The impact of preoperative oral nutrition supplementation on outcomes in patients undergoing gastrointestinal surgery for cancer in low- and middle-income countries: a systematic review and meta-analysis

Malnutrition is an independent predictor for postoperative complications in low- and middle-income countries (LMICs). We systematically reviewed evidence on the impact of preoperative oral nutrition supplementation (ONS) on patients undergoing gastrointestinal cancer surgery in LMICs. We searched EMBASE, Cochrane Library, Web of Science, Scopus, WHO Global Index Medicus, SciELO, Latin American and Caribbean Health Sciences Literature (LILACS) databases from inception to March 21, 2022 for randomised controlled trials evaluating preoperative ONS in gastrointestinal cancer within LMICs. We evaluated the impact of ONS on all postoperative outcomes using random-effects meta-analysis. Seven studies reported on 891 patients (446 ONS group, 445 control group) undergoing surgery for gastrointestinal cancer. Preoperative ONS reduced all cause postoperative surgical complications (risk ratio (RR) 0.53, 95% CI 0.46-0.60, P < 0.001, I-2 = 0%, n = 891), infection (0.52, 0.40-0.67, P = 0.008, I-2 = 0%, n = 570) and all-cause mortality (0.35, 0.26-0.47, P = 0.014, I-2 = 0%, n = 588). Despite heterogeneous populations and baseline rates, absolute risk ratio (ARR) was reduced for all cause (pooled effect -0.14, -0.22 to -0.06, P = 0.006; number needed to treat (NNT) 7) and infectious complications (-0.13, -0.22 to -0.06, P < 0.001; NNT 8). Preoperative nutrition in patients undergoing gastrointestinal cancer surgery in LMICs demonstrated consistently strong and robust treatment effects across measured outcomes. However additional higher quality research, with particular focus within African populations, are urgently required.