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

Time-dependent incidence and risk for myocardial infarction in patients with alcoholic cirrhosis

BACKGROUND

It remains unsettled whether alcoholic cirrhosis is a risk factor for myocardial infarction (MI).

METHODS

We used data from nationwide healthcare registries to study all Danes diagnosed with alcoholic cirrhosis in 1996-2014, and five controls were matched to each of them on gender and age. We excluded everyone with ischaemic heart disease and used Cox regression to estimate the incidence rate ratio of MI adjusted for potential cardiovascular confounders. Further, we described the MI-risk with non-MI death as a competing risk.

RESULTS

We included 22 867 patients (67% men) with a median age of 57 years. During the first year of follow-up, their incidence rate ratio of MI was increased to 1.24 (95% CI: 0.94-1.62), driven by the effect among women (2.13, 95% CI: 1.17-3.87) and those with most severe cirrhosis (1.32, 95% CI: 0.91-1.90). After the first year, the overall incidence rate ratio fell to (0.89, 95% CI: 0.76-1.05). Patients were more likely to die from non-MI causes (33.7% vs 1.0%), which protected them against MI. The overall 1-year MI-risk was similar in patients and controls: 0.38% (95% CI: 0.30-0.47%) vs 0.34% (95% CI: 0.31-0.38%). After five years of follow-up, male patients had lower MI-risk than their controls, whereas women with cirrhosis had an increased MI-risk throughout follow-up.

CONCLUSIONS

The incidence rate of MI was increased the first year following a diagnosis of alcoholic cirrhosis, in particular in women and those with most severe liver disease. Due to the competing risk of non-MI mortality, the MI-risk was not increased.

Alanine Aminotransferase and 20-Year Risk of Major Chronic Diseases and Death in a Healthy Cohort Aged 30 to 49 Years

Purpose

Alanine aminotransferase is the most frequently used marker of liver cell injury. We examined the association between alanine aminotransferase levels and long-term absolute risks of morbidity and mortality in healthy Danish people aged 30-49 years.

Patients and Methods

We divided 671 healthy participants from the Ebeltoft Health Promotion Project into four categories based on their baseline alanine aminotransferase values: low (≤10U/l), medium-low (men: 11-34U/l, women: 11-22U/l), medium-high (men: 35-69U/l, women: 23-44U/l) and high (men: ≥70U/l, women: ≥45U/l), and followed them through Danish healthcare registries for up to 20 years. We examined mortality and absolute risks of liver disease, overall cancer, ischemic heart disease, and diabetes.

Results

The risk of any cancer was highest for participants with "low alanine aminotransferase" or "high alanine aminotransferase" (20-year risk: 17.2% [95% confidence interval (CI): 6.3-32.7%] and 18.2% [95% CI: 5.7-36.3%], respectively). The risk of diabetes was highest for participants with "medium-high alanine aminotransferase" or "high alanine aminotransferase" (20-year risk: 12.1% [95% CI: 7.3-18.3%] and 9.1% [95% CI: 1.6-25.1%], respectively). Participants with "high alanine aminotransferase" had the highest 20-year risk of liver disease (20-year risk: 13.6% [95% CI: 3.4-30.9%], while it was 1.0% or less in the other groups). The chance of being alive after 20 years without having been diagnosed with liver disease, cancer, ischemic heart disease, or diabetes was lowest in the "high alanine aminotransferase" group (50% [95% CI: 28-68%]) and 72-79% in the other groups.

Conclusion

Our findings suggest that persons with high or abnormally low alanine aminotransferase measurements are at increased long-term risk of several chronic diseases.

The Validity of Registered Synchronous Peritoneal Metastases from Colorectal Cancer in the Danish Medical Registries

Introduction

Treatment options for peritoneal metastases (PM) from colorectal cancer (CRC) have increased, their efficiency should be monitored. For this purpose, register-based data on PM can be used, if valid.

Purpose

We aimed to evaluate the completeness and positive predictive value (PPV) of synchronous peritoneal metastases (S-PM) registered among CRC patients in the Danish National Patient Register (DNPR) and/or the Danish National Pathology Register (the DNPatR) using the Danish Colorectal Cancer Group database (DCCG) as a reference.

Patients and Methods

We identified Danish patients with newly diagnosed primary CRC in the DCCG during 2014–2015. S-PM were routinely registered in the DCCG. We excluded patients with non-CRC cancers and identified S-PM using all three registries. We estimated the completeness and the PPV of registered S-PM in the DNPR, the DNPatR and the DNPR and/or the DNPatR (DNPR/DNPatR) in combination using the DCCG as the reference. We stratified by age, gender, WHO performance status, tumour location and distant metastases to liver and/or lungs.

