; 13.1%) were the most frequent. The subgroups described differences in characteristics with mean age 41.9 to 80.8 years and mean length of stay 7.1 to 59.5 h, and outcomes with < 0.2-8.1% risk of 30-day mortality and 3.5-22.6% risk of 30-day readmission.

CONCLUSIONS

In unadjusted analyses, nonspecific diagnoses had a lower risk of mortality and readmission than disease-specific diagnoses but had a similar risk after adjustments. We identified 509 clinical subgroups of nonspecific diagnoses with vastly different characteristics and prognosis.

Employment Status Following Heart Transplantation: Data From the Danish Nationwide Social Service Payment Register During 20 years

Most studies on vocational rehabilitation after heart transplantation (HTX) are based on self-reported data. Danish registries include weekly longitudinal information on all public transfer payments. We intended to describe 20-year trends in employment status for the Danish heart-transplant recipients, and examine the influence of multimorbidity and socioeconomic position (SEP). Linking registry and Scandiatransplant data (1994-2018), we conducted a study in recipients of working age (19-63 years). The cohort contained 492 recipients (79% males) and the median (IQR) age was 52 years (43-57 years). Five years after HTX, 30% of the survived recipients participated on the labor market; 9% were in a flexible job with reduced health-related working capacity. Moreover, 60% were retired and 10% eligible for labor market participation were unemployed. Recipients with multimorbidity had a higher age and a lower prevalence of employment. Five years after HTX, characteristics of recipients with labor market participation were: living alone (27%) versus cohabitation (73%); low (36%) versus medium-high (64%) educational level; low (13%) or medium-high (87%) income group. Heart-transplant recipients with multimorbidity have a higher age and a lower prevalence of employment. Socioeconomically disadvantaged recipients had a lower prevalence of labor market participation, despite being younger compared with the socioeconomically advantaged.

Predictors and long-term patterns of medication adherence to glaucoma treatment in Denmark-an observational registry study of 30 100 Danish patients with glaucoma

BACKGROUND

Self-treatment with glaucoma medication (eye drops) has been associated with adherence challenges. Poor adherence results in worse outcomes in terms of visual field loss.

OBJECTIVE

To investigate patterns in medication adherence among Danish patients with glaucoma in relation to selected predictors of adherence, long-term adherence patterns, and long-term societal economic consequences of poor adherence.

METHODS AND ANALYSIS

This register-based study included 30 100 glaucoma patients followed for 10 years between 2000 and 2018. Glaucoma was identified from the Danish national registers by diagnosis of Open Angle Glaucoma and/or by redeemed prescriptions of glaucoma medication. Logistic regression models were applied to estimate patient characteristics related to medical adherence. Diagnosis-related group fees were applied to estimate healthcare costs.

RESULTS

High adherence in the first year(s) of treatment was less likely among men (ORfirst year: 0.78, 95% CI: 0.75 to 0.82), younger individuals and among those with a positive Charlson Comorbidity Index (CCI) score (ORfirst year/CCI≥3: 0.71, 95% CI: 0.63 to 0.80). Adherence in the first year and in the first two years was associated with adherence in the fifth (ORfirst year: 4.55, 95% CI: 4.30 to 4.82/ORfirst two years: 6.47, 95% CI: 6.10 to 6.86) as with adherence in the 10th year with slightly lower estimates. Being medical adherent was related to higher costs related to glaucoma medication after 5 and 10 years comparing with poor adherence, whereas poor adherence was associated with a marked increase in long-term costs for hospital contacts.

CONCLUSION

Increasing age, female sex and low comorbidity score are correlated with better adherence to glaucoma treatment. Adherence in the first years of treatment may be a good predictor for future adherence. In the long term, patients with poor adherence are overall more expensive to society in terms of hospital contacts.

Predicting the risks of kidney failure and death in adults with moderate to severe chronic kidney disease: multinational, longitudinal, population based, cohort study

OBJECTIVE

To train and test a super learner strategy for risk prediction of kidney failure and mortality in people with incident moderate to severe chronic kidney disease (stage G3b to G4).

DESIGN

Multinational, longitudinal, population based, cohort study.

SETTINGS

Linked population health data from Canada (training and temporal testing), and Denmark and Scotland (geographical testing).

PARTICIPANTS

People with newly recorded chronic kidney disease at stage G3b-G4, estimated glomerular filtration rate (eGFR) 15-44 mL/min/1.73 m2.

MODELLING

The super learner algorithm selected the best performing regression models or machine learning algorithms (learners) based on their ability to predict kidney failure and mortality with minimised cross-validated prediction error (Brier score, the lower the better). Prespecified learners included age, sex, eGFR, albuminuria, with or without diabetes, and cardiovascular disease. The index of prediction accuracy, a measure of calibration and discrimination calculated from the Brier score (the higher the better) was used to compare KDpredict with the benchmark, kidney failure risk equation, which does not account for the competing risk of death, and to evaluate the performance of KDpredict mortality models.

RESULTS

67 942 Canadians, 17 528 Danish, and 7740 Scottish residents with chronic kidney disease at stage G3b to G4 were included (median age 77-80 years; median eGFR 39 mL/min/1.73 m2). Median follow-up times were five to six years in all cohorts. Rates were 0.8-1.1 per 100 person years for kidney failure and 10-12 per 100 person years for death. KDpredict was more accurate than kidney failure risk equation in prediction of kidney failure risk: five year index of prediction accuracy 27.8% (95% confidence interval 25.2% to 30.6%) versus 18.1% (15.7% to 20.4%) in Denmark and 30.5% (27.8% to 33.5%) versus 14.2% (12.0% to 16.5%) in Scotland. Predictions from kidney failure risk equation and KDpredict differed substantially, potentially leading to diverging treatment decisions. An 80-year-old man with an eGFR of 30 mL/min/1.73 m2 and an albumin-to-creatinine ratio of 100 mg/g (11 mg/mmol) would receive a five year kidney failure risk prediction of 10% from kidney failure risk equation (above the current nephrology referral threshold of 5%). The same man would receive five year risk predictions of 2% for kidney failure and 57% for mortality from KDpredict. Individual risk predictions from KDpredict with four or six variables were accurate for both outcomes. The KDpredict models retrained using older data provided accurate predictions when tested in temporally distinct, more recent data.

