Is there a role for preoperative liver reducing diet in hepatectomy? A systematic review

Purpose: Preoperative very low-calorie diets (VLCDs) have been shown to reduce liver volume, reduce the risk of liver injury and improve safety during bariatric surgery. Hepatic steatosis (HS) has been associated with poorer outcomes in liver resection. VLCD can be used to improve HS. We aim to explore if preoperative VLCD could improve outcomes for patients with HS undergoing liver resection.

Methods: We performed a systematic review of MEDLINE, EMBASE, PubMed and Cochrane databases. Studies were included if they were full-text articles investigating the effect of a preoperative dietary intervention in patients undergoing liver resection on intra-operative and post-operative outcomes. The last search was performed on 11 Jun 2020. Evidence quality was assessed by "GRADE". A narrative review was undertaken.

Results: Five studies were found: one RCT and four cohort studies including 133 patients in intervention groups and 181 controls. Three used diet-only strategies and two diet and exercise strategies with varying time courses and monitoring. The quality of evidence assessed by GRADE was "high" for the RCT and "low" for the four cohort studies. Steatosis objectively improved in three studies, with evidence of reduced liver volume and increased attenuation on imaging in one. All studies showed a reduction in body weight and body mass index (BMI). Intra-operative blood loss was decreased following a diet-only intervention in two studies, and liver mobility improved in one. No difference was found in morbidity, mortality or hospital length of stay between intervention and control groups.

Conclusions: There is evidence of poorer outcomes in liver resection patients with existing HS. There is an expected role for a preoperative VLCD to optimise these patients for surgery. Existing publications support this, but diet interventions and outcome measures are inconsistent, and patient numbers are small. There is scope for a well-designed, multi-centre randomised trial to investigate this further.