Positive predictive value of first-time rheumatoid arthritis diagnoses and their serological subtypes in the Danish National Patient Registry

The risk of cancer in pediatric-onset immune-mediated inflammatory diseases - A nationwide study

BACKGROUND AND OBJECTIVES

Adult-onset immune-mediated inflammatory disease (IMID) increases the risk of several cancers. However, data on pediatric-onset IMID (pIMID) remains scarce. We estimated the long-term cancer risk in pIMID and the association between medical treatment and specific cancers.

METHODS

We used the nationwide Danish health registers to identify pIMID patients diagnosed from Jan 1, 1980 to Dec 31, 2018. Patients were matched with ten reference individuals based on age, sex, and residence. The primary exposure was pIMID, including autoimmune hepatitis, primary sclerosing cholangitis, Crohn's disease, ulcerative colitis, juvenile idiopathic arthritis, systemic lupus erythematosus, vasculitis, and connective tissue disease. Secondary exposures were immunomodulators and tumor necrosis factor-α antagonists (anti-TNFα). The primary outcome was cancer. Estimates are presented as hazard ratios adjusted for family income at diagnosis (AHR).

RESULTS

We included 12,664 pIMID patients and 109,274 reference individuals. Median follow-up time was 10.6 (interquartile range: 5.4-17.7) years for patients and 10.2 (interquartile range: 5.2-17.3) years for reference individuals. Patients with pIMID had a twofold higher cancer risk (AHR 2.2 [95 % confidence interval (CI): 1.8-2.6]) compared with reference individuals. Thiopurine treatment was associated with a higher risk of lymphoma (AHR 6.1 [95%CI: 2.2-16.8]) and skin cancer (AHR 6.1 [95%CI: 2.4-15.4]). Anti-TNFα treatment was associated with a higher risk of lymphoma (AHR 4.9 [95%CI: 1.1-22.6]).

CONCLUSIONS

We found an increased cancer risk in patients with pIMID followed into adulthood. Additionally, thiopurines and anti-TNFα were associated with increased lymphoma and skin cancer risks. This highlights the importance of individualized immunotherapy and cancer surveillance.

Incidence of seropositive and seronegative rheumatoid arthritis in Denmark: a nationwide population-based study

OBJECTIVE

To investigate and compare trends in incidence rates (IRs) of seropositive and seronegative rheumatoid arthritis (RA) in Denmark using various data sources for serostatus definition.

METHOD

This nationwide population-based cohort study was based on data from Danish healthcare and clinical quality registries between 2000 and 2018. Information on anti-cyclic citrullinated peptide and immunoglobulin M rheumatoid factor was obtained, and definitions of seropositivity according to the number of applied data sources were prespecified. Annual age- and sex-standardized IRs were calculated as the number of incident seropositive and seronegative cases, divided by the number of person-years (PY) in the general population in that given year.

RESULTS

An increasing temporal trend in IR of seropositive RA and a decreasing trend in seronegative RA were observed. The IRs were higher for seropositive RA than for seronegative RA from 2009 onwards, with a widening of the IR gap between 2009 and 2016 regardless of the definition of seropositivity. When combining laboratory- and physician-reported autoantibody information and ICD-10 codes, the IR of seropositive RA in 2018 was approximately twice that of seronegative RA, at 19.0 and 9.0 per 100 000 PY, respectively. The level of antibody testing increased significantly during the study period.

CONCLUSIONS

The IR of seropositive RA increased over time, whereas the IR of seronegative RA decreased. Temporal IR changes may be caused by a real change in the RA serology subtypes, an increase in autoantibody testing and availability, changes in registration practice over time, or a combination of these factors.

Paediatric-onset immune-mediated inflammatory disease is associated with an increased mortality risk-A nationwide study

BACKGROUND

Paediatric-onset immune-mediated inflammatory diseases (pIMID) show more aggressive phenotypes than when diagnosed in adults. However, data on mortality are often extrapolated from adult studies.

AIM

To estimate the effect of pIMID on mortality.

METHODS

In a population-based cohort study using the nationwide Danish healthcare registers, we included all patients diagnosed with pIMID in Denmark from 1980 to 2018. PIMID were defined as ICD codes indicative of autoimmune hepatitis, primary sclerosing cholangitis, Crohn's disease, ulcerative colitis, juvenile idiopathic arthritis, lupus erythematosus, or vasculitis registered before age 18 years. All-cause mortality was the primary outcome; cause-specific mortality was the secondary outcome. We used Cox survival analysis to estimate hazard ratios (HR), and Aalen survival analysis to estimate rate differences.

RESULTS

We included 11,581 individuals diagnosed with pIMID and 99,665 reference individuals, accounting for 1,371,994 person-years of follow-up. Median and interquartile (IQR) age at diagnosis was 12.6 (7.9-15.9) years. During follow-up, 152 patients with pIMID and 316 reference individuals died; adjusted HR (aHR) was 3.8 (95% confidence interval [CI] 3.1-4.7). This corresponded to 6.9 (95% CI: 5.3-8.5) additional deaths per 10,000 person-years. The strongest associations were found for gastrointestinal diseases (aHR 22.8; 95% CI 9.6-64.1), gastrointestinal cancers (aHR 19.2; 95% CI 5.0-74.2) and lymphoproliferative disorders (aHR 6.8; 95% CI 2.8-16.8).

CONCLUSION

Patients diagnosed with pIMID have a fourfold higher risk of mortality when followed into early adulthood compared with reference individuals. This underlines the severe disease course of pIMID and highlights the need for multidisciplinary care.

Temporal trends in mortality in patients with rheumatoid arthritis: a Danish population-based matched cohort study

OBJECTIVES

To investigate the 5-year all-cause mortality in patients with RA compared with the general population.