CONCLUSIONS

KDpredict could be incorporated into electronic medical records or accessed online to accurately predict the risks of kidney failure and death in people with moderate to severe CKD. The KDpredict learning strategy is designed to be adapted to local needs and regularly revised over time to account for changes in the underlying health system and care processes.

Validity of Prescription-Defined and Hospital-Diagnosed Hypertension Compared with Self-Reported Hypertension in Denmark

Purpose

Hypertension is an important risk factor in cardio-epidemiological research, but data quality remains a concern. We validated different registry-based definitions of hypertension.

Patients and Methods

The cohort included all first-time responders of the Danish National Health Surveys (2010, 2013, or 2017). Prescription-defined hypertension was defined as ≥1 or ≥2 filled prescriptions of antihypertensive specific drugs in ≥1 or ≥2 different antihypertensive drug classes within 90, 180, or 365 days before survey response. Hospital-diagnosed hypertension was defined from hypertension diagnoses within five years before the survey response. Considering self-reported hypertension as the reference, we calculated the positive predictive value (PPV), the negative predictive value (NVP), the sensitivity, and the specificity of prescription-defined and hospital-diagnosed hypertension.

Results

Among 442,490 survey responders, 127,247 (29%) had self-reported hypertension. For prescription-defined hypertension with 365-day lookback, the PPV was highest for ≥2 prescriptions in ≥2 drug classes (94%) and lowest for ≥1 prescription in ≥1 drug class (85%). The NPV was highest for ≥1 prescription in ≥2 drug classes (94%) and lowest for ≥1 prescription in ≥2 drug classes (80%). The sensitivity was highest for ≥1 prescription in ≥1 drug class (79%) and lowest for ≥2 prescriptions in ≥2 drug classes (30%). The specificity was ≥94% for all algorithms. The PPV and specificity did not change noteworthy with length of lookback period, whereas the NPV and the sensitivity generally were higher for longer lookback. The algorithm ≥1 prescription in ≥2 drug classes with 365-day lookback was among the best balanced across all measures of validity (PPV=88%, NPV=94%, sensitivity=75%, specificity=96%). For hospital-diagnosed hypertension, the PPV was 90%, the NPV was 76%, the sensitivity was 22%, and the specificity was 99%.

Conclusion

Compared with self-reported hypertension, the algorithms for prescription-defined and hospital-diagnosed hypertension had high predictive values and specificity, but low sensitivity.

Excessive androgen exposure and risk of malignancies: A cohort study

BACKGROUND

A link between androgen use and the risk of cancers, especially prostate and breast cancer, has been suggested. The knowledge about a possible association is limited.

OBJECTIVE

The study aimed to investigate cancer incidence rates, particularly those related to prostate and breast cancer, in male androgen users and compare them to a control group.

METHODS

We included male androgen users identified through a nationwide anti-doping testing program in Danish fitness centers from 2006 to 2018. We paired each case with 50 male controls of the same age, selected randomly. The cohort was followed from baseline and until 2023. The outcome was the incidence of prostate cancer, breast cancer, or any cancer excluding non-melanoma skin cancer.

RESULTS

The study included 1,189 androgen users and 59,450 controls, with a mean age of 27 years at enrolment. During the follow-up period with a mean length of 11 years, 13 androgen users, and 612 controls were diagnosed with cancer. This resulted in an incidence rate ratio of 1.05 (95% CI: 0.55-1.81). None of the androgen users were diagnosed with prostate or breast cancer.

DISCUSSION AND CONCLUSION

Male androgen users did not face an increased short-term risk of cancer, neither overall nor related to prostate or breast cancer. Our study indicates that the absolute risk of malignancies in androgen users is comparable to that in the background population. However, we cannot exclude androgens as a cancer risk factor due to the limited sample size, relatively short follow-up period, and subject age.

Mortality Among Users of Anabolic Steroids

This cohort study investigates mortality and cause of death among a large cohort of androgenic anabolic steroid users, compared with a control group, in Denmark from January 3, 2006, to March 1, 2018.

Clinical factors associated with patterns of endocrine therapy adherence in premenopausal breast cancer patients

INTRODUCTION

Patients with hormone receptor positive breast cancer are recommended at least five years of adjuvant endocrine therapy, but adherence to this treatment is often suboptimal. We investigated longitudinal trends in adjuvant endocrine therapy (AET) adherence among premenopausal breast cancer patients and identified clinical characteristics, including baseline comorbidities and non-cancer chronic medication use, associated with AET adherence.

METHODS

We included stage I-III premenopausal breast cancer patients diagnosed during 2002-2011 and registered in the Danish Breast Cancer Group clinical database who initiated AET. We used group-based trajectory modeling to describe AET adherence patterns. We also linked patients to Danish population-based registries and fit multinomial logistic models to compute odds ratios (ORs) and 95% confidence intervals (95% CIs) associating clinical characteristics with AET adherence patterns.

RESULTS

We identified three adherence patterns among 4,353 women-high adherers (57%), slow decliners (36%), and rapid decliners (6.9%). Women with stage I disease (vs. stage II; OR: 1.9, 95% CI 1.5, 2.5), without chemotherapy (vs. chemotherapy; OR: 4.3, 95% CI 3.0, 6.1), with prevalent comorbid disease (Charlson Comorbidity Index score ≥ 1 vs. 0; OR: 1.6, 95% CI 1.1, 2.3), and with a history of chronic non-cancer medication use (vs. none; OR: 1.3, 95% CI 1.0, 1.8) were more likely to be rapid decliners compared with high adherers.

