Risk factors for incident self-reported arthritis in a 20 year followup of the Alameda County Study Cohort.

Objective: This longitudinal study examined the following variables as possible risk factors for self-reported arthritis: age, sex, race, body mass index (BMI), depressive symptoms, leisure-time physical activity, cigarette use, alcohol, hypertension, diabetes mellitus, education, income, and hard physical work.

Methods: Altogether, 1149 women and 964 men from the Alameda County Study Cohort without self-reported arthritis in 1974 were assessed for incident self-reported arthritis in 1994.

Results: In a multivariate model, the following variables were associated with increased odds of incident arthritis: increasing age (age 45-49, odds ratio 2.00, 95% confidence interval 1.40-2.85; age 50+, OR 3.13, 95% CI 2.32-4.22), BMI for women only (4th quintile, OR 1.65, 95% CI 1.05-2.60; 5th quintile, OR 1.88, 95% CI 1.19-2.95), female sex (OR 1.48, 95% CI 1.20-1.83), and >/= 5 depressive symptoms (OR 1.53, 95% CI 1.12-2.10). Leisure-time physical activity in the highest quartile was protective (OR 0.69, 95% CI 0.51-0.95). All other factors were not associated with arthritis.

Conclusion: This study indicates that depressive symptoms, as well as age, sex, and BMI, are independent risk factors for arthritis. This is the first longitudinal population based study to examine and establish that prior depressive symptoms are a risk factor for arthritis.