METHODS

This was a nationwide population-based matched cohort study. RA patients diagnosed between 1996 and the end of 2015 were identified using administrative heath registries and followed until the end of 2020 allowing 5 years of follow-up. Patients with incident RA were matched 1:5 on year of birth and sex with non-RA individuals from the Danish general population. Time-to-event analyses were performed using the pseudo-observation approach.

RESULTS

Compared with matched controls in 1996-2000, the risk difference for RA patients ranged from 3.5% (95% CI 2.7%, 4.4%) in 1996-2000 to -1.6% (95% CI -2.3%, -1.0%) in 2011-15, and the relative risk from 1.3 (95% CI 1.2, 1.4) in 1996-2000 to 0.9 (95% CI 0.8, 0.9) in 2011-15. The age-adjusted 5-year cumulative incidence proportion of death for a 60-year-old RA patient decreased from 8.1% (95% CI 7.3%, 8.9%) when diagnosed in 1996-2000 to 2.9% (95% CI 2.3%, 3.5%) in 2011-15, and for matched controls from 4.6% (95% CI 4.2%, 4.9%) to 2.1% (95% CI 1.9%, 2.4%). Excess mortality persisted in women with RA throughout the study period, while the mortality risk for men with RA in 2011-15 was similar to their matched controls.

CONCLUSIONS

Enhanced improvement in mortality was found in RA patients compared with matched controls, but for sex-specific differences excess mortality was only persistent in women with RA.

Older Adult-Onset of Inflammatory Bowel Diseases Is Associated With Higher Utilization of Analgesics: A Nationwide Cohort Study

INTRODUCTION

Patients with inflammatory bowel diseases (IBD) commonly require analgesic medications to treat pain, which may be associated with complications. We examined trends of analgesic use according to age at IBD onset.

METHODS

This nationwide cohort study included adults diagnosed with IBD between 1996 and 2021 in Denmark. Patients were stratified according to their age at IBD onset: 18-39 years (young adult), 40-59 years (adult), and older than 60 years (older adult). We examined the proportion of patients who received prescriptions for analgesic medications within 1 year after IBD diagnosis: strong opioids, tramadol, codeine, nonsteroidal anti-inflammatory drugs, and paracetamol. Multivariable logistic regression analysis was performed to examine the association between age at IBD onset and strong opioid prescriptions and the composite of strong opioid/tramadol/codeine prescriptions.

RESULTS

We identified 54,216 adults with IBD. Among them, 25,184 (46.5%) were young adults, 16,106 (29.7%) were adults, and 12,926 (23.8%) were older adults at IBD onset. Older adults most commonly received analgesic prescriptions of every class. Between 1996 and 2021, strong opioid, tramadol, and codeine prescriptions were stable, while paracetamol prescriptions increased and nonsteroidal anti-inflammatory drug prescriptions decreased. After multivariable logistic regression analysis, older adults had higher adjusted odds of receiving strong opioid prescriptions (adjusted odds ratio 1.95, 95% confidence interval 1.77-2.15) and the composite of strong opioid/tramadol/codeine prescriptions (adjusted odds ratio 1.93, 95% confidence interval 1.81-2.06) within 1 year after IBD diagnosis compared with adults.

DISCUSSION

In this nationwide cohort, older adults most commonly received analgesic prescriptions within 1 year after IBD diagnosis. Additional research is needed to examine the etiology and sequelae of increased analgesic prescribing to this demographic.

Mortality in heart failure with and without autoimmune disease

AIMS

Autoimmune diseases (AIDs) are associated with a higher risk of heart failure (HF). However, data on the prognosis of HF patients with a history of AID are limited. The aim was to investigate the rates of all-cause mortality and HF hospitalization in a large, nationwide cohort of patient with HF according to a history of 29 AIDs.

METHODS AND RESULTS

Using Danish nationwide registries, each HF patient (diagnosed 2000-18) with a history of AID was matched with four HF patients without AID by age, sex, and year of HF diagnosis. Rates of outcomes were compared by Cox regression models. The prevalence of AID in patients with HF was 10.7%. In total, 21 256 HF patients with a history of AID were matched with 85 024 HF patients without AID (median age 77 years; 58.9% female). During a median follow-up of 3.2 years, the incidence rates per 100 person-years for all-cause mortality were 17.1 (95% confidence interval, 16.9-17.4) and 14.4 (14.3-14.6) in patients with and without AID, respectively. The corresponding rates for HF hospitalization were 5.0 (4.9-5.1) and 5.2 (5.1-5.4), respectively. A history of AID was associated with higher rate of all-cause mortality [hazard ratio (HR) 1.14 (1.12-1.17)], but not HF hospitalization [HR 1.00 (0.96-1.04)] compared with no AID.

CONCLUSIONS

In a nationwide cohort study, patients with HF and a history of AID had a higher associated rate of mortality than those without a history of AID.

Rheumatoid arthritis and the risk of postpartum psychiatric disorders: a Nordic population-based cohort study

BACKGROUND

Postpartum psychiatric disorders (PPD) are common complications of childbirth. A common explanation for their development is that the psychological, hormonal, and immune changes associated with pregnancy and parturition may trigger psychiatric symptoms postpartum. Rheumatoid arthritis (RA) is characterized by abnormalities in the activity of the hypothalamic-pituitary-adrenal axis and of the immune system, but its association with PPD is unknown. We analyzed whether women with RA before childbirth have an increased risk of PPD.