CONCLUSIONS

Women with stage I cancer, no chemotherapy, higher comorbidity burden, and history of chronic non-cancer medication use were less likely to adhere to AET. Taking steps to promote adherence in these groups of women may reduce their risk of recurrence.

Retrospective and prospective study designs

The labels "retrospective" and "prospective" strongly connote study quality, often favouring prospective studies. However, three definitions of these terms exist, each suggesting distinct methodological limitations. In this review, we summarize and evaluate these definitions. Caution is warranted when labeling a study "retrospective": This label should only be used when implying a risk of recall bias, which can only occur in retrospective data collection. Generally, assessing random and systematic errors is necessary to appraise study quality rather than relying on ambiguous labels.

Time trends in opioid use for patients undergoing hip fracture surgery in 1997-2018: A Danish population-based cohort study

BACKGROUND

Although opioids are a mainstay for perioperative pain management in hip fracture patients, no studies have described changes in opioid use over the last two decades. The aim of this study was to describe time trends in opioid use in a population-based cohort of patients undergoing a first-time hip fracture surgery during 1997-2018.

METHODS

Opioid-naïve hip fracture patients >55 years old were identified in Danish medical databases (n = 115,962). By 2-year calendar periods, we calculated prevalence rates (PR) of opioid use in the four quarters after surgery (Q1-Q4). Corresponding prevalence rate ratios (PRR) with 1997-1998 as a reference were estimated with 95% confidence intervals. Further, we calculated the median morphine milligram equivalents (MME) for each quarter.

RESULTS

For Q1, the PR of opioid use increased from 29% in 1997-1998 to 78% in 2017-2018 corresponding to a PRR of 2.7 (2.6-2.8). For Q4, the PR was 15% in 1997-1998, peaked in 2003-2004 and then decreased, but stayed high at 13% in 2017-2018. The median MME did not increase when comparing 2017-2018 with 1997-1998, irrespective of the quarter. Tramadol was most frequently used in 1997-1998 shifting to oxycodone in 2017-2018.

CONCLUSION

The PRs of opioid use in Q1 after surgery increased substantially from 1997 to 2018, but this did not translate into increased opioid use up to 1 year after hip fracture surgery or higher dosage. Our findings underline the importance of sustained focus on opioid tapering, dosage and use of opioids with the lowest potential for addiction and other adverse events.

SIGNIFICANCE STATEMENT

Overall, opioid use in Q1 after hip fracture surgery increased 2.7 times from 1997 to 2018, but the doses and opioid use up to 1 year after surgery remained stable. Compared to elderly, younger patients were more likely to use opioid in Q1, while the tendency was opposite in Q2-Q4. The most used opioid type changed from tramadol to oxycodone. Our findings underline the importance of personalized opioid tapering and doses, and use of opioids with the lowest potential for addiction and other adverse events.

Long-term aspirin use and cancer risk: a 20-year cohort study

BACKGROUND

Long-term use of aspirin has been shown to reduce colorectal cancer risk, but the association remains inconclusive for individual noncolorectal cancers. We examined the association between long-term aspirin use and cancer risk in Denmark.

METHODS

Using nationwide registries, we followed individuals aged 40-70 years at baseline (January 1, 1997) for cancer diagnoses through 2018. We assessed low-dose (75-150 mg) aspirin use according to continuity, duration, and cumulative amount. In addition, we explored associations with consistent high-dose (500 mg) aspirin use. Using Cox regression, we estimated multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) with aspirin use for overall and site-specific cancer.

RESULTS

Among 1 909 531 individuals, 422 778 were diagnosed with cancer during mean follow-up of 18.2 years. Low-dose aspirin use did not reduce the hazard ratio for cancer overall irrespective of continuity and duration of use (continuous use: HR = 1.04, 95% CI = 1.03 to 1.06). However, long-term (≥5 or ≥10 years) use was associated with at least 10% reductions in hazard ratios for several cancer sites: colon, rectum, esophagus, stomach, liver, pancreas, small intestine, head and neck, brain tumors, meningioma, melanoma, thyroid, non-Hodgkin lymphoma, and leukemia. Substantially elevated hazard ratios were found for lung and bladder cancer. In secondary analyses, consistent high-dose aspirin use was associated with reduced hazard ratios for cancer overall (HR = 0.89, 95% CI = 0.85 to 0.93) and for several cancer sites.

CONCLUSION

Long-term low-dose aspirin use was associated with slight to moderately reduced risks for several cancers but not for cancer overall owing to increased risk for some common cancers. Similar or slightly stronger inverse associations were observed for consistent use of high-dose aspirin.

Risk of cardiovascular disease after hospital-diagnosed overweight or obesity

Objective

The aim was to examine the association between hospital-diagnosed overweight/obesity and incident CVD according to the time period of the overweight/obesity diagnosis.

Design

This is a cohort study.

Methods

From Danish national health registries, we identified all residents with a first-time hospital-based overweight/obesity diagnosis code, 1977-2018 (n = 195,221), and an age and sex-matched general population comparison cohort (n = 1,952,210). We computed adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) using Cox regression. We adjusted for comorbidities and educational level and applied 10 years of follow-up.

Results

The overall incidence rate was 10.1 (95% CI 10.0-10.1) per 1000 person-years for the comparison cohort and 25.1 (95% CI 24.8-25.4) per 1000 person-years for the overweight/obesity cohort, corresponding to an aHR of 2.5 (95% CI 2.4-2.5). The aHR was elevated for all subtypes of CVD: heart failure: 3.9 (95% CI 3.7-4.1), bradyarrhythmia: 2.9 (95% CI 2.7-3.1), angina pectoris: 2.7 (95% CI 2.7-2.8), atrial fibrillation or flutter: 2.6 (95% CI 2.5-2.6), acute myocardial infarction: 2.4 (95% CI 2.3-2.4), revascularization procedure: 2.4 (95% CI 2.2-2.5), valvular heart disease: 1.7 (95% CI 1.6-1.8), ischemic stroke: 1.6 (95% CI 1.4-1.7), transient ischemic attack: 1.6 (95% CI 1.5-1.7), and cardiovascular death: 1.6 (95% CI 1.5-1.6). The 1-10-year aHR of any CVD associated with an overweight/obesity diagnosis decreased from 2.8 (95% CI 2.7-2.9) in 1977-1987 to 1.8 (95% CI 1.8-1.9) in 2008-2018.

