Prevalence and incidence of rheumatoid arthritis in southern Sweden 2008 and their relation to prescribed biologics

Abstract

Objectives: To gain updated estimates of prevalence and incidence of RA and proportion on biological treatment in southern Sweden.

Methods: Inpatient and outpatient health care provided to residents in the southernmost county of Sweden (1.2 million inhabitants) is registered in the Skåne Health Care Register (SHCR). We identified residents aged > or = 20 years who had received a diagnosis of RA at least twice during 2003-08. Valid point prevalence estimates by 31 December 2008 were obtained by linkage to the Swedish population register, and information on biological treatment was obtained from the South Swedish Arthritis Treatment Group register. We also tested our estimates of RA occurrence in a series of sensitivity analyses to investigate the effect of altered case criteria and the uncertainty generated by clinical visits without diagnoses.

Results: The prevalence of RA in adults was estimated to 0.66% (women = 0.94%, men = 0.37%). The prevalence peaked at age 70-79 years (women = 2.1%, men = 1.1%) before dropping in those aged > or = 80 years. Of prevalent cases, 20% had ongoing biological treatment, a percentage that was highest in women aged 40-49 years (36%). The incidence of RA in 2008 was estimated as 50/100,000 (women = 68/100,000, men = 32/100,000).

Conclusions: When compared with a previous report from southern Sweden, the prevalence of RA seems not to have declined in the last decade. The proportion of patients with ongoing biological treatment was slightly higher in women than men. SHCR data are promising additions to other methods to gain frequency estimates of clinically important disease in a timely and cost-efficient manner.