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Delayed timing of physical therapy initiation increases the risk of future opioid use in individuals with knee osteoarthritis: a real-world cohort study


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.

  • exercise
  • knee
  • cohort studies
  • rehabilitation

Data availability statement

Data may be obtained from a third party and are not publicly available. Data used for this study are owned by Optum Labs.

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