Conclusion

Patients with hospital-diagnosed overweight/obesity had high rates of ischemic heart disease, heart failure, structural heart disease, arrhythmia, stroke, and death, although the strength of the association decreased in recent years.

Significance statement

Obesity is linked to metabolic abnormalities that predispose individuals to an increased risk of subtypes of CVD. In this population-based nationwide 40-year cohort study, we found that of 195,221 patients with an overweight/obesity diagnosis, more than 31,000 (15.9%) were admitted to hospital within 10 years because of CVD; corresponding to a 2.5-fold greater relative risk of any CVD associated with overweight/obesity than in the general population. We observed an increased risk for most CVD subtypes, including ischemic heart disease, heart failure, structural heart disease, arrhythmia, stroke, and cardiovascular death, although the strength of the association decreased in recent years. Our study emphasizes the importance of improved clinical handling of obesity and underscores the need to prevent associated complications to alleviate the burden of obesity.

Opportunistically identifiable vertebral fractures on routine radiological imaging predict mortality: observational cohort study

In men and women with opportunistically identifiable vertebral fractures (VFs) on routine CT scans including the chest and/or abdomen, the risk of death is 51% higher than in those with no VF on the CT scan, and 325% higher than an age- and sex-matched general population cohort.

PURPOSE

There is little knowledge about the risk of death in patients with VFs present on routine radiological imaging. We evaluated the risk of death in men and women aged 50 years or older with opportunistically identifiable VFs on routine CT scans and not treated with osteoporosis medications.

METHODS

Thoracic and lumbar VFs were identified through a blinded, two-step approach on CT scans performed as part of normal clinical care in a Danish hospital in 2010 or later. Subjects with VF were matched on age and sex against those with no VF (1:2-ratio) and a general population cohort (1:3-ratio), respectively, and followed for up to 7 years through the national Danish registers. Subjects treated with an osteoporosis medication in the year prior to baseline were excluded.

RESULTS

Subjects with VF had a significantly higher risk of death during follow-up as compared to subjects with no VF on the CT scan (adjusted hazard ratio [HR] 1.51 [95% confidence interval 1.27-1.79; p < 0.001]) and even more so when compared to the general population cohort (HR 4.25 [3.53-5.12; p < 0.001]). In subjects with versus without VF on the CT scan, the risk was higher in those with moderate or severe VF, in those with no malignancy prior to baseline, and in those with a lower Charlson comorbidity index score.

CONCLUSION

Subjects with VF available for identification on routine CT scans face a substantially increased risk of death. Opportunistic identification and reporting of VF is important to identify these patients to allow intervention if indicated.

Association between mortality and phone-line waiting time for non-urgent medical care: a Danish registry-based cohort study

BACKGROUND AND IMPORTANCE

Telephone calls are often patients' first healthcare service contact, outcomes associated with waiting times are unknown.

OBJECTIVES

Examine the association between waiting time to answer for a medical helpline and 1- and 30-day mortality.

DESIGN, SETTING AND PARTICIPANTS

Registry-based cohort study using phone calls data (January 2014 to December 2018) to the Capital Region of Denmark's medical helpline. The service refers to hospital assessment/treatment, dispatches ambulances, or suggests self-care guidance.

EXPOSURE

Waiting time was grouped into the following time intervals in accordance with political service targets for waiting time in the Capital Region: <30 s, 0:30-2:59, 3-9:59, and ≥10 min.

OUTCOME MEASURES AND ANALYSIS

The association between time intervals and 1- and 30-day mortality per call was calculated using logistic regression with strata defined by age and sex.

MAIN RESULTS

In total, 1 244 252 callers were included, phoning 3 956 243 times, and 78% of calls waited <10 min. Among callers, 30-day mortality was 1% (16 560 deaths). For calls by females aged 85-110 30-day mortality increased with longer waiting time, particularly within the first minute: 9.6% for waiting time <30 s, 10.8% between 30 s and 1 minute and 9.1% between 1 and 2 minutes. For calls by males aged 85-110 30-day mortality was 11.1%, 12.9% and 11.1%, respectively. Additionally, among calls with a Charlson score of 2 or higher, longer waiting times were likewise associated with increased mortality. For calls by females aged 85-110 30-day mortality was 11.6% for waiting time <30 s, 12.9% between 30 s and 1 minute and 11.2% between 1 and 2 minutes. For calls by males aged 85-110 30-day mortality was 12.7%, 14.1% and 12.6%, respectively. Fewer ambulances were dispatched with longer waiting times (4%/2%) with waiting times <30 s and >10 min.

CONCLUSION

Longer waiting times for telephone contact to a medical helpline were associated with increased 1- and 30-day mortality within the first minute, especially among elderly or more comorbid callers.

Older adults' perceptions of navigating eye health care in Denmark: a qualitative study

BACKGROUND

Vision impairment can have an impact on cognition, health, and social function. Vision loss may be avoided if detected early and treated promptly. Eye health is a minor topic in general practice, but the ongoing relationship between doctor and patient has the potential to assist the patient in navigating the healthcare system and guaranteeing timely healthcare service delivery.

AIM

To explore the attitudes of older members of the public (aged ≥60 years) towards navigating primary sector eye health care in Denmark, with a focus on optometrists, practising ophthalmologists (POs), and GPs.

DESIGN & SETTING

Qualitative study in Copenhagen, Denmark.