METHODS

We conducted a large population-based cohort study including mothers of singleton births in the Danish (1995-2015), Finnish (1997-2013), and Swedish Medical Birth Registers (2001-2013) (N = 3,516,849). We linked data from the Medical Birth Registers with data from several national socioeconomic and health registers. Exposure was defined as having a diagnosis of RA before childbirth, while the main outcome was a clinical diagnosis of psychiatric disorders 90 days postpartum. We analyzed the association between RA and PPD using Cox proportional hazard models, stratified by a personal history of psychiatric disorders.

RESULTS

Among women without a history of psychiatric disorders, the PPD incidence rate was 32.2 in the exposed and 19.5 per 1000 person-years in the unexposed group; women with RA had a higher risk of overall PPD than their unexposed counterparts [adjusted hazard ratio (HR) = 1.52, 95% confidence intervals (CI) 1.17 to 1.98]. Similar associations were also observed for postpartum depression (HR = 1.65, 95% CI 1.09 to 2.48) and other PPD (HR = 1.59, 95% CI 1.13 to 2.24). Among women with a history of psychiatric disorders, the incidence rate of overall PPD was 339.6 in the exposed and 346.6 per 1000 person-years in the unexposed group; RA was not associated with PPD. We observed similar associations between preclinical RA (RA diagnosed after childbirth) and PPD to those corresponding to clinical RA.

CONCLUSIONS

Rheumatoid arthritis was associated with an increased PPD risk in women without, but not in those with a psychiatric history. If our findings are confirmed in future studies, new mothers with RA may benefit from increased surveillance for new-onset psychiatric disorders postpartum.

School performance and psychiatric comorbidity in childhood absence epilepsy: A Danish cohort study

The aim was to determine school performance and psychiatric comorbidity in children with childhood absence epilepsy (CAE). We reviewed the medical records in children with ICD-10 codes for idiopathic generalized epilepsy before 18 years of age, and pediatric neurologists confirmed the International League Against Epilepsy criteria for CAE were met. Control groups were the general pediatric population or children with non-neurological chronic disease. Outcomes were from nationwide and population-based registers on school performance and psychiatric comorbidity. We compared the mean grade point average using linear regression and estimated hazard ratios (HR) using Cox regression for the other outcomes. Analyses were adjusted for the child's sex, and year of birth, and parental highest education, receipt of cash benefits or early disability pension. We included 114 children with CAE with a median age at onset of 5.9 years (interquartile range = 4.5-7.3 years). Compared with both population controls and non-neurological chronically ill children, children with CAE had increased hazard of special needs education (HR = 2.7, 95% confidence interval (CI) = 1.8-4.1, p < 0.0001), lower grade point average at 9th grade by 1.7 grade points (95% CI = -2.5 to -1.0, p < 0.001), increased ADHD medicine use (HR = 4.4, 95% CI = 2.7-7.2, p < 0.001), increased sleep medicine use (HR = 2.7, 95% CI = 1.7-4.3, p < 0.001), and increased psychiatry visits (HR = 2.1, 95% CI = 1.1-4.0, p = 0.03). In conclusion, children with CAE have increased psychiatric comorbidity and a considerable proportion of these children receive special needs education in primary/secondary school, albeit insufficient to normalize their considerably lower grade point average in the 9th grade.

School performance and psychiatric comorbidity in juvenile absence epilepsy and juvenile myoclonic epilepsy: a Danish population-based cohort study

BACKGROUND

We aimed to determine school performance and psychiatric comorbidity in juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy (JME), and generalized tonic-clonic seizures (GTCS) alone.

METHODS

All children (< 18 years) fulfilled International League Against Epilepsy criteria after review of their medical records. Control groups were the pediatric background population or children with non-neurological chronic disease. Outcomes were on school performance and psychiatric comorbidity. We compared mean grade point averages using linear regression and estimated hazard ratios using Cox regression in the remaining analyses. We adjusted for the child's sex, age, and year of birth; and parental highest education, receipt of cash benefits or early retirement.

RESULTS

We included 92 JAE, 190 JME, 27 GTCS alone, 15,084 non-neurological chronic disease controls, and population controls. JAE had two times increased hazard for special needs education compared with age-matched population controls (hazard ratio 2.2, 95% CI = 1.1‒4.6, p = 0.03); this was not seen in JME. Compared with population controls, both JAE and JME had lower grade point average in secondary and high school (JME: 9th grade:  - 0.5 points, 95% CI = -0.9 to -0.06, p = 0.03; high school:  - 0.6 points, 95% CI = -1.3 to -0.1, p = 0.04), and 8% fewer JME and 15% fewer JAE attended high school. Both JME and JAE had higher hazard for redeeming sleep medication compared with non-neurological chronic disease; additionally, JAE had increased hazard for ADHD medicine redemptions.

CONCLUSIONS

Both JAE and JME had marginally poorer school performance; performance seemed worse in JAE than in JME. Both JAE and JME had increased use of sleep medication.

Employment, health visits, mental health, and mortality in parents with a chronically ill child: a Danish nationwide population-based cohort study

Chronic diseases in children can impact their parents; this may be overlooked in a clinical setting. Our aim was to investigate associations of chronic diseases in children with their parents' employment, health care utilization, mental health, and mortality. In a matched cohort study using nationwide and population-based data in Denmark, we included parents to children (< 18 years) with acute disseminated encephalomyelitis, multiple sclerosis, type 1 diabetes, inflammatory bowel disease, and rheumatoid arthritis/juvenile idiopathic arthritis during 2008-2015. The reference group was parents to unaffected children. Outcomes were parental employment (early retirement, cash benefits, income), health care utilization (e.g., general practitioner, or hospital visits), mental health (visits to psychiatry/psychology clinics, antidepressant drug redemptions), and mortality. We included 13,769 parents with a chronically ill child and 138,606 control parents. Annual income was unaffected for two-parent families after the child's disease onset, but two-parent families had increased hazard of early retirement of 25% (95% CI = 1.01-1.54; p = 0.04). Parents with a chronically ill child had (a) increased rate of antidepressant drug redemptions or psychology/psychiatry visits (hazard ratio 1.37; 95% CI = 1.28-1.46 at 1-year follow-up); (b) increased health care utilization, with an increased marginal mean in primary care of 1% (95% CI = 1.00-1.02; p = 0.005), hospital-affiliated visits of 19% (95% CI = 1.14-1.24; p < 0.0001), and hospital admissions of 14% (95% CI = 1.09-1.20; p < 0.0001); and (c) 69% increased mortality hazard (95% CI = 1.30-2.18; p < 0.0001) in parents younger than 50 years with no comorbidities, albeit small in absolute numbers.

