Psychological factors and their relation to osteoarthritis pain.

OBJECTIVE We assessed associations between mental health and osteoarthritis (OA) pain. METHODS Two hundred and sixty-six subjects with hip and/or knee OA from the Longitudinal Examination of Arthritis Pain (LEAP) study were interviewed weekly for 12 weeks, measuring Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain subscale and 5-item Mental Health Inventory (MHI-5). We examined associations between MHI-5 and its change, divided into quartiles, to WOMAC pain and its change (occurring 1 week later) using linear regression, adjusting for age, sex, body mass index (BMI), medication use. Generalized estimating equations were used to account for repeated measurements correlation. We also assessed the relation of MHI-5 to the risk of pain flare using conditional logistic regression in a case-crossover study. RESULTS Seventy-five men and 191 women were included. Mean age was 65.0, mean BMI 31.5. 82% had knee as their primary site. The mean WOMAC score was 2.93 in the quartile with the highest MHI-5 as compared with a mean WOMAC of 4.57 in the quartile with the lowest MHI-5 (P for trend across quartiles <0.001). In the case-crossover analysis (91 subjects), periods with the worst MHI-5 quartile had 2.1 times the odds of a pain flare the subsequent week as compared to periods with the best MHI-5 quartile (P<0.001). CONCLUSION We demonstrate an association between worsened measures of mental health and OA pain and risk of pain flares. General mental health is a modifiable component of health and may represent a new avenue for prevention of OA pain flares.