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.