Rheumatoid arthritis and spondyloarthritis prevalence in four European countries - a comparative study

Introduction/Objective The objective was to compare rheumatoid arthritis (RA), spondyloarthritis (SpA) and subtypes of SpA prevalence in four European countries. Methods A 33-items detection questionnaire, containing self-reported diagnosis, classification criteria for RA and SpA, personal and family history, was translated using cross-cultural adaptation and validated in France, Turkey, Lithuania and Serbia, where it was used on a population sample. Suspected cases were evaluated and confirmed by a rheumatologist. Prevalence estimates were age-and sex-standardized to European standard population. Results In total, 33,454 people older than 18 years were screened and 31,454 interviewed: France 14,671, Lithuania 6,558, Serbia 6,213, Turkey 4,012. Standardized RA prevalence varied from 0.29% (95% CI: 0.17-0.40) in France to 0.57% (0.31-0.84) in Turkey; this inequality was mostly caused by differences in women prevalence (from 0.42% in France to 1.02% in Turkey) SpA prevalence was similar in France (0.30%), Serbia (0.35%) and Turkey (0.37%), but in Lithuania it was 0.89%, which could be caused by geographic and genetic differences, as SpA prevalence was higher in North and East Europe, as well as the human leukocyte antigen B27 presence. SpA prevalence was equally presented by gender for France and Serbia. Regarding SpA subtypes, ankylosing spondylitis prevalence varied from 0.07-0.30% (Serbia-Lithuania), PsA 0.10-0.26% (France-Lithuania), reactive arthritis was 0.09-0.18% (Serbia-Lithuania). Previously non-diagnosed SpA cases were found in 6.9% in France, 25.9% in Lithuania and 31.2% in Serbia. Conclusion East-West decreasing tendency for the female RA prevalence was noted. SpA was higher in North-Eastern Europe than in its Western and Southern part. One quarter of the SpA patients in Lithuania and one third in Serbia were not previously diagnosed. The SpA population prevalence was higher than expected and similar to RA.