CONCLUSION

Pediatric chronic diseases were negatively associated with parental employment, mental health, and mortality, and increased health care utilization.

WHAT IS KNOWN

• Studies on the impact of pediatric chronic diseases on parental health are qualitative. • Knowledge is unavailable regarding the impact on parental work, health care utilization, and mortality.

WHAT IS NEW

• Among 13,769 parents with a chronically ill child and 138,606 control parents, parents with a chronically ill child had 37% increased antidepressant drug redemptions, and these parents <50 years without comorbidities had 69% increased mortality hazard. • Medical doctors should consider the parental health condition and societal challenges related to having child with a chronic disease.

Musculoskeletal diseases in Marfan syndrome: a nationwide registry study

Background

Marfan syndrome is associated with abnormalities in the musculoskeletal system including scoliosis, pectus deformities, protrusio acetabuli, and foot deformities. Over a life span, many patients with Marfan syndrome will need treatment; however, the musculoskeletal morbidity over a life span is not well described. The aim of the present study was to assess the overall burden of musculoskeletal disease in patients with Marfan syndrome.

Materials and methods

A registry-based, nationwide epidemiological study of patients with a Ghent II verified Marfan syndrome diagnosis from 1977 to 2014. Each patient was matched on age, and sex with up to 100 controls from the background population.

Results

We identified 407 patients with Marfan syndrome and 40,700 controls and compared their musculoskeletal diagnoses and surgical treatments using Cox proportional hazards ratio (HR). The risk of a registration of a musculoskeletal diagnosis in patients with Marfan syndrome was significantly increased compared to controls (HR: 1.94 (1.69–2.24). One out of six with Marfan syndrome was registered with scoliosis (HR: 36.7 (27.5–48.9). Scoliosis was more common in women with Marfan syndrome compared to men (HR: 4.30 (1.73–1.08)). One out of 11 were registered with a pectus deformity HR: 40.8 (28.1–59.3), and one out of six with a deformity of the foot. Primarily pes planus (HR: 26.0 (15.2–44.3). The proportion of patients with Marfan syndrome (94/407) that underwent musculoskeletal surgery was also significantly higher (HR: 1.76 (1.43–2.16)). The major areas of surgery were the spine, pectups correction, and surgery of the foot/ankle. Ten patients with Marfan syndrome had elective orthopedic surgery without being recognized and diagnosed with Marfan syndrome until later in life. None of these had scoliosis, pectus deformity or a foot deformity. Among patients with an aortic dissection, the age at dissection was 34.3 years in those with at least one major musculoskeletal abnormality. In patients without a major abnormality the age at dissection was 45.1 years (p < 0.01).

Conclusions

The extent of musculoskeletal disease is quite significant in Marfan syndrome, and many will need corrective surgery during their life span. Surgeons should be aware of undiagnosed patients with Marfan syndrome when treating patients with a Marfan syndrome like-phenotype.

Incidence and prevalence of rheumatoid arthritis in Denmark from 1998 to 2018: a nationwide register-based study

Objective: To investigate the incidence and prevalence of rheumatoid arthritis (RA) in the adult Danish population.Method: In this nationwide register-based cohort study, patients with incident RA between 1998 and the end of 2018 were identified using Danish administrative registries. The age- and sex-standardized incidence rate (IR), incidence proportion (IP), lifetime risk (LR), and point prevalence (PP) of RA were calculated. RA was defined as a first-time RA diagnosis registered in the Danish National Patient Registry combined with a redeemed prescription of a conventional synthetic disease-modifying anti-rheumatic drug in the following year. In addition, three different case definitions of RA were explored.Results: The overall age- and sex-standardized IR of RA from 1998 to 2018 was 35.5 [95% confidence interval (CI) 35.1-35.9] per 100 000 person-years while the IP was 35.2 (95% CI 34.8-35.5) per 100 000 individuals. The IR was two-fold higher for women than for men. The LR of RA ranged from 2.3% to 3.4% for women and from 1.1% to 1.5% for men, depending on the RA case definition used. The overall PP of RA was 0.6% (95% CI 0.5-0.6%) in 2018: 0.8% (95% CI 0.7-0.8%) for women and 0.3% (95% CI 0.3-0.4%) for men. The prevalence increased about 1.5-fold from 2000 to 2018.Conclusion: The IR and PP were approximately two-fold higher for women than for men. The prevalence of RA in Denmark increased significantly from 2000 to 2018. The RA case definition had more impact on the results than the choice of denominator.

Intake of marine n-3 polyunsaturated fatty acids and the risk of rheumatoid arthritis: protocol for a cohort study using data from the Danish Diet, Cancer and Health cohort and Danish health registers

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory joint disease with multifactorial aetiology. Smoking is a well-established lifestyle risk factor, but diet may also have an impact on the risk of RA. Intake of the major marine n-3 polyunsaturated fatty acids in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been hypothesised to lower the risk of RA due to their anti-inflammatory effects, although based on limited knowledge. Therefore, we aim to investigate the associations between dietary intake of EPA and DHA and the risk of incident RA.