Results

We identified 9142 patients with CRC in DCCG. In DCCG, 366 patients were registered with S-PM, among whom 213 in DCCG only, whereas 153 in DCCG and in at least one of DNPR and/or DNPatR. In DNPR/DNPatR, S-PM was registered with a completeness of 42% [95% CI: 37–47] and a PPV of 60% [95% CI: 54–66]. In the DNPR only, the completeness was 32% [95% CI: 27–37] and the PPV 57% [95% CI: 50–64]. The completeness in the DNPatR was 19% [95% CI: 15–23] and the PPV was 76% [95% CI: 68–85]. In the DNPR/DNPatR patients aged <60 years (57% [95% CI: 46–69]), patients with WHO performance status 0 (46% [95% CI: 37–54]) and patients with no distant metastases (58% [95% CI: 50–65]) were registered with a higher completeness.

Conclusion

Our algorithm demonstrates that the DNPR/DNPatR captures less than half of CRC patients with S-PM. Potential candidates for curative treatment options are registered with a higher completeness. Clinicians should be encouraged to register the presence of S-PM to increase the validity of register-based S-PM data.

Neonatal Vitamin D Status and Risk of Asthma in Childhood: Results from the D-Tect Study

Background: low vitamin D status in pregnancy can influence the offspring’s lung function and contribute to childhood asthma development. The objective of this study was to examine the influence of neonatal vitamin D status on the development of asthma among children age 3–9 years in a large population sample. Method: in a case-cohort study utilizing a Danish biobank and register data we examined the association between neonatal 25-hydroxyvitamin D₃ (25(OH)D₃) concentrations and incidence of asthma among children aged 3–9 years. Cases of asthma (n = 911) were randomly selected among all cases of asthma in the Danish National Patient Register from children born between 1992 and 2002. The sub-cohort (n = 1423) was randomly selected among all children born in the same period. We used a weighted Cox proportional hazard model assessing the hazard of first asthma diagnoses by quintiles of 25(OH)D₃. Results: the median 25(OH)D3 (interquartile range) for asthma cases was 23 nmol/L (14–35) and the sub-cohort 25 nmol/L (14–40). The hazard ratio for developing asthma between ages 3 and 9 years was lower for children in the fifth quintile of neonatal 25(OH)D₃ compared to children in the first quintile, both in the unadjusted (0.61 95% CI: 0.46–0.80) and adjusted (0.55 95% CI: 0.39–0.77) analyses. Conclusion: the results from our study suggest that higher neonatal vitamin D concentration may reduce the risk of developing childhood asthma at ages 3–9 years, indicating that neonatal vitamin D status as a proxy of vitamin D status during the prenatal period is important for normal immune- and lung development.

Long-term patient satisfaction and durability of laparoscopic anti-reflux surgery in a large Danish cohort: study protocol for a retrospective cohort study with development of a novel scoring system for patient selection

INTRODUCTION

Laparoscopic anti-reflux surgery is standard of care in surgical treatment of gastro-oesophageal reflux disease and is not without risks of adverse effects, including disruption of the fundoplication and postfundoplication dysphagia, in some cases leading to reoperation. Non-surgical factors such as pre-existing anxiety or depression influence postoperative satisfaction and symptom relief. Previous studies have focused on a short-term follow-up or only certain aspects of disease, such as reoperation or postoperative quality of life. The aim of this study is to evaluate long-term patient-satisfaction and durability of laparoscopic anti-reflux surgery in a large Danish cohort using a comprehensive multimodal follow-up, and to develop a clinically applicable scoring system usable in selecting patients for anti-reflux surgery.

METHODS AND ANALYSIS

The study is a retrospective cohort study utilising data from patient records and follow-up with patient-reported quality of life as well as registry-based data. The study population consists of all adult patients having undergone laparoscopic anti-reflux surgery at The Department of Surgery, Kolding Hospital, a part of Lillebaelt Hospital Denmark in an 11-year period. From electronic records; patient characteristics, preoperative endoscopic findings, reflux disease characteristics and details on type of surgery, will be identified. Disease-specific quality of life and dysphagia will be collected from a patient-reported follow-up. From Danish national registries, data on comorbidity, reoperative surgery, use of pharmacological anti-reflux treatment, mortality and socioeconomic factors will be included. Primary outcome of this study is treatment success at follow-up.

ETHICS AND DISSEMINATION

Study approval has been obtained from The Danish Patient Safety Agency, The Danish Health Data Authority and Statistics Denmark, complying to Danish and EU legislation. Inclusion in the study will require informed consent from participating subjects. The results of the study will be published in peer-reviewed medical journals regardless of whether these are positive, negative or inconclusive.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov (NCT03959020).

