Prevalence of spondyloarthritis and its subtypes - are they really comparable?

Abstract

Introduction/Objective. Increasing spondyloarthritis (SpA) prevalence in the last several decades cannot be attributed to disease manifestations alone. The objective of this paper is to review the prevalence of SpA and its subtypes: ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis (ReA), SpA related to inflammatory bowel disease (IBD) and undifferentiated SpA (UnSpA). Methods. MEDLINE literature search was done via PubMed, Google Scholar, and Embase databases, using terms for spondyloarthritis, and prevalence, with an additional hand searching. Results. As compared with southern European countries, northern European countries (Scotland, Sweden, France) showed lower SpA prevalence rates (0.21?0.45% vs. 1.06% and 1.35% in Italy and Turkey, respectively). The lowest world SpA prevalence was in African and Southeast Asian countries (0?0.19%), and the highest was in Alaska (2.5%). The widest variability in PsA prevalence was in Europe (northern 0.02?0.19%, southern 0.42%). The lowest world PsA prevalence was in Japan (0.001%), followed by China (0.01?0.10%). The European ReA prevalence ranged from 0.04% in Greece to 0.10% in Serbia and Germany, and the European UnSpA prevalence varied from 0.02% in Serbia to 0.67% in Germany; the highest world UnSpA prevalence was in Lebanon (3.4%). Studies aimed at estimating the SpA prevalence differed in sampling strategy and confirmation criteria, different cutoffs for age groups inclusion, presentation of standardized or row results, etc. Conclusion. Variation in the SpA prevalence cannot be attributed to genetic or geographic distribution only. Differences in methodology of studies add to the diversification, described more in-depth in this review.