Influence of higher body mass index on postoperative nausea and vomiting in patients following thoracic surgery for lung cancer: a propensity score-matched cohort study

This study aimed to quantify the association between body mass index (BMI) and postoperative nausea and vomiting (PONV) within the initial 48 h following thoracic surgery for lung cancer. We then explored whether changes in serum inflammatory factor concentrations were related to BMI during the early postoperative period. We conducted a propensity score-matched (PSM), retrospective cohort study at a specialized tertiary medical center. A total of 194 patients aged 18-80 years who underwent thoracic surgery for lung cancer at Shanghai Pulmonary Hospital between January and June 2021 were enrolled. The primary outcome was the incidence of PONV during the first 48 h after surgery. Nausea, vomiting or retching at different time periods, severe pain, and concentrations of perioperative serum inflammatory factors including CRP, IL-6, IL-12, and IFN-gamma were also assessed. Patients in the high BMI group (BMI >= 25 kg/m2) had a lower incidence of PONV than those in the normal BMI group (18.5-25 kg/m2) within the first 48 h after surgery (22 vs. 50%, p = 0.004). The incidence of nausea was lower at 0-12 h (14.5 vs. 37.1%, p = 0.004) and 12-24 h (8.1 vs. 22.6%, p = 0.025) in the high BMI group after surgery, and the incidence of vomiting was lower at 0-12 h (12.9 vs. 30.6%, p = 0.017) in higher BMI after surgery. We found no significant difference in the incidence of severe pain [severe static pain (p = 0.697) and severe dynamic pain (p = 0.158)]. Moreover, higher concentrations of IL-12 (2.24 +/- 2.67 pg/ml vs. 1.48 +/- 1.14 pg/ml, p = 0.048) and IFN-gamma [1.55 (1.00) pg/ml vs. 1.30 (0.89) pg/ml, p = 0.041] were observed in patients with normal BMI on the first day after surgery. Given this finding, patients with a normal BMI should receive more attention for the prevention of PONV than those with a high BMI following thoracic surgery for lung cancer.Trial registration: http://www.chictr.org.cn and ChiCTR2100052380 (24/10/2021).