Application of the Adaptive Validation Substudy Design to Colorectal Cancer Recurrence

Background

Among men and women diagnosed with colorectal cancer (CRC), 20-50% will develop a cancer recurrence. Cancer recurrences are not routinely captured by most population-based registries; however, linkage across Danish registries allows for the development of predictive models to detect recurrence. Successful application of such models in population-based settings requires validation against a gold standard to ensure the accuracy of recurrence identification.

Objective

We apply a recently developed validation study design for prospectively collected validation data to validate predicted CRC recurrences against gold standard diagnoses from medical records in an actively followed cohort of CRC patients in Denmark.

Methods

We use a Bayesian monitoring framework, traditionally used in clinical trials, to iteratively update classification parameters (positive and negative predictive values, and sensitivity and specificity) in an adaptive validation substudy design. This design allows determination of the sample size necessary to estimate the corresponding parameters and to identify when validation efforts can cease based on predefined criteria for parameter values and levels of precision.

Results

Among 355 men and women diagnosed with CRC in Denmark and actively followed semi-annually, there were 63 recurrences diagnosed by active follow-up and 70 recurrences identified by a predictive algorithm. The adaptive validation design met stopping criteria for the classification parameters after 120 patients had their recurrence information validated. This stopping point yielded parameter estimates for the classification parameters similar to those obtained when the entire cohort was validated, with 66% less patients needed for the validation study.

Conclusion

In this proof of concept application of the adaptive validation study design for outcome misclassification, we demonstrated the ability of the method to accurately determine when sufficient validation data have been collected. This method serves as a novel validation substudy design for prospectively collected data with simultaneous implementation of a validation study.

The Positive Predictive Value of Hip Fracture Diagnoses and Surgical Procedure Codes in the Danish Multidisciplinary Hip Fracture Registry and the Danish National Patient Registry

Aim

The health-care databases may be a valuable source for epidemiological research in hip fracture surgery, if the diagnoses are valid. We examined the validity of hip fracture diagnoses and surgical procedure codes in the Danish Multidisciplinary Hip Fracture Registry (DMHFR) and the Danish National Patient Registry (DNPR) by calculating the positive predictive value (PPV).

Methods

We identified a random sample of 750 hip fracture patients registered in the DMHFR between 2014 and 2017. Diagnoses have been coded by the 10^th revision of the International Classification of Diseases, while procedures have been coded by the Nordic Medico-Statistical Committee classification in the DNPR and directly transferred to the DMHFR. Using the surgical procedure description from the medical record as gold standard, we estimated the PPV of the hip fracture diagnoses and surgical procedure codes in the DMHFR and the DNPR with 95% confidence interval (CIs).

Results

The PPV was 90% (95% CI: 86%-93%) for fracture of the neck of femur, 92% (95% CI: 87%-95%) for trochanteric fracture, and 83% (95% CI: 78%-88%) for subtrochanteric fracture. Joining trochanteric and subtrochanteric fracture resulted in a PPV of 97% (95% CI: 95%-98%). Procedure codes had a PPV of 100% for primary prosthetic replacement and internal fixation with intramedullary nail, 96% (95% CI: 85%-99%) for internal fixation using screws alone, 91% (95% CI: 84%-96%) for internal fixation using plates and screws, and 89% (95% CI: 83%-94%) for internal fixation with other or combined methods. Stratifying by age group, gender, hospital type and calendar year of surgery showed similar results as the overall PPV estimates.

Conclusion

Our findings indicate a high quality of the hip fracture diagnoses and corresponding procedure codes in the DMHFR and the DNPR, with a majority of PPVs above 90%. Thus, the DMHFR and the DNPR are a valuable data source on hip fracture for epidemiological research.

Syncope as a sign of occult cancers: a population-based cohort study

BACKGROUND

We examined if syncope was a marker of an occult cancer by comparing the risk in patients with a syncope episode with that of the general population.

METHODS

Using Danish population-based medical registries, we identified all patients diagnosed with syncope during 1994-2013 and followed them until a cancer diagnosis, emigration, death or end of follow-up, whichever came first. We computed cumulative risks and standardised incidence ratios (SIR) with 95% confidence intervals (CI).

RESULTS

Among 208,361 patients with syncope, 20,278 subsequent cancers were observed. The 6-month cumulative risk of any cancer was 1.2%, increasing to 17.9 % for 1-20 years of follow-up. The highest cumulative risks after 6 months of follow-up were lung cancer (0.2%), colorectal cancer (0.2%), prostate cancer (0.1%) and brain cancer (0.1%). The 6-month SIR were 2.7 (95% CI: 2.4-3.0) for lung cancer, 2.0 (95% CI: 1.8-2.2) for colorectal cancer, 1.7 (95% CI: 1.5-1.9) for prostate cancer and 10.0 (95% CI: 8.6-11.4) for brain cancer.

CONCLUSIONS

Syncope was a weak marker of an occult cancer. In short-term the highest cumulative risks were observed for lung, colorectal, prostate and brain cancers. An aggressive search for occult cancer in a patient with syncope is probably not warranted.

