Effect of body mass index on clinical outcomes after robotic cardiac surgery: is there an obesity paradox?

Abstract

Background To investigate the effect of body mass index (BMI) on clinical outcomes after robotic cardiac surgery, and to explore the postoperative obesity paradox. Methods The data of 146 patients who underwent robotic cardiac surgery under cardiopulmonary bypass (CPB) from July 2016 to June 2022 in Daping Hospital of Army Medical University were retrospectively analyzed, and their demographic data and related clinical data were statistically analyzed. The mean age was (42.88 ± 13.01) years, 55 (37.67%) were male and 91 (62.33%) were female. Patients were divided into 3 groups according to preoperative BMI: lean group (BMI < 18.5 kg/m2; n = 17; 11.64%), normal group (BMI 18.5 kg/m2 to 23.9 kg/m2; n = 81; 55.48%), and overweight and obese group (BMI ≥ 24 kg/m2; n = 48; 32.88%). Multivariate analysis was performed to compare clinical outcomes across BMI groups. Results Preoperative data in different BMI groups showed that there were statistically significant differences in age, height, weight, body surface area (BSA), diabetes, left atrial anteroposterior diameter (LAD), triglyceride (TG), and high-density lipoprotein (HDL) (all P < 0.05). Postoperative clinical outcomes showed that there was no statistical difference between the lean group and the normal group; the intensive care unit stay and postoperative hospital stay in the overweight and obese group were significantly higher than those in the normal group (P < 0.05), and the risk of postoperative cardiac surgery-related acute kidney injury (CSA-AKI) was significantly increased (P = 0.021); further Multiple Binary Logistic Regression Analysis suggested that preoperative TG (OR = 1.772, 95% CI 1.068–2.942, P = 0.027) and operation time ≥ 300 min (OR = 3.823, 95% CI 1.098–13.308, P = 0.035) were independent risk factors for postoperative CSA-AKI. Conclusions Overweight and obese patients had significantly prolonged intensive care unit stay and postoperative hospital stay after robotic cardiac surgery, and significantly increased incidence of postoperative CSA-AKI, which did not support the obesity paradox; preoperative TG and operation time ≥ 300 min were independent risk factors for postoperative CSA-AKI.

Low Body Mass Index Versus Obesity: Which is Worse During Cardiac Surgery?

“…In our study, similar to the results of Wu et al (7), the duration of intubation, ICU stay, and hospital stay in the OBMI patient group was significantly longer than that of all other groups. Apart from all these, postoperative surgical revision and even mortality rates were similar in all groups.…”

“…While at first glance, the operative and postoperative data of obese patients were expected to be poor, many studies conducted on obese patients showed that the results were much better, and they termed this phenomenon "the obesity paradox" (4). After the emergence of this idea, many articles were written on this subject, and it was reported in these articles that such a paradox did not exist and that the results were worse in obese patients (7,8). While the issue of obesity has been examined many times in scientific research, the situation of patients with lower-than-normal BMI has been somewhat overlooked, especially in cardiac surgery.…”

“…Although Stamou et al (5) stated that the results were better in obese patients, it is noteworthy that the obese patients in their study were younger than the other patients. In a recently published article, Wu et al (7) reported that in patients who underwent robotic cardiac surgery, the intensive care period was prolonged, and postoperative kidney damage was higher in the obese patient group. Thus, they concluded that the obesity paradox did not exist.…”