Variation in opioid filling after same-day breast surgery in Ontario, Canada: a population-based cohort study

BACKGROUND: Postoperative pain management practices in breast surgery are variable, with recent evidence that approaches for minimizing or sparing opioids can be successfully implemented. We describe opioid filling and predictors of higher doses in patients undergoing same-day breast surgery in Ontario, Canada. METHODS: In this retrospective population-based cohort study, we used linked administrative health data to identify patients aged 18 years or older who underwent same-day breast surgery from 2012 to 2020. We categorized procedure types by increasing invasiveness of surgery: partial, with or without axillary intervention (P ± axilla); total, with or without axillary intervention (T ± axilla); radical, with or without axillary intervention (R ± axilla); and bilateral. The primary outcome was filling an opioid prescription within 7 or fewer days after surgery. Secondary outcomes were total oral morphine equivalents (OMEs) filled (mg, median and interquartile range [IQR]) and filling more than 1 prescription within 7 or fewer days after surgery. We estimated associations (adjusted risk ratios [RRs] and 95% confidence intervals [CIs]) between study variables and outcomes in multivariable models. We used a random intercept for each unique prescriber to account for provider-level clustering. RESULTS: Of the 84 369 patients who underwent same-day breast surgery, 72% (n = 60 620) filled an opioid prescription. Median OMEs filled increased with invasiveness (P ± axilla = 135 [IQR 90–180] mg; T ± axilla = 135 [IQR 100–200] mg; R ± axilla = 150 [IQR 113–225] mg, bilateral surgery = 150 [IQR 113–225] mg; p < 0.0001). Factors associated with filling more than 1 opioid prescription were age 30–59 years (v. age 18–29 yr), increased invasiveness (RR 1.98, 95% CI 1.70–2.30 bilateral v. P ± axilla), Charlson Comorbidity Index ≥ 2 versus 0–1 (RR 1.50, 95% CI 1.34–1.69) and malignancy (RR 1.39, 95% CI 1.26–1.53). INTERPRETATION: Most patients undergoing same-day breast surgery fill an opioid prescription within 7 days. Efforts are needed to identify patient groups where opioids may be successfully minimized or eliminated.