METHOD

Focus group interviews were performed in the spring of 2022 with 21 older members of the public.

RESULTS

Older members of the public perceived optometrists and POs to be the most relevant health professionals to consult about eye health. Opportunities were identified for enhancing the function of general practice including detecting early signs of visual impairment, being in charge of further referrals, and managing issues affecting quality of life such as dry eyes.

CONCLUSION

Older members of the public sought help from health professionals who are directly qualified to treat symptoms of vision impairment that patients are experiencing or expect to face in the near future. Participants identified a potential for GPs to address vision impairment. This included focusing on the patient's general health and function, as well as potential comorbidities influencing treatment trajectories. The current denigration of general practice risks missing out on the potential benefits of robust engagement from general practice in eye health.

Acute Kidney Injury Duration and 20-Year Risks of CKD and Cardiovascular Disease

Introduction

Acute kidney injury (AKI) is associated with chronic kidney disease (CKD) and cardiovascular disease (CVD); however, it is unclear whether AKI duration affects the long-term risks of CKD and CVD. Therefore, we performed a population-based cohort study examining the associations between AKI duration and CKD and CVD.

Methods

We identified patients with laboratory-recorded AKI in Denmark from 1990 through 2018. AKIs were categorized as rapid reversal AKI (≤48 hours), persistent AKI (2-7 days), and acute kidney disease (AKD) (>7 days). We estimated 20-year risks and adjusted hazard ratios (aHRs) of incident CKD and CVD.

Results

The study comprised 169,582 patients with AKI, with 100,478 and 76,838 included in the analysis of CKD and CVD, respectively. The 20-year risks of CKD were 26.3%, 29.5%, and 28.7% for rapid reversal AKI, persistent AKI, and AKD, respectively. Compared with rapid reversal AKI, aHRs were 1.13 (95% confidence interval [CI], 1.08-1.19) for persistent AKI and 1.36 (95% CI, 1.30-1.41) for AKD. Risks and rates of overall CVD were similar for rapid reversal AKI, persistent AKI, and AKD. However, persistent AKI was associated with a slightly increased aHR of heart failure (1.09; 95% CI, 1.02-1.16), and aHRs of heart failure, ischemic heart disease, and peripheral artery disease were slightly increased for AKD (1.09 [95% CI, 1.03-1.15], 1.11 [95% CI, 1.03-1.19], and 1.10 [95% CI, 1.02-1.17], respectively).

Conclusion

AKI duration was associated with development of CKD, but not overall CVD; however, rates of heart failure, ischemic heart disease, and peripheral artery disease increased slightly with AKI duration.

Proton pump inhibitors and the risk of acute kidney injury in cancer patients receiving immune checkpoint inhibitors: A Danish population-based cohort study

Previous studies have suggested that the use of proton pump inhibitors (PPIs) more than doubles the risk of acute kidney injury (AKI) in cancer patients receiving immune checkpoint inhibitors (ICIs). However, this association may be confounded. Therefore, we conducted a register-based cohort study to examine the risk of AKI in users and nonusers of PPIs among cancer patients treated with ICIs in Denmark from 2011 through 2021 while accounting for a comprehensive range of potential confounders. PPI use was determined based on redeemed prescriptions of PPIs before ICI initiation. We identified laboratory-recorded AKI events within the first year after ICI initiation. We estimated the risks and hazard ratios (HRs) of AKI while accounting for a comprehensive range of confounders (including comorbidities and comedication) by propensity score weighting. Furthermore, we performed an additional per-protocol analysis while accounting for informative censoring by weighting. We identified 10 200 cancer patients including 2749 (27%) users, 6214 (61%) nonusers, and 1237 (12%) former users of PPIs. PPI users had an increased risk of AKI compared to nonusers (1-year risk, 24.7% vs 19.9%; HR, 1.42 [95% confidence interval (CI), 1.29-1.56]); however, this association attenuated when accounting for confounders (weighted 1-year risk, 24.2% vs 23.8%; weighted HR, 1.06 [95% CI, 0.93-1.21]). In the per-protocol analysis, the crude HR was 1.86 (95% CI, 1.63-2.12), while the weighted HR was 1.24 (95% CI, 1.03-1.49). Thus, the association between PPI use and AKI could largely be explained by confounding, suggesting that previous studies may have overestimated the association.

The Effect of Coordinating the Outpatient Treatment across Medical Specialities for Patients With Multimorbidity

Introduction

Patients with multimorbidity attend multiple outpatient clinics. We assessed the effects on hospital use of scheduling several outpatient appointments to same-day visits in a multidisciplinary outpatient pathway (MOP).

Methods

This study used a quasi-experimental design. Eligible patients had multimorbidity, were aged ≥18 years and attended ≥2 outpatient clinics in five different specialties. Patients were identified through forthcoming appointments from August 2018 to March 2020 and divided into intervention group (alignment of appointments) and comparison group (no alignment). We used patient questionnaires and paired analyses to study care integration and treatment burden. Using negative binomial regression, we estimated healthcare utilisation as incidence rates ratios (IRRs) at one year before and one year after baseline for both groups and compared IRR ratios (IRRRs).

Results

Intervention patients had a 19% reduction in hospital visits (IRRR: 0.81, 95% CI: 0.70-0.96) and a 17% reduction in blood samples (IRRR: 0.83, 0.73-0.96) compared to comparison patients. No effects were found for care integration, treatment burden, outpatient contacts, terminated outpatient trajectories, hospital admissions, days of admission or GP contacts.

Conclusion

The MOP seemed to reduce the number of hospital visits and blood samples. These results should be further investigated in studies exploring the coordination of outpatient care for multimorbidity.

Research question

Can an intervention of coordinating outpatient appointments to same-day visits combined with a multidisciplinary conference influence the utilisation of healthcare services and the patient-assessed integration of healthcare services and treatment burden among patients with multimorbidity?

