Objective: We assessed whether late versus early initiation of physical therapy (PT) was related to greater risk of future opioid use in people with knee osteoarthritis (OA) who receive PT.
Methods: We used Commercial and Medicare Advantage claims data from 1999 to 2018 from American adults with incident knee OA referred for PT within 1 year of diagnosis. We categorised people as opioid naïve or opioid experienced based on prior prescriptions. We examined the association of timing of PT initiation with any and chronic opioid use over 1 year.
Results: Of the 67 245 individuals with incident knee OA, 35 899 were opioid naïve and 31 346 were opioid experienced. In the opioid naïve group, compared with PT within 1 month, PT 1 to <3, 3 to <6, 6 to <9, 9-12 months from diagnosis was associated with adjusted risk ratio (aRR (95% CIs)) for any opioid use of 1.18 (1.10 to 1.28), 1.49 (1.37 to 1.61), 1.73 (1.58 to 1.89) and 1.93 (1.76 to 2.12), respectively; aRRs (95% CIs) for chronic opioid use were 1.25 (1.01 to 1.54), 1.83 (1.48 to 2.26), 2.29 (1.82 to 2.89) and 2.50 (1.96 to 3.19). Results were similar among opioid experienced; aRRs (95% CIs) for any opioid use were 1.19 (1.14 to 1.24), 1.32 (1.26 to 1.37), 1.39 (1.32 to 1.45) and 1.54 (1.46 to 1.61); aRRs (95% CIs) for chronic opioid use were 1.25 (1.17 to1.34), 1.43 (1.33 to 1.54), 1.53 (1.41 to 1.66) and 1.65 (1.51 to 1.80).
Conclusion: Compared with PT initiation within 1 month, delayed PT initiation was associated with higher risk of opioid use in people with incident knee OA. The longer the delay in PT initiation, the greater was the risk.
Keywords: cohort studies; exercise; knee; rehabilitation.
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