Level of participation in physical therapy or an internet-based exercise training program: associations with outcomes for patients with knee osteoarthritis

BACKGROUND: To examine whether number of physical therapy (PT) visits or amount of use of an internet-based exercise training (IBET) program is associated with differential improvement in outcomes for participants with knee osteoarthritis (OA). METHODS: A secondary analysis was performed using data from participants in 2 arms of a randomized control trial for individuals with symptomatic knee OA: PT (N = 135) or IBET (N = 124). We examined associations of number of PT visits attended (up to 8) or number of days the IBET website was accessed during the initial 4-month study period with changes in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total, pain and function subscales, as well as a 2-min Step Test, at 4-month and 12-month follow-up. RESULTS: Participants with more PT visits experienced greater improvement in WOMAC total score (estimate per additional visit = − 1.18, CI 95% = − 1.91, 0.46, p < 0.001) and function subscore (estimate = − 0.80, CI 95% = − 1.33, − 0.28, p < 0.001) across follow-up periods. For WOMAC pain subscale, the association with number of PT visits varied significantly between 4- and 12-month follow-up, with a stronger relationship at 4-months. There was a non-significant trend for more PT visits to be associated with greater improvement in 2-min Step Test. More frequent use of the IBET website was not associated with greater improvement for any outcome, at either time point. CONCLUSION: Increased number of PT visits was associated with improved outcomes, and some of this benefit persisted 8 months after PT ended. This provides guidance for PT clinical practice and policies. TRIAL REGISTRATION: NCT02312713, posted 9/25/2015.