Incidence, risk factors, and outcomes of early postoperative hyperglycemia in surgical patients: a protocol for a systematic review and meta-analysis

Background: Early postoperative hyperglycemia (POHG) is common and associated with poor postoperative outcomes. Currently, there is no systematic review and meta-analysis that addresses the knowledge gap of the incidence of POHG in surgical patients and that explores the associated risk factors and complications. The objective of this study will be to estimate the pooled incidence, risk factors, and clinical outcomes of early postoperative hyperglycemia in men and women globally. Methods: We designed and registered a study protocol for a systematic review and meta-analysis of studies reporting the incidence of postoperative hyperglycemia (POHG). We will search PubMed (MEDLINE), Scopus, Web of Science, EMBASE, Cochrane Library, OVID (HEALTH STAR), OVID (MEDLINE), and Joana Briggs Institute EBF Database (from inception onwards). Randomized controlled trials and observational cohort studies reporting the incidence of POHG and conducted in surgical patients will be included. No age, geographical location, study design, or language limits will be applied. The primary outcome will be the incidence of POHG. Secondary outcomes will be risk factors and clinical outcomes of POHG. Two reviewers will independently screen citations, full text articles, and abstract data, extract data, and evaluate the quality and bias of included studies. Discrepancies will be resolved through discussion or consultation with a third researcher. The risk of bias and study methodological quality of included studies will be evaluated by the appropriate Cochrane risk of bias tool for randomized trials and Newcastle-Ottawa Scale for cohort studies. If feasible, we will conduct random effects meta-analysis with a logit transformation of proportions. We will report the probability of postoperative hyperglycemia as a measure of incidence rate, relative risk ratios (RR), and 95% confidence intervals to report the effects of the risk factors and postoperative outcomes. Additional analyses will be conducted to explore the potential sources of heterogeneity (e.g., age, gender, geographical location, publication year, comorbidities, type of surgical procedure). The Egger test and funnel plots will be used to assess small study effects (publication bias). Discussion: This systematic review and meta-analysis will identify, evaluate, and integrate the evidence on the incidence, risk factors, and outcomes of early POHG in surgical patients. The results of this study can be used to identify populations which may be at particular risk for POHG. Future studies which use this information to better guide post-operative glycemic control in surgical patients could be considered.