The interaction effect of cardiac and non-cardiac comorbidity on myocardial infarction mortality: A nationwide cohort study

BACKGROUND

Whether the prognostic impact of comorbidity on myocardial infarction (MI) mortality is due to comorbidity alone or/and its interaction effect is unknown.

METHODS

We used Danish medical registries to conduct a nationwide cohort study of all first-time MIs during 1995-2016 (n = 179,515) and a comparison cohort matched on age, sex, and individual comorbidities (n = 880,347). We calculated age-standardized 5-year all-cause mortality rates. Interaction was examined on an additive scale by calculating interaction contrasts (difference in rate differences).

RESULTS

Among individuals without comorbidity, the 30-day mortality rate per 1000 person-years was 1851 (95% CI: 1818-1884) for MI patients and 22 (21-24) for comparison cohort members (rate difference = 1829). For individuals with low comorbidity, corresponding baseline mortality rates were 2498 (2436-2560) in the MI and 54 (50-57) in the comparison cohort (rate difference = 2444). The interaction contrast (616) indicated that the interaction accounted for 25% (616/2498) of the total 30-day mortality rate in MI patients with low comorbidity. This percentage increased further for moderate (35%) and severe (45%) comorbidity levels. Absolute and relative interaction effects were largest within the first 30 days and younger individuals. Dose-response patterns were also observed during 31-365 days and 1-5 years of follow-up (p-values for trends<0.002). The interaction differed substantially between individual types of cardiac and non-cardiac comorbidities.

CONCLUSION

Cardiac and non-cardiac comorbidities interact with MI to increase short- and long-term mortality beyond that explained by their additive effects. The interaction had a dose-response relation with comorbidity burden and a magnitude of clinical importance.

The Danish Multidisciplinary Hip Fracture Registry 13-Year Results from a Population-Based Cohort of Hip Fracture Patients

AIM OF THE REGISTRY

The aim of the Danish Multidisciplinary Hip Fracture Registry (DMHFR) is to collect data on processes of treatment, nursing care and rehabilitation as well as outcomes for patients with hip fracture in Denmark, and thereby monitor and improve the quality.

STUDY POPULATION

Hip fracture patients at age 65 or older that have undergone surgery with arthroplasty or internal fixation since 2004.

MAIN VARIABLES

DMHFR collects quality indicators and descriptive variables. Quality indicators include eight process performance measures within treatment, nursing care and rehabilitation, reflecting recommendations from the national clinical guideline for hip fracture patients, and three outcome measures including survival within 30-days, unplanned acute readmission within 30 days and reoperation within 2 years. Descriptive variables include a number of patient- and surgery-related characteristics. All data are collected prospectively.

RESULTS

By the end of 2018, the DMHFR included 86,438 hip fracture patients. Since 2006, all hospital departments in Denmark, treating patients with hip fracture, have reported improvement in quality of care and improvement in survival, and reoperation over time as well as high completeness of variables registration.

CONCLUSION

The DMHFR is a well-established nationwide clinical registry, which plays a key role for monitoring and improving hip fracture care in Denmark. The registry can further be linked to a range of other nationwide registries in order to answer a number of relevant clinical research questions.

Exploring Functional Impairment in Light of Prolonged Grief Disorder: A Prospective, Population-Based Cohort Study

Background: Functional impairment is essential in the diagnostic criteria for prolonged grief disorder (PGD) in the ICD-11. It refers to the negative impact on everyday life, including inability to maintain the usual level of functioning. We aimed to assess the extent of functional impairment, emotion-related role limitation, and impaired social functioning before and after bereavement, and to explore associations with PGD, as measured by the 13-item Prolonged Grief Scale (PGD_PG13). Method: Relatives of terminally ill patients (n = 1,622) completed a questionnaire before and after bereavement. The questionnaire assessed "overall functional impairment" (PG-13 item) and "aspects of functional impairment" measured by mean scores of the 36-item Short Form Survey (SF-36) subscales emotional role and social functioning (0: worst; 100: best). We analyzed associations between PGD_PG13 and functional impairment prior to bereavement using logistic regression models adjusted for age, gender, personal relation, education, time interval to patient's death, and pre-loss grief. Results: In total, 51% reported overall functional impairment before bereavement, 27% reported functional impairment at 6 months after bereavement, and 19% reported functional impairment at 3 years after bereavement. The mean emotional role score was 47.5 (95%CI: 45.4-49.7) before bereavement, increasing to 77.4 (95%CI: 75.7-79.0) at 3 years after bereavement, compared to 85.1 (95%CI: 77.6-92.6) in a reference sample. Mean social functioning score increased gradually reaching the mean of the reference sample at 3 years after bereavement. PGD_PG13 was present in 26% of those with overall functional impairment at 6 months after bereavement, decreasing to 11% at 3 years after bereavement. Pre-bereavement measures of emotional role and social functioning were associated with PGD_PG13at 6 months and 3 years after bereavement. Discussion: Overall functional impairment was prevalent as reflected in low scores on daily activities and social functioning compared to a reference sample. Functioning may be an important factor during caregiving and bereavement and pre-bereavement functional impairment was associated with PGD_PG13. Future studies should investigate if maintaining daily activities and social functioning before bereavement could be key in early supportive care. Moreover, the role of functional impairment in bereavement interventions should be explored.