Large-Scale Neuroimaging of Mental Illness

Neuroimaging has provided important insights into the brain variations related to mental illness. Inconsistencies in prior studies, however, call for methods that lead to more replicable and generalizable brain markers that can reliably predict illness severity, treatment course, and prognosis. A paradigm shift is underway with large-scale international research teams actively pooling data and resources to drive consensus findings and test emerging methods aimed at achieving the goals of precision psychiatry. In parallel with large-scale psychiatric genomics studies, international consortia combining neuroimaging data are mapping the transdiagnostic brain signatures of mental illness on an unprecedented scale. This chapter discusses the major challenges, recent findings, and a roadmap for developing better neuroimaging-based tools and markers for mental illness.

Loneliness and the risk of type 2 diabetes

INTRODUCTION

The incidence of type 2 diabetes is increasing globally. Recent research suggests that loneliness could be a potential risk factor for the development of type 2 diabetes. We aimed to investigate the association between loneliness and type 2 diabetes and the modifying effect of mental disorders.

RESEARCH DESIGN AND METHODS

We conducted a prospective study including 465 290 adults (aged ≥16 years) who participated in either the Danish Health and Morbidity Survey or the Danish National Health Survey between 2000 and 2017. Loneliness was based on self-report, while type 2 diabetes was measured using an algorithm combining several health registers including type 2 diabetes patients treated both within the hospital sector and general practice. Cox proportional hazards regressions were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs).

RESULTS

During a mean follow-up time of 6.3 years, 13 771 individuals (3%) developed type 2 diabetes. Feeling lonely once in a while was associated with a 14% increased risk of type 2 diabetes (95% CI 1.09 to 1.20), while feeling lonely often was associated with a 24% increased risk (95% CI 1.14 to 1.34), independent of sociodemographic factors and body mass index. The association was stronger among individuals without a mental disorder (HR 1.21, 95% CI 1.10 to 1.34 among those feeling lonely often) compared with those with a mental disorder (HR 1.07, 95% CI 0.93 to 1.23).

CONCLUSIONS

Loneliness independently increased the risk of type 2 diabetes. The effect was more pronounced in individuals without a mental disorder, as having a mental disorder itself likely increases the risk of type 2 diabetes. These findings emphasize the importance of addressing loneliness as a modifiable risk factor in preventing type 2 diabetes.

Association between maternal employment status and presence of children with major congenital anomalies in Denmark

IMPORTANCE

The burden of caring for children with complex medical problems such as major congenital anomalies falls principally on mothers, who in turn suffer a variety of potentially severe economic consequences. As well, health consequences of caregiving often further impact the social and economic prospects of mothers of children with major congenital anomalies (MCMCAs). Evaluating the long-term economic consequences of extensive in-home caregiving among MCMCAs can inform strategies to mitigate these effects.

OBJECTIVE

To assess whether MCMCAs face reduced employment and increased need for disability benefits over a 20-year period.

DESIGN

A population-based matched cohort study.

SETTING

Denmark.

PARTICIPANTS

All women who gave birth to a singleton child with a major congenital anomaly in Denmark between January 1, 1997 and December 31, 2017 (n = 23,637) and a comparison cohort of mothers matched by maternal age, parity, and infant's year of birth (n = 234,586).

EXPOSURES

Liveborn infant with a major congenital anomaly.

MAIN OUTCOMES AND MEASURES

The primary outcome was mothers' employment status, stratified by their child's age. Employment status was categorized as employed, outside the workforce (on temporary leave, holding a flexible job, or pursuing education), or unemployed; the number of weeks in each category was measured over time. The secondary outcome was time to receipt of a disability pension, which in Denmark implies permanent exit from the labor market. We used a negative binomial regression model to estimate the number of weeks in each employment category, stratified by the child's age (i.e., 0-1 year, > 1-6 years, 7-13 years, 14-18 years). A Cox proportional hazards regression model was used to compute hazard ratios as a measure of the relative risk of receiving a disability pension. Rate ratios and hazard ratios were adjusted for maternal demographics, pregnancy history, health, and infant's year of birth.

RESULTS

During 1-6 years after delivery, MCMCAs were outside the workforce for a median of 50 weeks (IQR, 6-107 weeks), while members of the comparison cohort were outside the workforce for a median of 48 weeks (IQR, 4-98 weeks), corresponding to an adjusted rate ratio [ARR] of 1.05 (95% confidence interval [CI], 1.04-1.07). During the first year after delivery, MCMCAs were more likely to be employed than mothers in the comparison cohort (ARR, 1.08; 95% CI, 1.06-1.10). At all timepoints thereafter, MCMCAs had a lower rate of workforce participation. The rate of being outside the workforce was 5% higher than mothers in the comparison cohort during 1-6 years after delivery (ARR, 1.05; 95% CI, 1.04-1.07), 9% higher during 7-13 years after delivery (ARR, 1.09; 95% CI, 1.06-1.12), and 12% higher during 14-18 years after delivery (ARR, 1.12; 95% CI, 1.07-1.18). Overall, MCMCAs had a 20% increased risk of receiving a disability pension during follow-up than mothers in the matched comparison cohort [incidence rates 3.10 per 1000 person-years (95% CI, 2.89-3.32) vs. 2.34 per 1000 person-years (95% CI, 2.29-2.40), adjusted hazard ratio, 1.20; 95% CI, 1.11-1.29].

CONCLUSION AND RELEVANCE

MCMCAs were less likely to participate in the Danish workforce, less likely to be employed, and more likely to receive disability pensions than mothers of unaffected children. The rate of leaving the workforce intensified as their affected children grew older. The high demands of caregiving among MCMCAs may have long-term employment consequences even in nations with comprehensive and heavily tax-supported childcare systems, such as Denmark.

Mental Health Conditions in Partners and Adult Children of Stroke Survivors

Importance

Family caregiving after critical illness has been associated with several adverse health outcomes, including various aspects of mental health, but research focusing specifically on family members of stroke survivors is limited.

