Dose–response effect of postprocedural elevated cardiac troponin level on adverse clinical outcomes following adult noncardiac surgery: a systematic review protocol of prospective studies

INTRODUCTION: Myocardial injury after noncardiac surgery has been recognised as an important complication associated with short-term and long-term morbidity and mortality. However, whether a higher level of postoperative cardiac troponin (cTn) is associated with a higher incidence of major complications remains controversial. Hence, we will conduct a comprehensive dose–response meta-analysis based on all relevant prospective studies to quantitatively evaluate the association between elevated postoperative cTn levels and short-/long-term adverse clinical outcomes following adult noncardiac surgery. METHODS: We will search the PubMed, EMBase, Cochrane Library, ISI Knowledge via Web of Science, China National Knowledge Infrastructure, Wanfang and VIP databases (from inception until October 2020) to identify all prospective cohort studies using the relevant keywords. The primary outcome will be all-cause mortality. The secondary outcomes will include cardiovascular mortality and major adverse cardiovascular events (MACEs). Univariable or multivariable meta-regression and subgroup analyses will be conducted for the comparison between elevated versus nonelevated categories of postoperative cTn levels. Sensitivity analyses will be used to assess the robustness of our results by removing each included study at one time to obtain and evaluate the remaining overall estimates of all-cause mortality or MACE. To conduct a dose–response meta-analysis for the potential linear or restricted cubic spline regression relationship between postoperative elevated cTn levels and all-cause mortality or MACE, studies with three or more categories will be included. ETHICS AND DISSEMINATION: Ethical approval is waived for the systematic review protocol according to the Institutional Review Board/Independent Ethics Committee of Fuwai Hospital. This meta-analysis will be disseminated through a peer-reviewed journal for publication and conference presentations. PROSPERO REGISTRATION NUMBER: CRD42020173175.