'I Want the Whole Package'. Elderly Patients' Preferences for Follow-Up After Abnormal Cervical Test Results: A Qualitative Study

BACKGROUND

The incidence of cervical cancer peaks around the age of 75 years, and elderly patients are more frequently diagnosed with advanced-stage cervical cancer than younger patients. There is considerable practice variation regarding follow-up of elderly patients with abnormal cervical test results at risk of cervical cancer, both nationally and internationally, due to uncertainty about risks and benefits for this particular patient group. The treatment preferences of these patients are, however, poorly described in the current literature. The aim of this study was to explore elderly patients' experiences with abnormal cervical test results and preferences for follow-up.

MATERIALS AND METHODS

We performed focus group interviews with seventeen Danish patients aged 60-79 years who had undergone biopsy and colposcopy in gynaecological outpatient clinics or at private gynaecologists due to a positive human papillomavirus (HPV) test result and/or abnormal cytology. A focus group interview guide was designed to cover experiences with abnormal cervical test results, including realistic risk and benefit scenarios related to underdiagnosis and overtreatment. Data were analysed thematically using a phenomenological approach.

RESULTS

The patients were surprised that elderly could also have an HPV infection. Most preferred treatment and follow-up at the gynaecologist over continuous control visits at the general practitioner. In case of persistent HPV infection and cervical intraepithelial neoplasia, a quick solution including cone biopsy was preferred even if it carried a risk of overtreatment. The patients wanted clear recommendations and demonstrated considerable intolerance towards healthcare professionals' clinical uncertainty regarding optimum follow-up.

CONCLUSION

Most elderly patients wanted closure involving cone biopsy, and they expressed tolerance towards overtreatment to reduce their risk of cervical cancer. Thus, clinicians should present known risks and benefits to elderly patients facing risk of overtreatment after abnormal cervical test results.

Intake of dietary fibre, red and processed meat and risk of late-onset Chronic Inflammatory Diseases: A prospective Danish study on the "diet, cancer and health" cohort

Background: Human and animal studies support the involvement of diet in the development of CID -chronic inflammatory diseases such as inflammatory bowel disease, psoriasis, rheumatoid arthritis, psoriatic arthritis, and multiple sclerosis. Objective: This cohort study aimed to investigate the association between intake of fibre, red and processed meat, and occurrence of late-onset CID (50+ years of age) in the DCH: Danish Diet, Cancer and Health cohort. We hypothesised that risk of late-onset CID would be lower among those with high intake of fibre and/or low intake of meat compared to individuals with low fibre and/or high meat intake. Methods: The DCH recruited 56,468 individuals, aged 50-64 years, between 1993 and 1997. At recruitment, diet intake was registered using food frequency questionnaires as well as lifestyle factors in 56,075 persons. Exposure variables were generated as sex-adjusted tertiles of fibre and meat (g/day). Development of CIDs was identified in national registries. Hazard ratios (HR) of late-onset CIDs (adjusted for age, sex, energy intake, alcohol, smoking, education, comorbidity, and civil status) were estimated for all three exposure variables. Results: During follow-up of 1,123,754 years (median (Interquartile range) = 22.2 (20.1-23.1)), 1,758 (3.1%) participants developed at least one CID. The adjusted HRs for developing CID (low fibre 1.04 [0.89-1.22] and medium fibre 1.04 [0.91-1.18] (high fibre as reference), and medium meat 0.96 [0.86-1.09] and high meat 0.94 [0.82-1.07] (low meat as reference)) or the individual diseases were not statistically significant. Conclusion: This large study did not support that a high intake of fibre and/or a low intake of meat had a high impact on the risk of late-onset CID.

Injury from electric scooters in Copenhagen: a retrospective cohort study

OBJECTIVE

To analyse injuries related to manual and electric scooter use from January 2016 up to and including July 2019.

SETTING

Electric scooter rental services were launched in Denmark in January 2019. The services were provided by private companies. Although rules for handling and riding scooters have been established, no reports either before or after introduction of electric scooters anticipated the full extent of use, and injuries to riders and pedestrians.

PARTICIPANTS

All patient records mentioning manual or electric scooters. Records were reviewed, and data were stratified according to two groups: manual and electric scooters.

