Miss Natalie Pavlovic1,2, Dr Robert Boland2,3, Dr Bernadette Brady3,4,5, Dr Furkan Genel6,7, Professor Ian Harris1,5,7, Professor Victoria Flood8,9, A/Professor Justine Naylor1,7
1South Western Sydney Clinical School, University of New South Wales, 2Fairfield Hospital, South Western Sydney Local Health District, Prairiewood, 2176, Australia, 3Discipline of Physiotherapy, Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, 2006, Australia, 4Western Sydney University, School of Science and Health, Campbelltown, 2560, Australia, 5Liverpool Hospital, South Western Sydney Local Health District, Liverpool, 2170, Australia, 6St George and Sutherland Clinical School, University of New South Wales, , Australia, 7Whitlam Orthopaedic Research Centre, Ingham Institute, South Western Sydney Local Health District, 8Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, 2006, Australia, 9Westmead Hospital, Western Sydney Local Health District, Westmead, 2145, Australia
To determine the effects of weight-loss diets before elective surgery on postoperative outcomes in people with obesity.
MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, CENTRAL, CINAHL, Scopus, ClinicalTrials.gov and WHO ICTRP databases were searched from inception to July 2020. Study eligibility was assessed by two independent researchers; criteria for inclusion were prospective cohort studies or randomised controlled trials assessing the effect of weight-loss diets compared to standard care on postoperative outcomes in adults with obesity awaiting elective surgery. Participants with a history of cancer or those undergoing bariatric surgery were excluded. Data on postoperative complications to 90 days, preoperative weight change, length of stay and patient-reported outcome measures were extracted and synthesised in meta-analyses.
Three randomised controlled trials were eligible, involving 173 participants. One study involved total knee arthroplasty and two investigated general surgery. Each study compared low-calorie diets using meal replacement formulas to usual care. There is very low-quality evidence of a statistically significant difference favouring the intervention for preoperative weight loss (MD -6.67kg, 95%CI-12.09kg to -1.26kg; P=0.02). The pooled effect estimate suggested low-quality evidence that preoperative weight-loss diets do not reduce postoperative complications to 30 days (OR 0.34, 95%CI 0.08 to 1.42; P=0.14) or length of hospital stay (MD -3.72 hours, 95%CI -10.76 to 3.32; P=0.30).
From limited data, participation in weight-loss diets does not reduce postoperative complications and length of stay after elective surgery. Further high-quality and adequately powered prospective trials are needed to evaluate weight-loss diets before elective surgery on postoperative outcomes.
Natalie Pavlovic is currently a PhD student at the University of New South Wales. Her thesis is focused on investigating the relationship between osteoarthritis and obesity on postoperative complications in patients undergoing total hip or knee arthroplasty procedures.