Abstract
Objective Both frailty and osteoarthritis become common with aging. Given their shared age-related incidence, we hypothesized that greater baseline frailty, measured by frailty index, would be associated with worse osteoarthritis outcomes, including higher incidence, poorer Knee Injury and Osteoarthritis Outcome Score (KOOS) trajectories, increased fall risk, and higher rates of total or partial knee (KA) or hip (HA) arthroplasty in middle-aged and older adults.
Methods A frailty index score was calculated for 4753 participants (58.53% females; mean age 61.2, 95% CI: 60.94-61.46) from the Osteoarthritis Initiative (OAI) broken into control, incidence, and progression groups. Longitudinal OAI outcomes including incidence, KOOS progression, falls, and KA/HA were extracted for ~9 years from baseline.
Results Higher baseline frailty was associated with development of osteoarthritis by three-, five- and nine-year follow-up (all, p<0.001) with greatest impact at nine years (OR: 1.73, 95% CI: 1.52-1.97, p<0.001). Disease trajectory, as measured by KOOS subscale scores, was negatively influenced by increasing frailty (all, p<0.001), the greatest impact being on KOOS Function (Estimate: -9.52, 95% CI: -10.28 to -8.77, p<0.001). A 0.1 difference in baseline frailty index scores was associated with increase in the odds of experiencing a fall within 3-years of baseline (OR: 1.44, 95% CI: 1.32-1.58, p<0.001). Regardless of surgical site, frailty index scores did not significantly impact risk of experiencing KA/HA except in females undergoing HA (HR: 1.29, 95% CI: 1.04-1.61, p=0.02).
Conclusion Frailty was associated with greater risk of osteoarthritis incidence and falls, as well as KOOS-measured disease progression, but not joint-replacement surgery-free time.