INTERVENTIONS

A predefined survey was completed in all cases where 'scooter' was present. This contained variables such as type of scooter, type of participant, mechanism of injury, acuity, intoxication, referral to treatment facility.

OUTCOME MEASURES

Among incidents involving scooters, summary statistics on continuous and categorical variables of interest were reported.

RESULTS

468 scooter-related injuries were recorded. We found that manual scooter riders were more likely to be children under the age of 15; fall alone-involving no other party; sustain contusions, sprains and lacerations; and bruise either their fingers or toes. Riders of electric scooters were likely to be 18-25 years, sustain facial bruising and lacerations requiring sutures, and be under the influence of alcohol or drugs. Non-riders of electric scooters were mostly elderly people who tripped over scooters, consequently sustaining moderate to severe injuries.

CONCLUSION

There were two different types of population sustaining injuries from manual and electric scooters, respectively. The proportion of non-riders injured by electric scooters were surprisingly large (17%), and while electric scooters are here to stay, several apparently preventable injuries occur as a result of reckless driving and discarded electric scooters. Current rules for usage might not prevent unnecessary accidents and secure traffic safety and the lives of older individuals.

Maternal diabetes during pregnancy and early onset of cardiovascular disease in offspring: population based cohort study with 40 years of follow-up

OBJECTIVE

To evaluate the associations between maternal diabetes diagnosed before or during pregnancy and early onset cardiovascular disease (CVD) in offspring during their first four decades of life.

DESIGN

Population based cohort study.

SETTING

Danish national health registries.

PARTICIPANTS

All 2 432 000 liveborn children without congenital heart disease in Denmark during 1977-2016. Follow-up began at birth and continued until first time diagnosis of CVD, death, emigration, or 31 December 2016, whichever came first.

EXPOSURES FOR OBSERVATIONAL STUDIES

Pregestational diabetes, including type 1 diabetes (n=22 055) and type 2 diabetes (n=6537), and gestational diabetes (n=26 272).

MAIN OUTCOME MEASURES

The primary outcome was early onset CVD (excluding congenital heart diseases) defined by hospital diagnosis. Associations between maternal diabetes and risks of early onset CVD in offspring were studied. Cox regression was used to assess whether a maternal history of CVD or maternal diabetic complications affected these associations. Adjustments were made for calendar year, sex, singleton status, maternal factors (parity, age, smoking, education, cohabitation, residence at childbirth, history of CVD before childbirth), and paternal history of CVD before childbirth. The cumulative incidence was averaged across all individuals, and factors were adjusted while treating deaths from causes other than CVD as competing events.

RESULTS

During up to 40 years of follow-up, 1153 offspring of mothers with diabetes and 91 311 offspring of mothers who did not have diabetes were diagnosed with CVD. Offspring of mothers with diabetes had a 29% increased overall rate of early onset CVD (hazard ratio 1.29 (95% confidence interval 1.21 to 1.37); cumulative incidence among offspring unexposed to maternal diabetes at 40 years of age 13.07% (12.92% to 13.21%), difference in cumulative incidence between exposed and unexposed offspring 4.72% (2.37% to 7.06%)). The sibship design yielded results similar to those of the unpaired design based on the whole cohort. Both pregestational diabetes (1.34 (1.25 to 1.43)) and gestational diabetes (1.19 (1.07 to 1.32)) were associated with increased rates of CVD in offspring. We also observed varied increased rates of specific early onset CVDs, particularly heart failure (1.45 (0.89 to 2.35)), hypertensive disease (1.78 (1.50 to 2.11)), deep vein thrombosis (1.82 (1.38 to 2.41)), and pulmonary embolism (1.91 (1.31 to 2.80)). Increased rates of CVD were seen in different age groups from childhood to early adulthood until age 40 years. The increased rates were more pronounced among offspring of mothers with diabetic complications (1.60 (1.25 to 2.05)). A higher incidence of early onset CVD in offspring of mothers with diabetes and comorbid CVD (1.73 (1.36 to 2.20)) was associated with the added influence of comorbid CVD but not due to the interaction between diabetes and CVD on the multiplicative scale (P value for interaction 0.94).

CONCLUSIONS

Children of mothers with diabetes, especially those mothers with a history of CVD or diabetic complications, have increased rates of early onset CVD from childhood to early adulthood. If maternal diabetes does have a causal association with increased CVD rate in offspring, the prevention, screening, and treatment of diabetes in women of childbearing age could help to reduce the risk of CVD in the next generation.

Vascular Diseases In Patients With Chronic Myeloproliferative Neoplasms - Impact Of Comorbidity

Background

Patients with chronic myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF), are at high risk of vascular complications. However, the magnitude of this is risk not well known and the possible effect of comorbidity is poorly understood.

