Observational Study: Predictors of a Successful Functional Outcome in Persons Who Receive Physical Therapy for Knee Osteoarthritis.

A retrospective design was employed to determine what factors are predictive of achieving a successful outcome for individuals with knee osteoarthritis following an episode of physical therapy. Success was defined as achieving the minimum clinically important difference with the change in the lower extremity functional scale (LEFS). Receiving guideline adherent care was hypothesized to increase odds of success. Data for treatment interventions, health care utilization, patient characteristics, and LEFS scores were collected from electronic health records from 2014-2018 across 34 outpatient clinics. The sample (N = 706) was primarily female, White, and older adults. Receiving guideline adherent care did not predict odds of achieving success. Patient age, initial LEFS score, opioid prescription, number of visits, and Medicare/Medicaid insurance were predictive of the outcome. Increasing age after 65 years predicted decreased odds of success. Older adults showed improved odds with an opioid prescription and with increased number of visits from two through 18 therapy sessions. Opportunities exist for further health services research on optimal management of knee OA, including underutilization of physical therapy (only 6% in this study), measuring adherence to CPGs, determining recommended intensity for interventions, and the effects of non-physical therapy interventions such as opioid use on outcomes.