Objectives

To examine the associations of stroke in a partner or parent with the risk of depression, substance use disorders, anxiety disorders, and self-harm or suicide.

Design, Setting, and Participants

This nationwide, population-based cohort study used data from Danish nationwide administrative and clinical registries (2004-2021). Participants included partners and adult children of survivors of stroke. Data analysis was performed from March to December 2023.

Exposure

Having a partner or parent who survived stroke.

Main Outcomes and Measures

The Aalen-Johansen estimator was used to compute propensity score-weighted 3-year absolute risks, risk differences, and risk ratios for depression, substance use disorders, anxiety disorders, and self-harm or suicide among partners or children of survivors of stroke compared with partners or children of survivors of myocardial infarction (MI) and matched individuals from the general population.

Results

The study included a total of 1 923 732 individuals: 70 917 partners of stroke survivors (median [IQR] age, 68 [59-76] years; 46 369 women [65%]), 70 664 partners of MI survivors (median [IQR] age, 65 [55-73] years; 51 849 women [73%]), 354 570 partners of individuals from the general population (median [IQR] age, 68 [59-76] years; 231 833 women [65%]), 207 386 adult children of stroke survivors (median [IQR] age, 45 [36-52] years; 99 382 women [48%]), 183 309 adult children of MI survivors (median [IQR] age, 42 [33-49] years; 88 078 women [48%]), and 1 036 886 adult children of individuals from the general population (median [IQR] age, 45 [36-52] years; 496 875 women [48%]). Baseline characteristics were well balanced across cohorts after propensity score weighting. Among partners of stroke survivors, the 3-year absolute risk was 1.0% for depression, 0.7% for substance use disorders, 0.3% for anxiety disorders, and 0.04% for self-harm or suicide. Risk ratio point estimates for the assessed outcomes ranged from 1.14 to 1.42 compared with the general population and from 1.04 to 1.09 compared with partners of MI survivors. The elevated risk of depression in partners of stroke survivors was more pronounced after severe or moderate stroke than after mild stroke. Among adult children of stroke survivors, the 3-year absolute risk was 0.6% for depression, 0.6% for substance use disorders, 0.2% for anxiety disorders, and 0.05% for self-harm or suicide. Both absolute risks and risk ratios for adult children of stroke survivors were smaller than those reported in the partner analyses.

Conclusions and Relevance

In this cohort study of partners and adult children of stroke survivors, risks of several mental health conditions and self-harm or suicide were moderately higher compared with the general population and, to a lesser extent, partners and adult children of MI survivors. These findings highlight the potential consequences of stroke among family members, particularly partners, and its findings may possibly serve as a quantitative foundation for the development of future stroke rehabilitation services.

Congenital Tooth Agenesis and Risk of Early-Onset Cancer

Importance

There is some evidence that tooth agenesis (congenital absence of 1 or more teeth) is associated with cancer risk, especially carcinomas of the colon and ovaries, but results of previous studies are conflicting, and associations have not yet been evaluated in a population-based setting.

Objective

To examine the association between tooth agenesis and specific cancer types before 40 years of age.

Design, Setting, and Participants

This population-based cohort study used linking data from nationwide registries in Denmark to assess all Danish live-born singletons born from January 1, 1977, to December 31, 2018, and followed up for up to 40 years. Data were analyzed from January through June 2023.

Exposure

Tooth agenesis as documented by the Danish Central Registry of Odontology (Danish municipal pediatric dental care) from January 1, 1988, to December 31, 2018, and from hospital encounters in the Danish National Patient Registry within the entire study period.

Main Outcome and Measures

The primary outcome was first cancer diagnosis before 40 years of age obtained from the Danish Cancer Registry. Associations between tooth agenesis and specific cancers were estimated by Cox proportional hazards regression as hazard ratios (HRs) with 95% CIs. Analyses were split into age groups: younger than 1 year, 1 to younger than 3 years, 3 to younger than 10 years, 10 to younger than 20 years, 20 to younger than 30 years, and 30 to younger than 40 years. Associations with nonsyndromic tooth agenesis were evaluated after exclusion of individuals with known syndromes.

Results

Among 2 501 715 included individuals (1 284 292 [51.3%] male), 70 288 (2.8%) had a diagnosis of tooth agenesis (mean [SD] age at diagnosis, 13.2 [4.1] years) and 26 308 (1.1%) had a diagnosis of early-onset cancer within the study period; 778 individuals had co-occurrence of tooth agenesis and cancer. Overall, tooth agenesis was positively associated with several cancer types, including neuroblastoma (age 1 to <3 years; HR, 4.20; 95% CI, 2.24-7.88), nephroblastoma (age 1 to <3 years; HR, 4.59; 95% CI, 2.37-8.91), hepatoblastoma (age 1 to <3 years; HR, 7.10; 95% CI, 2.70-18.68), osteosarcoma (age 10 to <20 years; HR, 2.19; 95% CI, 1.11-4.32), colorectal carcinomas (age 30 to <40 years; HR, 2.81; 95% CI, 1.38-5.71), and carcinomas of bladder (age 20 to <30 years; HR, 3.35; 95% CI, 1.35-8.30).

Conclusions and Relevance

This cohort study found associations between congenital tooth agenesis and several cancer types, from childhood to early adulthood. Further evaluation of these associations is needed to assess possible clinical implications.

Impact of type 2 diabetes on complications after primary breast cancer surgery: Danish population-based cohort study

BACKGROUND

Knowledge is sparse on the impact of type 2 diabetes (T2D) on surgical outcomes after breast cancer surgery. This study investigated the association between T2D and risk of complications after primary breast cancer surgery, and evaluated the biological interaction between T2D and co-morbidities.