METHODS AND ANALYSIS

A cohort study. The follow-up design will be based on data from the Danish Diet, Cancer and Health cohort, which was established between 1993 and 1997. The participants will be followed through record linkage using nationwide registers including the Danish Civil Registration System, the Danish National Patient Registry and the Danish National Prescription Registry using the unique Civil Personal Registration number. Time-to-event analyses will be conducted with RA as the outcome of interest. The participants will be followed from inclusion until date of RA diagnosis, death, emigration or end of follow-up. HRs with 95% CIs obtained using Cox proportional hazard regression models, with age as underlying time scale and adjustment for established and potential risk factors, will be used as measures of association.

ETHICS AND DISSEMINATION

The study has been approved by the Data Protection Committee of Northern Jutland, Denmark (2019-87) and the North Denmark Region Committee on Health Research Ethics (N-20190031). Study results will be disseminated through peer-reviewed journals and presentations at international conferences.

Agreement Between Self-Reported Information and Administrative Data on Comorbidities, Imaging and Treatment in Denmark - A Validation Study of 38,745 Patients with Knee or Hip Osteoarthritis

Purpose

To validate self-reported information obtained from patients with knee or hip osteoarthritis (OA) in primary care against administrative data from the three national Danish registries.

Patients and Methods

We compared the baseline and 12-month follow-up data from 38,745 patients with knee or hip OA participating in the Good Life with osteoArthritis in Denmark (GLA:D^®) program with registry-based data on joint surgeries, pain medication dispensing, radiographs, and hospital diagnoses. Agreement was calculated using Cohen's Kappa (k) and percentage agreement, both with 95% CI.

Results

There was a moderate agreement between self-report and registry-based data for previous knee surgery (k=0.58, 84.99%) and a substantial agreement for previous hip surgery (k=0.73, 97.05%). Agreement varied from 0.05 to 0.95 and 84.99% to 99.94% for different types of surgeries with lowest agreement for collateral ligament surgery (k=0.05, 99.82%) and highest agreement for joint replacement (k=0.95, 99.54% for knee; k=0.95, 99.48% for hip). There was a moderate agreement (k=0.41, 81.59%) for knee and a slight agreement (k=0.20, 64.79%) for hip radiographs. Agreement varied from 0.01 to 0.53 and 65.39% to 99.90% for pain medication with lowest agreement for topical NSAID (k=0.01, 95.00%) and highest agreement for opioids (k=0.53, 92.56%). For comorbidities, agreement varied from 0.14 to 0.90 and 78.07% to 98.91%, with lowest agreement for anemia or other blood disease (k=0.14, 97.63%) and highest agreement for diabetes (k=0.90, 98.73%).

Conclusion

As the most common types of pain medication used by patients with OA can be bought over-the-counter and as most OA patients are treated in primary care, which is often not covered by national registries, self-report of pain medication use and comorbidities is preferred but cannot be sufficiently validated against registry-based data. Future studies collecting self-reported information on joint surgery and pain medication from patients with OA should use a less detailed categorization to improve accuracy.

Birthweight, body size, and growth during childhood and risks of rheumatoid arthritis: a large Danish cohort study

Objectives: Adult obesity may be positively associated with risks of rheumatoid arthritis (RA), but associations with early life body size are unknown. We examined whether birthweight, childhood body mass index (BMI), height, and changes in BMI and height were associated with risks of adult RA.Method: A cohort of 346 602 children (171 127 girls) from the Copenhagen School Health Records Register, born in 1930-1996, with measured weights and heights from 7 to 13 years of age, were included. Information on RA, including serological status, came from national registers from 1977 to 2017. Cox regressions were performed.Results: During a median of 35.1 years of observation time per person, 4991 individuals (3565 women) were registered with RA. Among girls, per BMI z-score, risks of RA and seropositive RA increased by 4-9% and 6-10%, respectively. Girls with overweight had higher risks of RA than girls without overweight. Girls who became overweight by 13 years of age had increased risks of RA compared to girls without overweight at 7 or 13 years (hazard ratio = 1.40, 95% confidence interval 1.19-1.66). For boys, associations between BMI and RA (including seropositive RA) were not statistically significant. Height was not associated with RA (any type) in girls. Taller boys had higher risks of RA, especially seropositive RA. Birthweight was not associated with RA.Conclusions: Among women, childhood adiposity was associated with increased risks of RA. Among men, childhood height was positively associated with risks of RA. These findings support the hypothesis that early life factors may be important in the aetiology of RA.

Association of Rheumatoid Arthritis in Pregnancy With School Performance of Offspring: A Danish Nationwide Register-Based Study

OBJECTIVE

To examine the overall cognitive development of children exposed to maternal rheumatoid arthritis (RA) in utero by comparing their school test scores to those of their peers.

METHODS

Children born in Denmark during 1995-2008 and listed in the National School Test Register were included (n = 738,862). Children exposed to maternal RA were identified through linkage of national registers. In separate analyses, exposure was subdivided according to maternal serostatus. Preclinical maternal RA was included as a separate exposure. The Danish national school tests are mandatory standardized tests. Results from all reading tests (grades 2, 4, 6, and 8) and mathematics tests (grades 3 and 6) from 2010-2017 were included. Test scores were compared according to maternal RA exposure for each test separately using linear regressions.

RESULTS

We identified 934 children exposed to maternal RA in utero. There were no differences in reading test scores between maternal RA exposed and unexposed children. RA exposed children scored poorer in both mathematics tests (adjusted differences of mean score -0.14 SD (95% confidence interval [95% CI] -0.23, -0.06) and -0.16 SD (95% CI -0.26, -0.07). There was no appreciable difference between children by maternal RA serostatus. Children exposed to preclinical RA (n = 589) showed the same pattern of performance as children exposed to RA.