Aim

Our aim was to compare the risk of vascular diseases in patients with MPNs and matched comparisons from the general population and to study the effect modification of comorbidity.

Methods

We followed 3087 patients with ET, 6076 with PV, 3719 with PMF or unspecified MPN, and age- and sex-matched general population comparisons to estimate the risks of cardiovascular diseases such as myocardial infarction and stroke. We computed 5-year cumulative incidences (risks) for vascular disease in patients with MPNs and comparisons as well as 1-year and 5-year risks, risk differences, and hazard ratios (HRs) for vascular diseases comparing rates in each group of patients with their comparison cohort by level of comorbidity based on the Charlson Comorbidity Index (CCI) [score of 0 (low comorbidity), of 1–2 (moderate comorbidity), and of >2 (severe comorbidity)], as well as other comorbid conditions.

Results

The overall 5-year risk of vascular disease ranged from 0.5% to 7.7% in patients with MPNs, which was higher than the risk in the general population. In the same period, the adjusted HRs for vascular disease were 1.3 to 3.7 folds higher in patients with MPNs compared to the general population. An increase in CCI score was associated with an equally increased rate of most types of vascular diseases during the first 5 years of follow-up in both MPN and comparisons.

Conclusion

Patients with MPNs have a higher risk of vascular diseases during the first 5 years than that of the general population; however, comorbidity modifies the rates similarly in MPN and in the general population.

Impact of the Charlson Comorbidity Index score on risk prediction by single-photon emission computed tomography myocardial perfusion imaging following myocardial infarction

Background

Comorbidity is common among patients with myocardial infarction (MI). We examined whether comorbidity level modified the single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI)-based prediction of 5-year risk of MI and all-cause death in patients with MI.

Methods

This cohort study included patients with prior MI having a SPECT MPI at Aarhus University Hospital, Denmark, 1999–2011. Using nationwide registries, we obtained information on comorbidity levels (low, moderate, and severe) and outcomes. We computed risk and hazard ratios (HRs) with 95% confidence intervals (CIs) for MI and all-cause death, comparing normal (no defects) versus abnormal scan (reversible and/or fixed defects) using Cox regression adjusting for sex, age, and comorbidity level.

Results

We identified 1,192 patients with MI before SPECT MPI. The 5-year risk for patients with normal versus abnormal scans were 11.7% versus 18.3% for MI, and 8.0% versus 13.2% for all-cause death, respectively. The overall 5-year adjusted HR (aHR) of MI was 1.56 (95% CI: 1.09–2.21), 1.33 (95% CI: 0.82–2.15) with low comorbidity, 1.39 (95% CI: 0.68–2.83) with moderate comorbidity, and 2.53 (95% CI: 1.14–5.62) with severe comorbidity. Similarly, the 5-year aHR for all-cause death was 1.39 (95% CI: 0.90–2.14) overall; 2.33 (95% CI: 0.79–6.84) with low comorbidity, 2.05 (95% CI: 0.69–6.06) with moderate comorbidity, and 1.07 (95% CI: 0.64–1.80) with severe comorbidity.

Conclusion

We conclude that comorbidity level may modify the 5-year risk prediction associated with an abnormal SPECT MPI scan in patients with previous MI.

Validity of ICD-10 diagnoses of overweight and obesity in Danish hospitals

Purpose

Health care databases may be a valuable source for epidemiological research in obesity, if diagnoses are valid. We examined the validity and completeness of International Classification of Diseases, 10th revision [ICD-10] diagnosis coding for overweight/obesity in Danish hospitals.

Patients and methods

We linked data from the Danish National Patient Registry on patients with a hospital diagnosis code of overweight/obesity (ICD-10 code E66) with computerized height and weight measurements made during hospital contacts in the Central Denmark Region Clinical Information System. We computed the positive predictive value (PPV) of the IDC-10 diagnosis of overweight/obesity, using a documented body mass index (BMI) ≥25 kg/m² as gold standard. We also examined the completeness of obesity/overweight diagnosis coding among all patients recorded with BMI ≥25 kg/m².

Results

Of all 19,672 patients registered with a first diagnosis code of overweight/obesity in the National Patient Registry, 17,351 patients (88.2%) had any BMI measurement recorded in the Central Denmark Region Clinical Information System, and 17,240 patients (87.6%) had a BMI ≥25 kg/m², yielding a PPV of 87.6% (95% CI: 87.2-88.1). The PPV was slightly higher for primary diagnosis codes of overweight/obesity: 94.1% (95% CI: 93.3-94.8) than for secondary diagnosis codes: 86.1% (95% CI: 85.6-86.6). The PPV increased with higher patient age: from 75.3% (95% CI: 73.8-76.9) in those aged 18-29 years to 94.7% (95% CI: 92.6-96.9) in patients aged 80 years and above. Completeness of obesity/overweight diagnosis coding among patients recorded with BMI ≥25 kg/m² was only 10.9% (95% CI: 10.8-11.0).

