Epidemiology of rheumatic diseases. A community-based study in urban and rural populations in the state of Nuevo Leon, Mexico.

OBJECTIVE To estimate the prevalence of rheumatic diseases in rural and urban populations using the WHO-ILAR COPCORD questionnaire. METHODS We conducted a cross-sectional home survey in subjects > 18 years of age in the Mexican state of Nuevo Leon. Results were validated locally against physical examination in positive cases according to an operational definition by 2 rheumatologists. We used a random, balanced, and stratified sample by region of representative subjects. RESULTS We surveyed 4713 individuals with a mean age of 43.6 years (SD 17.3); 55.9% were women and 87.1% were from urban areas. Excluding trauma, 1278 individuals (27.1%, 95% CI 25.8%-28.4%) reported musculoskeletal pain in the last 7 days; the prevalence of this variable was almost twice as frequent in women (33% vs 17% in men); 529 (11.2%) had pain associated with trauma. The global prevalence of pain was 38.3%. Mean pain score was 2.4 (SD 3.4) on a pain scale of 0-10. Most subjects classified as positive according to case definition (99%) were evaluated by a rheumatologist. Main diagnoses were osteoarthritis in 17.3% (95% CI 16.2-18.4), back pain in 9.8% (95% CI 9.0-10.7), undifferentiated arthritis in 2.4% (95% CI 2.0-2.9), rheumatoid arthritis in 0.4% (95% CI 0.2-0.6), fibromyalgia in 0.8% (95% CI 0.6-1.1), and gout in 0.3% (95% CI 0.1-0.5). CONCLUSION This is the first regional COPCORD study in Mexico performed with a systematic sampling, showing a high prevalence of pain. COPCORD is a useful tool for the early detection of rheumatic diseases as well as for accurately referring patients to different medical care centers and to reduce underreporting of rheumatic diseases.