CONCLUSION

RA-exposed children scored slightly poorer in mathematics tests but performed as well as their unexposed peers in the reading tests. The results do not suggest that RA in pregnancy has a major impact on offspring school performance.

Rheumatoid arthritis and risk of spontaneous abortion: a Danish nationwide cohort study

OBJECTIVES

To investigate the influence of RA or preclinical RA on the risk of spontaneous abortion (SA) while taking age and duration of RA into consideration.

METHODS

By linkage of data from Danish national registries, we established a nationwide cohort of pregnancies in Denmark from 1 January 1977 to 31 December 2014. We used multiple logistic regression to estimate; odds ratios (OR) for SA in women with RA or preclinical RA, compared with women without, and OR for SA by maternal age in women with RA or preclinical RA.

RESULTS

A total of 2 612 529 pregnancies were included. Women aged <35 years diagnosed with RA <5 years before pregnancy had an increased risk of SA (OR = 1.25 95% CI: 1.07, 1.48), compared with women without RA aged <35. Women at the same age diagnosed with RA ≥5 years before pregnancy had an OR of 1.14 (0.96-1.34), compared with women without. Among women with RA aged ≥35 years and women with preclinical RA at time of pregnancy, no increased risk of SA was found. The risk of SA increased by maternal age in both women with RA, preclinical RA and in women without.

CONCLUSION

Among women aged <35 years, the risk of SA was higher in women with RA compared with women without. After the age of 35 years, the risk of SA was no different from that among women without RA, even though the risk of SA increased with increasing age.

School performance, psychiatric comorbidity, and healthcare utilization in pediatric multiple sclerosis: A nationwide population-based observational study

Background:

Pediatric multiple sclerosis (MS) may hamper educational achievements due to psychiatric comorbidity and cognitive impairment. Our aims were to investigate school performance, psychiatric comorbidity, and healthcare utilization following pediatric MS and to differentiate between disability in MS and that arising from a non-brain-related chronic disease.

Methods:

We included all children (<18 years) with MS onset during 2008–2015 in Denmark with a medical record–validated MS diagnosis. The control groups were children from the general population or children with non-brain-related chronic diseases. Outcomes were register-based on 9–12 grade point average, psychiatric comorbidity, and healthcare visits.

Results:

Cohorts were children with MS ( n = 92), control children matched to children with MS ( n = 920), children with non-brain-related chronic diseases ( n = 9108), and “healthy” children with neither MS nor brain-related chronic disease ( n = 811,464). School performance in grades 9–12 was similar, but children with MS compared to those with non-brain-related chronic disease had an almost doubled hazard for psychiatric comorbidity (hazard ratio = 1.87; 95% confidence interval = 1.38–2.53; p < 0.0001) and a higher rate of all hospital visits ( p < 0.0001) but a lower rate of hospital admissions ( p = 0.001).

Conclusion:

Children with MS have a seemingly standard school performance but increased psychiatric comorbidity and a high rate of healthcare utilization.

Impact of rheumatoid arthritis on major cardiovascular events in patients with and without coronary artery disease

INTRODUCTION

Rheumatoid arthritis (RA) is a risk factor for cardiovascular disease. The clinical consequences of coincident RA and coronary artery disease (CAD) are unknown.

OBJECTIVE

We aimed to estimate the impact of RA on the risk of adverse cardiovascular events in patients with and without CAD.

METHODS

A population-based cohort of patients registered in the Western Denmark Heart Registry, who underwent coronary angiography (CAG) between 2003 and 2016, was stratified according to the presence of RA and CAD. Endpoints were myocardial infarction (MI), major adverse cardiovascular events (MACE; MI, ischaemic stroke and cardiac death) and all-cause mortality.

RESULTS

A total of 125 331 patients were included (RA: n=1732). Median follow-up was 5.2 years. Using patients with neither RA nor CAD as reference (cumulative MI incidence 2.7%), the 10-year risk of MI was increased for patients with RA alone (3.8%; adjusted incidence rate ratio (IRR_adj) 1.63, 95% CI 1.04 to 2.54), for patients with CAD alone (9.9%; IRR_adj 3.35, 95% CI 3.10 to 3.62), and highest for patients with both RA and CAD (12.2%; IRR_adj 4.53, 95% CI 3.66 to 5.59). Similar associations were observed for MACE an all-cause mortality.

CONCLUSIONS

In patients undergoing CAG, RA is significantly associated with the 10-year risk of MI, MACE and all-cause mortality regardless of the presence of CAD. However, patients with RA and CAD carry the largest risk, while the additive risk of RA in patients without CAD is minor. Among patients with RA, risk stratification by presence or absence of documented CAD may allow for screening and personalised treatment strategies.

Validity of Algorithms for Identification of Individuals Suffering from Chronic Noncancer Pain in Administrative Databases: A Systematic Review

BACKGROUND

Secondary analysis of health administrative databases is indispensable to enriching our understanding of health trajectories, health care utilization, and real-world risks and benefits of drugs among large populations.

OBJECTIVES

This systematic review aimed at assessing evidence about the validity of algorithms for the identification of individuals suffering from nonarthritic chronic noncancer pain (CNCP) in administrative databases.

METHODS

Studies reporting measures of diagnostic accuracy of such algorithms and published in English or French were searched in the Medline, Embase, CINAHL, AgeLine, PsycINFO, and Abstracts in Social Gerontology electronic databases without any dates of coverage restrictions up to March 1, 2018. Reference lists of included studies were also screened for additional publications.