Conclusion

Our findings indicate a high validity of the ICD-10 code E66 for overweight/obesity when recorded; however, completeness of coding was low. Nonetheless, ICD-10 discharge codes may be a suitable source of data on overweight/obesity for epidemiological research.

Risk of cancer in patients with fecal incontinence

BACKGROUND

Fecal incontinence may be an early symptom of cancer, but its association with cancer remains unclear. We examined the risk of selected cancers, including colorectal cancer, other gastrointestinal cancers, hormone-related cancers, and lymphoma, in patients with fecal incontinence.

METHODS

Using Danish population-based registries, all patients with hospital-based diagnoses of fecal incontinence during 1995-2013 were identified. We calculated cumulative incidences of cancers. As a measure of relative risks, we computed standardized incidence ratios (SIRs), that is, the observed number of cancers relative to the expected number based on national incidence rates by sex, age, and calendar year.

RESULTS

Among 16 556 patients with fecal incontinence, the cumulative incidence of colorectal cancers, other gastrointestinal cancers, hormone-related cancers, and lymphoma each was less than 0.4% after 1 year. It increased to under 3% after 10 years. The SIR for any cancer during 19 years of follow-up was 1.12 [95% confidence interval (CI), 1.06-1.19]. The SIRs during the first year were 2.31 (95% CI, 1.65-3.13) for colorectal cancer, 1.56 (95% CI, 0.89-2.54) for other gastrointestinal cancers, 1.00 (95% CI, 0.72-1.35) for hormone-related cancers, and 2.02 (95% CI, 1.01-3.61) for lymphoma. Beyond 1 year, the SIR reached unity for other gastrointestinal cancers, hormone-related cancers, and lymphoma, while a reduced risk was observed for colorectal cancer (SIR = 0.77, 95% CI, 0.59-0.98).

CONCLUSIONS

Fecal incontinence was a marker of cancer, especially gastrointestinal cancers and lymphoma within 1 year, which presumably is driven partly by reverse causation. However, the absolute risks were low. Heightened diagnostic efforts may explain in part the increased short-term risk of colorectal cancers.

Pregnancy, Birth, Neonatal, and Postnatal Neurological Outcomes After Pregnancy With Migraine

BACKGROUND

Prevalence of migraine is high during the reproductive age. Although migraine often improves during pregnancy, the risk of adverse pregnancy, birth, neonatal, and neurological outcomes in mother and offspring remains poorly understood.

OBJECTIVE

To investigate the associations between maternal migraine and risks of adverse pregnancy outcomes in the mother, and birth, neonatal and postnatal outcomes in the offspring.

METHODS

We used Danish population registries to assemble a cohort of pregnancies among women with migraine and an age- and conception year-matched comparison cohort of pregnancies among women without migraine. The study period was 2005-2012. We computed adjusted prevalence ratios (aPRs) for pregnancy and birth outcomes and adjusted risk ratios (aRRs) for neonatal and postnatal outcomes, adjusting for age, preconception medical history, and preconception reproductive history.

RESULTS

We identified 22,841 pregnancies among women with migraine and 228,324 matched pregnancies among women without migraine. Migraine was associated with an increased risk of pregnancy-associated hypertension disorders (aPR: 1.50 [95% confidence interval (CI): 1.39-1.61]) and miscarriage (aPR: 1.10 [95% CI: 1.05-1.15]). Migraine was associated with an increased prevalence of low birth weight (aPR: 1.14 [95% CI: 1.06-1.23]), preterm birth (aPR: 1.21 [95% CI: 1.13-1.30]) and cesarean delivery (aPR: 1.20 [95% CI: 1.15-1.25]), but not of small for gestational age offspring (aPR: 0.94 [95% CI: 0.88-0.99]) and birth defects (aPR: 1.01 [95% CI: 0.93-1.09]). Offspring prenatally exposed to maternal migraine had elevated risks of several outcomes in the neonatal and postnatal period, including intensive care unit admission (aRR: 1.22 [95% CI: 1.03-1.45]), hospitalization (aRR: 1.12 [95% CI: 1.06-1.18]), dispensed prescriptions (aRR: 1.34 [95% CI: 1.24-1.45]), respiratory distress syndrome (aRR: 1.20 [95% CI: 1.02-1.42]), and febrile seizures (aRR: 1.27 [95% CI: 1.03-1.57), but not of death (aRR: 0.67 [95% CI: 0.43-1.04]) and cerebral palsy (aRR: 1.00 [95% CI: 0.51-1.94]).

CONCLUSIONS

Women with migraine and their offspring have greater risks of several adverse pregnancy outcomes than women without migraine.