Systemic lupus erythematosus in the Arctic region of Norway.J Rheumatol 2001; 28(3):539-46JR
The marked regional variation in the incidence, prevalence, and presentation of systemic lupus erythematosus (SLE) is possibly related to differing spectra of local environmental factors. The aim of this study was to describe such features in a homogenous Caucasian population exposed to an Arctic climate.
The study area consisted of the 2 northernmost counties of Norway (middle population 222,403) where 4 hospitals (containing only one rheumatology service) provide specialized health care. Retrieval sources were (1) hospital inpatient discharge registries; (2) hospital outpatient registries; (3) mortality database of the National Office for Statistics. Databases were searched with codes for SLE, S ogren's syndrome, unclassified connective tissue disease, and discoid lupus for the period 1978-96. Only patients meeting 1982 American College of Rheumatology criteria for SLE were included in the analysis. Annual incidence rate (AIR), point prevalence (PP), and mortality rates were estimated per 100,000 at risk.
Eighty-three incident cases of adult SLE (87% female, mean age 40.6 yrs at diagnosis) were encountered. Crude AIR of SLE in the whole study period was 2.6 (95% CI 1.9-2.9) for adults. Sex-specific AIR was 4.6 for adult women and 0.6 for adult men. AIR in the first (2.4) and second 9-year period (2.7) was similar (p > 0.2). The crude overall PP for SLE at January 1, 1996, was 44.9 and was highest in women aged 3149 (PP 102.5). Mortality in incident cases was 9.6% (after a mean followup of 99 mo) with overall 10-year survival estimated at 75%.
In a Caucasian population exposed to the Arctic climate incidence of SLE is rather low and stable. Course and presentation of SLE in the Arctic is not different from similar populations in the Western world. Improved outcome now makes SLE a disease present in 1 per 1,000 Norwegian women aged > 30 years.