Arthritis diagnosis and symptoms are positively associated with specific physical job exposures in lower- and middle-income countries: Cross-sectional results from the World Health Organization's Study on global AGEing and adult health (SAGE)

Background: In higher income countries, work-related squatting and heavy lifting have been associated with increased arthritis risk. Here, we address the paucity of data regarding associations between arthritis and work-related physical stressors in lower- and middle-income countries. Methods: Data were extracted from the Study on global AGEing and adult health (SAGE) Wave 1 (2007-10) for adults (aged ≥50 years) from Ghana, India, Russia and South Africa for whom detailed occupation data was available (n = 21,389; 49.2% women). Arthritis cases were identified using a symptom-defined algorithm (current) and self-reported doctor-diagnosis (lifetime). A sex-specific Job Exposure Matrix was used to classify work-related stressors: heavy physical work, kneeling/squatting, heavy lifting, arm elevation and awkward trunk posture. Using the International Standard Classification of Occupations, we linked SAGE and the Job Exposure Matrix. Logistic regression was used to investigate associations between arthritis and work-related stressors, adjusting for age (10 year age groupings), potential socioeconomic-related confounders, and body mass index. Excess exposure risk due to two-way interactions with other risk factors were explored. Results: Doctor-diagnosed arthritis was associated with heavy physical work (adjusted odds ratios [OR] 1.12, 95%CI 1.01-1.23), awkward trunk posture (adjusted OR 1.23, 95%CI 1.12-1.36), kneeling or squatting (adjusted OR 1.25, 95%CI 1.12-1.38), and arm elevation (adjusted OR 1.66, 95%CI 1.37-2.00). Symptom-based arthritis was associated with kneeling or squatting (adjusted OR 1.27, 95%CI 1.08-1.50), heavy lifting (adjusted OR 1.33, 95%CI 1.11-1.58), and arm elevation (adjusted OR 2.16, 95%CI 1.63-2.86). Two-way interactions suggested excess arthritis risk existed for higher body mass index, and higher income or education. Conclusions: Minimization of occupational health risk factors is common practice in higher income countries: attention should now be directed toward reducing work-related arthritis burden in lower- and middle-income countries.