RESULTS

Only six studies focused on commonly studied CNCP conditions and were included in the review. Some algorithms showed a ≥60% combination of sensitivity and specificity values (back pain disorders in general, fibromyalgia, low back pain, migraine, neck/back problems studied together). Only algorithms designed to identify fibromyalgia cases reached a ≥80% combination (without replication of findings in other studies/databases).

CONCLUSIONS

In summary, the present investigation informs us about the limited amount of literature available to guide and support the use of administrative databases as valid sources of data for research on CNCP. Considering the added value of such data sources, the important research gaps identified in this innovative review provide important directions for future research. The review protocol was registered with PROSPERO (CRD42018086402).

Positive Predictive Value of the Giant Cell Arteritis Diagnosis in the Danish National Patient Registry: A Validation Study

Purpose

To investigate the positive predictive value (PPV) of the giant cell arteritis (GCA) diagnosis in the Danish National Patient Registry (DNPR).

Patients and Methods

A total of 293 patients aged ≥50 years with a first-time diagnosis of GCA in the DNPR between January 2012 and December 2017 were included. Patients were sampled from two secondary and one tertiary care hospitals in the Central Region Denmark. Two independent investigators (PH & PT) reviewed all medical files, including medical records, treatment, biochemistry, histopathology and imaging, and either confirmed or dismissed the diagnosis of GCA. In case of disagreement, a consensus agreement was reached. Sub-analyses including number of redeemed prescriptions performed temporal artery biopsies (TABs), and number of GCA-related hospital contacts were performed.

Results

We confirmed the diagnosis of GCA in 183/293 patients resulting in a PPV of 62% (95% CI: 57–68). In patients with ≥3 redeemed prescriptions of glucocorticoids (GCs), we confirmed the diagnosis in 166/214 resulting in a PPV of 78% (95% CI: 71–83). In patients with ≥3 redeemed prescriptions of GCs and ≥3 GCA-related hospital contacts, we confirmed the diagnosis in 88/95 resulting in a PPV of 93% (95% CI: 85–96); however, this only included 88/183 confirmed GCA patients.

Conclusion

This is the first study to validate the diagnostic code of GCA in the DNPR. The overall PPV of GCA in the DNPR was 62%. Requiring redeemed prescriptions of GCs and/or GCA-related hospital contacts increase the PPV, but also excludes a significant number of GCA patients.

Rheumatoid Arthritis as a Risk Factor for Coronary Artery Calcification and Obstructive Coronary Artery Disease in Patients with Chest Pain: A Registry Based Cross-Sectional Study

Purpose

To examine the occurrence and severity of coronary artery disease (CAD) in patients with rheumatoid arthritis (RA) compared to non-RA patients in a population referred for coronary computed tomography angiography (CTA) due to chest pain.

Patients and Methods

In this cross-sectional study, 46,210 patients from a national CTA database were included. Patients with RA were stratified on serology, treatment with conventional synthetic or biological disease-modifying antirheumatic drugs (DMARDs), and the need for relapse or flare treatment with intraarticular or -muscular glucocorticoid injections (GCIs). Primary outcomes were coronary artery calcium score (CACS) >0 and CACS ≥400, and secondary outcome was obstructive CAD. Associations between RA and outcomes were examined using logistic regression and results were adjusted for age, sex, cardiovascular risk factors and comorbidities.

Results

A total of 395 (0.9%) RA patients were identified. In overall RA, crude odds ratio (OR) for having CACS >0 was 1.48 (1.21–1.82) and 1.52 (1.15–2.01) for CACS ≥400, whereas adjusted ORs were 1.08 (0.86–1.36) and 1.21 (0.89–1.65), respectively. Seropositive RA patients had adjusted OR of 1.16 (0.89–1.50) for CACS >0 and 1.37 (0.98–1.90) for CACS ≥400. Patients who had received ≥1 GCI in the period of 3 years prior to the CTA had an adjusted OR of 1.37 (0.94–2.00) for having CACS >0 and 1.46 (0.92–2.31) for CACS ≥400.

Conclusion

This is the first large-scale, CTA-based study examining the occurrence and severity of CAD in RA patients with symptoms suggestive of cardiovascular disease. A higher prevalence of coronary artery calcification was found in RA patients. After adjusting for age, sex, cardiovascular risk factors and comorbidities, the tendency was less pronounced. We found a trend for increased coronary calcification in RA patients being seropositive or needing treatment with GCI for a relapse or flare.

​Risk of major adverse cardiovascular events among patients with rheumatoid arthritis after initial CT-based diagnosis and treatment

OBJECTIVE

Rheumatoid arthritis (RA) is a known risk factor for developing coronary artery disease (CAD). The influence of RA on the prognosis after initial CAD diagnosis and treatment is however largely unknown. We examined the risk of major cardiovascular events among RA and non-RA patients with chest pain referred to cardiac CT.

METHODS

This was a follow-up study, using data from the Western Denmark Heart Registry, containing data on CT angiography examinations (Cardiac CT). Information on RA diagnosis and covariates were identified through nationwide administrative registers. The primary outcome was a combined outcome including, myocardial infarction, ischaemic or unspecified stroke, coronary artery bypass grafting, percutaneous coronary intervention, and all-cause mortality. Median time until events or censoring was 3.5 years (min/max: 0.0: 9.2). Cox proportional hazard models were used to examine the association between RA/non-RA patients and outcomes.

RESULTS

Among 42 257 patients, referred between 2008 and 2016, we identified 358 (0.8%) with RA. An increased risk was seen in RA compared with non-RA (adjusted HR 1.35, 95% CI 0.93 to 1.96). Among patients who had received flare treatment more than once prior to cardiac CT the adjusted HR 1.80 (95% CI 1.08 to 3.00), and among patients with seropositive RA the adjusted HR 1.42 (95% CI 0.93 to 2.16).

