Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Geographical Variation of Rheumatoid Arthritis in Stockholm County, Sweden.

Kallberg4,  Henrik, Vieira2,  Veronica M., Hart1,  Jamie E., Costenbader3,  Karen H., Holmqvist5,  Marie, Klareskog6,  Lars, Alfredsson5,  Lars

Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston Massachusetts, Department of Epidemiology, Harvard School of Public Health, Boston Massachusetts
Department of Environmental Health, Boston University School of Public Health, Boston, MA
Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital and Harvard Medical School, Boston Massachusetts
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
Rheumatology Unit, Department of Medicine, Karolinska Institutet/Karolinska Hospital, Stockholm, Sweden

Background:

Past studies have displayed geographical variation in RA incidence, suggesting the influence of environmental factors on RA etiology. We aimed to investigate geographical distribution of risk of developing RA within Stockholm County, Sweden.

Methods:

We studied spatial variation in incident RA among 1095 incident cases and 1251 controls participating in a Swedish case-control study. The Swedish RA study is a population-based case-control study that has collected information from almost all newly diagnosed RA cases in Stockholm County. Analyses were limited to those subjects living in Stockholm County prior to RA diagnosis for cases and prior to matched date for controls and having geocoded addresses. We used Generalized Additive Models (GAM) to create a risk surface, calculate odds ratios and adjust for potential confounding by smoking and socioeconomic status defined through occupation held at the time of diagnosis. We performed a stratified analysis based on presence/absence of antibodies to citrullinated peptides (ACPA).

Results:

We found significant spatial variation regarding risk of developing RA in adjusted models (p < 0.05, Figure 1.). The spatial variation decreased for some areas but remained significant after adjusting for potential confounding from smoking and socioeconomic status. The stratified analysis for ACPA positive RA cases (n = 700) showed similar results as for the non-stratified analysis. We did not manage to estimate valid odds ratios for the RA subgroup without ACPA because of few cases (n = 395) in that subgroup.

Figure 1. Spatial variation regarding odds ratios of developing RA in Stockholm County. Yellow-Red indicate areas (Dotted squares) associated with increased odds ratios for RA and Blue indicate areas (Dotted circles) with associated with decreased risks of developing RA.

Conclusions:

Our analysis indicates that there is geographical variation within Stockholm County regarding risk of developing RA. This variation is not explained by smoking or current socioeconomic status according to occupational status. Therefore we suggest further studies in order to investigate potential sociodemographic or environmental factors to explain this variation.

To cite this abstract, please use the following information:
Kallberg, Henrik, Vieira, Veronica M., Hart, Jamie E., Costenbader, Karen H., Holmqvist, Marie, Klareskog, Lars, et al; Geographical Variation of Rheumatoid Arthritis in Stockholm County, Sweden. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :64
DOI: 10.1002/art.27833

Abstract Supplement

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