Abstract
OBJECTIVE: This study investigated trajectories of patient acceptable symptom state (PASS) among participants of digital education and exercise therapy for knee and hip osteoarthritis. METHODS: A longitudinal observational study among individuals aged at least 40 years who participated in the digital program. Participants completed PASS (yes/no) at enrollment and at least one follow-up during 1 year after enrollment (N = 15,253). Group-based trajectory modeling was used to identify groups with distinct PASS trajectories. We used multinomial logistic regression and linear random intercept models to explore predictors and compare changes in patient-reported outcome measures (PROMs) across trajectory subgroups. RESULTS: The proportion of participants reporting acceptable symptom state rose from 17.4% (95% confidence interval [CI] 16.8%-18.1%) at enrollment to 42.4% (95% CI 41.6%-43.1%) and 48.9% (95% CI 47.5%-50.2%) at 3- and 12-month follow-ups, respectively. We identified four PASS trajectories: (1) "persistently not achieving PASS" (PNAP) (45.1%), (2) "early sustained PASS" (ESP) (34.8%), (3) "gradually increasing satisfaction" (GIS) (10.8%), and (4) "early PASS, later unacceptable PASS" (9.3%). Among baseline variables, female sex, older age, nonmetropolitan residence, lower education, knee osteoarthritis, fear of movement, no walking difficulties, no wish for surgery, and better PROMs were generally associated with higher odds of following trajectories other than the PNAP. All trajectories experienced improvements in PROMs, with generally larger improvements in the ESP and GIS groups than the other two groups. CONCLUSION: The percentage of participants achieving PASS almost tripled at 12 months. Improvements in PROMs across all PASS trajectories highlights the importance of distinction between "feeling better" and "feeling good."