Indications, trends, and perioperative outcomes of minimally invasive and open liver surgery in non-obese and obese patients: an international multicentre propensity score matched retrospective cohort study of 9963 patients

Background: Despite the worldwide increase of both obesity and the use of minimally invasive liver surgery (MILS), evidence regarding the safety and eventual benefits of MILS in obese patients is scarce. The aim of this study was therefore to compare the outcomes of non-obese and obese patients (BMI 18.5-29.9 and BMI≥30, respectively) undergoing MILS and OLS, and to assess trends in MILS use among obese patients.Methods: In this retrospective cohort study, patients operated at 20 hospitals in eight countries (2009-2019) were included and the characteristics and outcomes of non-obese and obese patients were compared. Thereafter, the outcomes of MILS and OLS were compared in both groups after propensity-score matching (PSM). Changes in the adoption of MILS during the study period were investigated.Resuls: Overall, 9963 patients were included (MILS: n = 4687; OLS: n = 5276). Compared to non-obese patients (n = 7986), obese patients(n = 1977) were more often comorbid, less often received preoperative chemotherapy or had a history of previous hepatectomy, had longer operation durations and more intraoperative blood loss (IOBL), paralleling significantly higher rates of wound- and respiratory-related complications. After PSM, MILS, compared to OLS, was associated, among both non-obese and obese patients, with less IOBL (200 ml vs 320 ml, 200 ml vs 400 ml, respectively), lower rates of transfusions (6.6% vs 12.8%, 4.7% vs 14.7%), complications (26.1% vs 35%, 24.9% vs 34%), bile leaks(4% vs 7%, 1.8% vs 4.9%), liver failure (0.7% vs 2.3%, 0.2% vs 2.1%), and a shorter length of stay(5 vs 7 and 4 vs 7 days). A cautious implementation of MILS over time in obese patients (42.1%-53%, p < .001) was paralleled by stable severe morbidity (p = .433) and mortality (p = .423) rates, despite an accompanying gradual increase in surgical complexity.Conclusions: MILS is increasingly adopted and associated with perioperative benefits in both non-obese and obese patients.