Abstract
Background: Female patients are at an increased risk of experiencing severe postoperative pain and developing chronic pain after cardiac surgery. However, the impact of sex on postoperative opioid administration is underexplored.
Methods: This single-centre retrospective cohort study included adults undergoing coronary artery bypass grafting, valve surgery, or a combined procedure at a quaternary referral hospital, between November 2012 and June 2021. Patients were classified as female or male based on biological sex. Opioid doses were converted to oral morphine equivalent daily doses (oMEDDs) to enable comparisons. Energy balancing was used to adjust for baseline differences, including body weight and other confounders. Sex differences in gabapentinoid and antipsychotic drug administration were also evaluated. The aim of this study was to evaluate the association of patient sex and perioperative opioid administration after cardiac surgery.
Results: We studied 3188 patients: 825 (25.9%) females and 2363 (74.1%) males. After adjusting for body weight and other confounders, female patients received significantly less opioid analgesia on postoperative day 1 (oMEDD difference: -5.70 mg [95% confidence interval {CI}: -3.15 to -8.25], p < 0.0001), day 2 (oMEDD difference: -9.06 mg [95% CI: -5.05 to -13.08], p < 0.0001), and day 3 (oMEDD difference: -4.50 mg [95% CI: -0.52 to -8.47], p < 0.03). Female patients were also more likely to be prescribed a gabapentinoid (odds ratio: 1.47 [95% CI: 1.02 to 2.13], p = 0.04) but less likely to be prescribed an antipsychotic (odds ratio: 0.63 [95% CI: 0.46-0.86], p = 0.004).
Conclusion: In a single-centre cohort study involving over 3000 cardiac surgery patients, female sex was associated with the administration of significantly lower doses of postoperative opioid. Providers involved in the care of cardiac surgery patients should be aware of the potential for implicit bias, and further studies are required to identify mechanisms for the observed disparities.