Abstract
This study examined the association of single and multiple-site osteoarthritis (OA) at baseline with physical and mental health-related quality of life (HRQOL) over an 8-year follow-up period in the US adults compared to those at high risk of knee OA. This study is a prospective longitudinal design over 8 years of follow-up. Data from 4796 participants aged between 45 and 79 years were acquired from the osteoarthritis initiative. Based on self-reported physician-diagnosed OA and grade ≥ 2 in either knee using Kellgren and Lawrence grade at baseline, participants were categorized into high risk of knee OA (n = 1560), 1-site OA (n = 1233), 2-site OA (n = 1272), and ≥ 3-site OA (n = 721) groups. Physical and mental components of HRQOL were assessed over an 8-year follow-up period using the 12-item Short Form Health Survey. Two separate generalized estimating equations were used. A total of 4786 participants were included in the final model. Results from the generalized estimating equation showed that participants with 1-site OA (Beta [B] = -1.04, 95% confidence intervals [CI]: (-1.5, -.6), P < .001), 2-site OA (B = -2.17, 95% CI: (-2.6, -1.7), P < .001), and ≥ 3-site OA (B = -4.98, 95% CI: (-5.7, -4.3), P < .001) had significantly declined physical composite score of HRQOL over time than those without OA at baseline after adjustments for covariates, such as age, sex, race, educational status, body mass index, number of comorbidities, physical activity level, and depressive symptoms. Mental composite score of HRQOL had significantly increased across 2-site OA (B = 0.46, 95% CI: (.2,.7), P = .001), and ≥ 3-site OA (B = 0.86, 95% CI: (.5, 1.2), P < .001) after adjustments for covariates. US adults with single and multiple joint OA at baseline were associated with a decline in physical and an increase in mental HRQOL than those at higher risk of knee OA at baseline.