Association Between Initial Prescription Size and Likelihood of Opioid Refill After Total Knee and Hip Arthroplasty.

Background: The present study was designed to test the hypothesis that there was no association between initial opioid prescription size and the likelihood of refill after elective primary total knee (TKA) and hip arthroplasty (THA).

Methods: We retrospectively analyzed large national datasets of commercial and Medicare insurance claims to identify a weighted cohort of 120,889 primary total joint arthroplasties (76,900 TKA and 43,989 THA) comprised of opioid-naive patients aged 18 to 75 years who had surgery between January 2015 and November 2019. The primary outcome was refill of any prescription opioid medication within 30 days after discharge, and the primary predictor variable was the total amount of opioid filled in the initial discharge prescription measured in oral morphine equivalents (OMEs). Logistic regressions were used to estimate the likelihood of refill, given a particular prescription size while adjusting for multiple patient factors, including age, sex, comorbidities, and year of surgery.

Results: The 30-day refill rate was 59.6% following TKA and 26.1% for THA. Adjusted odds of refill decreased by 2% for every 75 OME (10 tablets of 5 mg oxycodone) increase to the initial prescription size among the THA cohort (adjusted odds ratio [OR] = 0.98; 95% CI 0.97-0.99), and decreased by 3% for the TKA cohort (aOR = 0.97; 95% CI 0.97-0.98).

Conclusion: These nationally representative data demonstrated that larger initial opioid prescription size was associated with small but clinically insignificant decreases in 30-day refill after total joint arthroplasty. This finding should allay concerns about efforts to decrease postsurgical opioid prescribing.