Prescription Opioids Higher Among Knee Arthroplasty Recipients Randomized to Inpatient Rehabilitation

Abstract

Objective: To determine whether the purchase of prescription opioids was lower among people randomized to inpatient rehabilitation (IR) compared with those discharged directly home following total knee arthroplasty (TKA). Method: A secondary analysis of a previous clinical trial in which participants were randomized 3 to 5 days after -surgery to 10 days of IR and a home program or to a home program alone. The primary outcome for this secondary analysis was the purchase of opioid-based pain relief up to 10-weeks after surgery, which was captured via patient diaries. Between-group differences were analyzed using a χ2 test and relative risk (RR) (95% confidence interval [CI]). We report this outcome alongside the main outcomes observed at 10 weeks for the original study (6-minute walk test, index joint pain, and function) for context. Results: At 10 weeks, 158 participants were available for follow-up; 120 (76%) provided diaries, with 113 providing generic or brand names for the pain relief purchased. In the IR group, 60% (33/55) reported the purchase of opioid-based medications after discharge compared with 34% (20/58) in the home group (χ2 = 7.4; P = 0.007); thus, the risk of purchasing opioids for those in the IR group was almost double (RR, 1.7 [95% CI, 1.1-2.6]). No significant or meaningful between-group differences in index joint pain, function, or mobility were observed. Conclusion: Contrary to what was hypothesized, IR is a strong driver of opioid purchase after discharge from the hospital following TKA.