Regional differences regarding risk of developing rheumatoid arthritis in Stockholm County, Sweden: results from the Swedish Epidemiological Investigation of Rheumatoid Arthritis (EIRA) study

The Geospatial Distribution of Myositis and Its Phenotypes in the United States and Associations With Roadways: Findings From a National Myositis Patient Registry

Background

Little is known about the spatial distribution of idiopathic inflammatory myopathies (IIM) in the United States (U.S.), or their geospatial associations.

Methods

We studied a national myositis patient registry, with cases diagnosed in the contiguous U.S. from 1985–2011 and comprised of dermatomyositis (DM, n = 484), polymyositis (PM, n = 358), and inclusion body myositis (IBM, n = 318) patients. To assess the association of myositis prevalence with distance from roads, we employed log-Gaussian Cox process models, offset with population density.

Results

The U.S. IIM case distribution demonstrated a higher concentration in the Northest. DM, IBM, and cases with lung disease were more common in the East, whereas PM cases were more common in the Southeast. One area in the West and one area in the South had a significant excess in cases of DM relative to PM and of cases with lung disease relative to those without lung disease, respectively. IIM cases tended to cluster, with between-points interactions more intense in the Northeast and less in the South. There was a trend of a higher prevalence of IIM and its major phenotypes among people living within 50 m of a roadway relative to living beyond 200 m. Demographic characteristics, rural-urban commuting area, and female percentage were significantly associated with the prevalence of IIM and with major phenotypes.

Conclusions

Using a large U.S. database to evaluate the spatial distribution of IIM and its phenotypes, this study suggests clustering in some regions of the U.S. and a possible association of proximity to roadways.

[Prevalence of rheumatoid arthritis in Germany based on health insurance data : Regional differences and first results of the PROCLAIR study]

BACKGROUND

Rheumatoid arthritis (RA) is the most common chronic inflammatory joint disease with a prevalence of up to 1 % in the adult population.

OBJECTIVE

This study describes the prevalence of RA diagnoses in outpatient health insurance claims data, based on different case definitions and stratified by age, sex and region of residence.

METHODS

Based on data from a nationwide statutory health insurance fund (BARMER GEK) from the year 2013, a cross-sectional study of insurants aged 18 years or older was conducted. The following case definitions were applied: A) a diagnosis of seropositive rheumatoid arthritis (M05) or other rheumatoid arthritis (M06) according to the international classification of diseases 10 German modification (ICD-10-GM) in at least two quarterly periods of the year 2013, B) case definition A plus determination of C‑reactive protein (CRP) or erythrocyte sedimentation rate (ESR) at least once, C) case definition B plus specific drug therapy and D) case definition A plus treatment by a rheumatologist. Raw as well as age and sex-standardized prevalences were calculated and stratified according to the federal state.

RESULTS

The study population consisted of 7,155,315 insurants of whom 60.2 % were female. Overall, RA prevalences for the respective case definitions were 1.62 % (A), 1.11 % (B), 0.94 % (C) and 0.64 % (D). When standardized to the German population the prevalences were 1.38 % (A), 0.95 % (B), 0.81 % (C) and 0.55 % (D). The proportion of women was approximately 80 % for all case definitions. Prevalences increased with age, peaking in the age group 70-79 years old and showing the highest values in eastern and the lowest in southern Germany for raw as well as standardized measures.

CONCLUSION

Regional differences in the prevalence of RA diagnoses in health insurance claims data were observed independent of age, sex and case definition. The expected prevalence according to the results of international studies was best achieved when case definitions with CRP or ESR were considered.

Prevalence of Periodontitis in Patients with Established Rheumatoid Arthritis: A Swedish Population Based Case-Control Study

Introduction

The possible hypothesis of a link between periodontitis and rheumatoid arthritis (RA), specifically anti-citrullinated protein antibody (ACPA) positive RA, prompted us to investigate the prevalence of periodontitis in the Swedish Epidemiological Investigation of RA (EIRA), a well-characterised population-based RA case-control cohort.

Methods

Periodontal status of 2,740 RA cases and 3,942 matched controls was retrieved through linking EIRA with the National Dental Health Registry (DHR), where dental diagnostic- and treatment codes on the adult Swedish population have been registered. Dental records from 100 cases and controls were reviewed to validate the periodontal diagnostic codes in DHR.

Results

The reviewed dental records confirmed 90% of the periodontitis diagnoses in DHR among RA cases, and 88% among controls. We found the positive predictive value of periodontitis diagnoses in the DHR to be 89% (95% CI 78 to 95%) with a sensitivity of 77% (95% CI: 65 to 86%). In total, 86% of EIRA participants were identified in DHR. The risk for periodontitis increased by age and current smoking status in both cases as well as controls. No significant differences in prevalence of periodontal disease in terms of gingivitis, periodontitis, peri-implantitis or increased risk for periodontitis or peri-implantitis were observed between RA cases and controls. In addition, there was no difference on the basis of seropositivity, ACPA or rheumatoid factor (RF), among patients with RA.

Conclusions

Our data verify that smoking and ageing are risk factors for periodontitis, both in RA and controls. We found no evidence of an increased prevalence of periodontitis in patients with established RA compared to healthy controls, and no differences based on ACPA or RF status among RA subjects.

Prediction of future rheumatoid arthritis

Rheumatoid arthritis (RA) results from an interaction between genetic susceptibility and environmental factors. Several of these factors are known, such as family history of RA, high birth weight, smoking, silica exposure, alcohol nonuse, obesity, diabetes mellitus, rheumatoid factor, anti-citrullinated protein antibody, and genetic variants such as the shared epitope and protein tyrosine phosphatase nonreceptor type 22. The impact of these factors can be modeled in the 2 main groups at risk of RA: family members of patients with RA and seropositive persons with or without arthralgia. Current models have the potential to select individuals for preventive strategies.