METHODS

Using the Danish Breast Cancer Group clinical database, a cohort of all Danish women diagnosed with early-stage breast cancer during 1996-2022 was created. All patients underwent mastectomy or breast-conserving surgery. Information on prevalent T2D was collected from Danish medical and prescription registries. Surgical complications were defined as hospital diagnoses for medical or surgical complications developing within 30 days after primary breast cancer surgery. The 30-day cumulative incidence proportion of complications was calculated, and Cox regression was used to estimate HRs. Interaction contrasts were computed to determine the additive interaction between T2D and co-morbidities on the incidence rate of complications.

RESULTS

Among 98 589 women with breast cancer, 6332 (6.4%) had T2D at breast cancer surgery. Overall, 1038 (16.4%) and 9861 (10.7%) women with and without T2D developed surgical complications, yielding cumulative incidence proportions of 16 (95% c.i. 15 to 17) and 11 (10 to 11)% respectively, and a HR of 1.43 (95% c.i. 1.34 to 1.53). The incidence rate of surgical complications explained by the interaction of T2D with moderate and severe co-morbidity was 21 and 42%, respectively.

CONCLUSION

Women with breast cancer and T2D had a higher risk of complications after primary breast cancer surgery than those without T2D. A synergistic effect of T2D and co-morbidity on surgical complications can explain this association.

Long-term cardiovascular events, graft failure, and mortality in kidney transplant recipients

BACKGROUND

Kidney transplant recipients are at increased risks of cardiovascular events, but contemporary risk estimates are sparse. Using the Danish nationwide administrative databases, we quantified 1- and 5-year risks of cardiovascular disease and kidney failure among all first-time kidney transplant recipients (2005-2018) and age- and sex-matched controls (1:10 ratio).

METHODS

Cumulative 1- and 5-year incidence of cardiovascular events (myocardial infarction, stroke, or heart failure), kidney failure (re-transplantation or need for dialysis >30 days post-transplant), and mortality following transplantation were calculated until maximally Dec 31, 2018.

RESULTS

A total of 2,565 kidney transplant recipients (median age 50.5 [25-75th percentile 40.2-60.7] years, 37 % females) and 25,650 controls were included. 1-year cumulative incidence of myocardial infarction, stroke, or heart failure was 2.6 % (95 % confidence interval 1.9 %-3.2 %) among kidney transplant recipients versus 0.5 % (0.4 %-0.5 %) in controls. Cumulative 5-year risk estimates for the same endpoints were 8.3 % (7.1 %-9.5 %) for the transplant patients, and 2.6 % (2.3 %-2.8 %) among controls, respectively. For the kidney transplant cohort, cumulative mortality was 2.2 % (1.7 %-2.8 %) and 10.3 % (9.0 %-11.6 %) at 1- and 5 years, respectively, versus 0.5 % (0.4 %-0.6 %) and 3.0 % (2.7 %-3.2 %) for controls. The cumulative incidence of dialysis and re-transplantation was 6.1 % (5.2 %-7.1 %) at 1 year and 16.3 % (14.7 %-17.9 %) at 5 years, respectively.

CONCLUSIONS

Despite the benefits of transplantation, kidney transplant recipients continue to have significant long-term cardiovascular disease, end-stage kidney disease, and mortality risks even with contemporary medical management. Better cardiovascular preventive strategies are warranted to improve prognosis in this segment of patients.

Primary autoimmune haemolytic anaemia is associated with increased risk of ischaemic stroke: A binational cohort study from Denmark and France

Primary autoimmune haemolytic anaemia (AIHA) causes the destruction of red blood cells and a subsequent pro-thrombotic state, potentially increasing the risk of ischaemic stroke. We investigated the risk of ischaemic stroke in patients with AIHA in a binational study. We used prospectively collected data from nationwide registers in Denmark and France to identify cohorts of patients with primary AIHA and age- and sex-matched general population comparators. We followed the patient and comparison cohorts for up to 5 years, with the first hospitalization of a stroke during follow-up as the main outcome. We estimated cumulative incidence, cause-specific hazard ratios (csHR) and adjusted for comorbidity and exposure to selected medications. The combined AIHA cohorts from both countries comprised 5994 patients and the 81 525 comparators. There were 130 ischaemic strokes in the AIHA cohort and 1821 among the comparators. Country-specific estimates were comparable, and the overall adjusted csHR was 1.36 [95% CI: 1.13-1.65], p = 0.001; the higher rate was limited to the first year after AIHA diagnosis (csHR 2.29 [95% CI: 1.77-2.97], p < 10-9 ) and decreased thereafter (csHR 0.89 [95% CI: 0.66-1.20], p = 0.45) (p-interaction < 10-5 ). The findings indicate that patients diagnosed with primary AIHA are at higher risk of ischaemic stroke in the first year after diagnosis.

The Danish Nationwide Electrocardiogram (ECG) Cohort

The electrocardiogram (ECG) is a non-invasive diagnostic tool holding significant clinical importance in the diagnosis and risk stratification of cardiac disease. However, access to large-scale, population-based digital ECG data for research purposes remains limited and challenging. Consequently, we established the Danish Nationwide ECG Cohort to provide data from standard 12-lead digital ECGs in both pre- and in-hospital settings, which can be linked to comprehensive Danish nationwide administrative registers on health and social data with long-term follow-up. The Danish Nationwide ECG Cohort is an open real-world cohort including all patients with at least one digital pre- or in-hospital ECG in Denmark from January 01, 2000, to December 31, 2021. The cohort includes data on standardized and uniform ECG diagnostic statements and ECG measurements including global parameters as well as lead-specific measures of waveform amplitudes, durations, and intervals. Currently, the cohort comprises 2,485,987 unique patients with a median age at the first ECG of 57 years (25th-75th percentiles, 40-71 years; males, 48%), resulting in a total of 11,952,430 ECGs. In conclusion, the Danish Nationwide ECG Cohort represents a novel and extensive population-based digital ECG dataset for cardiovascular research, encompassing both pre- and in-hospital settings. The cohort contains ECG diagnostic statements and ECG measurements that can be linked to various nationwide health and social registers without loss to follow-up.