A community-based study on the prevalence of spondyloarthritis and inflammatory back pain in Mexicans.

BACKGROUND The prevalence of spondyloarthritis (SpA) varies across populations. In Mexicans, the prevalence of SpA is still unknown. OBJECTIVE The objective of this study was to determine the prevalence of SpA in the community as well as that of inflammatory back pain (IBP) and ankylosing spondylitis (AS). METHODS We identified individuals older than 18 years with nontraumatic back pain (BP) in a door-to-door nurse survey using the Community Oriented Program for the Control of Rheumatic Diseases. Then, general physicians and rheumatology fellows selected those likely to have IBP (Berlin criteria). Finally, 2 expert rheumatologists assessed IBP individuals according to clinical data and classification criteria and requested HLA-B27 and radiographic studies to determine the clinical condition of the individual and SpA (European SpA Study Group) classification. RESULTS The prevalence of BP among 4059 individuals was 14.6% (95% confidence interval [CI], 13.6-15.8). The prevalence of IBP and SpA was 1.3% (95% CI, 1.0-1.7) and 0.6% (95% CI, 0.4-0.9), respectively. Ankylosing spondylitis prevalence was 0.1% (95% CI, 0.02-0.2). Inflammatory back pain and SpA percentage of males and females was similar. The percentage of individuals with IBP according to the 2 experts was lower than that determined by general physicians and rheumatology fellows, but all cases with HLA-B27, radiographic sacroiliitis, SpA, and AS had previous IBP confirmation by the expert. CONCLUSIONS The prevalence and sex distribution of patients classified with SpA in this community study--as well as that of patients diagnosed with AS--are consistent with those found in recent studies. Expert assessment of individuals with positive responses to questionnaires is relevant for the classification of IBP and SpA.