CONCLUSION

In patients referred to cardiac CT due to chest pain, we found a trend of an association between RA and the combined primary outcome, supporting that RA per se, but in particular seropositive and active RA, may increase the risk of CAD even after initial CAD diagnosis and treatment.

Improving accuracy of self-reported diagnoses of rheumatoid arthritis in the French prospective E3N-EPIC cohort: a validation study

OBJECTIVES

The French E3N-EPIC (Etude Epidémiologique auprès des femmes de la Mutuelle générale de l'Education Nationale-European Prospective Investigation into Cancer and Nutrition) cohort enrolled 98 995 women aged 40 to 65 years at inclusion since 1990 to study the main risk factors for cancer and severe chronic conditions in women. They were prospectively followed with biennially self-administered questionnaires collecting self-reported medical, environmental and lifestyle data. Our objective was to assess the accuracy of self-reported diagnoses of rheumatoid arthritis (RA) and to devise algorithms to improve the ascertainment of RA cases in our cohort.

DESIGN

A validation study.

PARTICIPANTS

Women who self-reported an inflammatory rheumatic disease (IRD) were asked to provide access to their medical record, and to answer an IRD questionnaire. Medical records were independently reviewed.

PRIMARY AND SECONDARY OUTCOME MEASURES

Positive predictive values (PPV) of self-reported RA alone, then coupled with the IRD questionnaire, and with a medication reimbursement database were assessed. These algorithms were then applied to the whole cohort to ascertain RA cases.

RESULTS

Of the 98 995 participants, 2692 self-reported RA. Medical records were available for a sample of 399 participants, including 305 who self-reported RA. Self-reported RA was accurate only for 42% participants. Combining self-reported diagnoses to answers to a specific IRD questionnaire or to the medication reimbursement database improved the PPV (75.6% and 90.1%, respectively). Using the devised algorithms, we could identify 964 RA cases in our cohort.

CONCLUSION

Accuracy of self-reported RA is poor but adding answers to a specific questionnaire or data from a medication reimbursement database performed satisfactorily to identify RA cases in our cohort. It will subsequently allow investigating many potential risk factors of RA in women.

Factors influencing harmonized health data collection, sharing and linkage in Denmark and Switzerland: A systematic review

INTRODUCTION

The digitalization of medicine has led to a considerable growth of heterogeneous health datasets, which could improve healthcare research if integrated into the clinical life cycle. This process requires, amongst other things, the harmonization of these datasets, which is a prerequisite to improve their quality, re-usability and interoperability. However, there is a wide range of factors that either hinder or favor the harmonized collection, sharing and linkage of health data.

OBJECTIVE

This systematic review aims to identify barriers and facilitators to health data harmonization-including data sharing and linkage-by a comparative analysis of studies from Denmark and Switzerland.

METHODS

Publications from PubMed, Web of Science, EMBASE and CINAHL involving cross-institutional or cross-border collection, sharing or linkage of health data from Denmark or Switzerland were searched to identify the reported barriers and facilitators to data harmonization.

RESULTS

Of the 345 projects included, 240 were single-country and 105 were multinational studies. Regarding national projects, a Swiss study reported on average more barriers and facilitators than a Danish study. Barriers and facilitators of a technical nature were most frequently reported.

CONCLUSION

This systematic review gathered evidence from Denmark and Switzerland on barriers and facilitators concerning data harmonization, sharing and linkage. Barriers and facilitators were strictly interrelated with the national context where projects were carried out. Structural changes, such as legislation implemented at the national level, were mirrored in the projects. This underlines the impact of national strategies in the field of health data. Our findings also suggest that more openness and clarity in the reporting of both barriers and facilitators to data harmonization constitute a key element to promote the successful management of new projects using health data and the implementation of proper policies in this field. Our study findings are thus meaningful beyond these two countries.

Body Fat Percentage, Waist Circumference, and Obesity As Risk Factors for Rheumatoid Arthritis: A Danish Cohort Study

OBJECTIVE

To investigate the relationship between bioimpedance-derived total body fat percentage, waist circumference, and body mass index (BMI) and the subsequent development of rheumatoid arthritis (RA).

METHODS

A population-based prospective cohort study was conducted using 55,037 patients enrolled in the Danish Diet, Cancer, and Health cohort. Baseline data included anthropometric measures and lifestyle factors. Individuals who developed RA were identified through linkage with the Danish National Patient Registry. The relationships between bioimpedance-derived body fat percentage, waist circumference, and BMI and incident RA were assessed using Cox proportional hazards regression models, stratifying by sex. All analyses were performed for overall RA and the serologic subtypes seropositive and other RA.

RESULTS

A total of 210 men (37.6% with seropositive RA) and 456 women (41.0% with seropositive RA) developed RA during a median follow-up of 20.1 years. In women, the overall RA risk was 10% higher for each 5% increment of total body fat (hazard ratio [HR] 1.10 [95% confidence interval (95% CI) 1.02-1.18]), 5% higher for each 5-cm increment of waist circumference (HR 1.05 [95% CI 1.01-1.10]), and nearly 50% higher in those whose BMI was in the obese range compared to normal range BMI (HR 1.46 [95% CI 1.12-1.90]). These positive associations were also found for patients with other RA. In men, there were no clear associations between body fat percentage, waist circumference, or BMI and RA. No significant associations were found for seropositive RA in women or men, possibly related to low sample size.

CONCLUSION

In women, higher body fat percentage, higher waist circumference, and obesity were associated with a higher risk of RA.