Sex differences in moderate-to-severe pain in the Post-Anesthesia Care Unit after elective thoracic surgery: a single-center retrospective cohort study

Sex differences in pain perception and analgesic response have become increasingly recognized; however, their impact on moderate-to-severe postoperative pain following elective thoracic surgery remains poorly characterized. Adult patients who underwent elective thoracic surgery were enrolled and stratified into two groups by sex. The primary outcome was the incidence of moderate-to-severe pain in the Post-Anesthesia Care Unit (PACU). Secondary outcomes included the incidence and severity of moderate and severe pain in the PACU, postoperative hospital length of stay, time to first ambulation, and time to chest tube removal. Following propensity score matching (PSM), univariate logistic regression was performed to assess the association between sex and the incidence of moderate-to-severe pain in the PACU. Sensitivity analyses were conducted using three distinct models. Subgroup analyses using multivariable logistic regression were carried out to validate the effect of sex on moderate-to-severe pain in the PACU across different patient populations. A multivariate logistic regression model was employed to identify risk factors for moderate-to-severe pain in the PACU, and a receiver operating characteristic (ROC) curve was generated. An exploratory mediation analysis was conducted to examine potential mediating effects of moderate-to-severe pain in the PACU. A total of 12,075 patients were initially enrolled, with 2,974 patients included in the final analysis after PSM. The incidence of moderate-to-severe pain in the PACU was significantly higher in males than in females (4.17% vs. 2.56%, p = 0.01). In addition, males had a significantly longer time to chest tube removal and a longer postoperative hospital length of stay compared with females. The exploratory mediating effect of moderate-to-severe pain in the PACU on postoperative hospital length of stay and time to chest tube removal was not statistically significant. ROC curve analysis showed that the area under the curve (AUC) of the multivariable logistic regression model was 0.88 (95% CI 0.80–0.95), indicating moderate discrimination of the model within this dataset. Among patients undergoing elective thoracic surgery, males exhibited a slightly higher incidence of moderate-to-severe pain in the PACU, as well as longer time to chest tube removal and postoperative hospital stay compared with females. However, the absolute differences were modest and should be interpreted cautiously in the context of potential residual confounding. These findings are hypothesis-generating and should not be used to support sex-specific analgesic strategies in routine clinical practice.