Protocol for an individual patient data meta-analysis for the assessment of risk factors affecting the development and outcome of functional and structural acute kidney injury after cardiac surgery: the METARIS CS-AKI study

Abstract

Abstract Introduction In addition to serum creatinine (SCr), a kidney functional biomarker, structural damage biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) may improve identification of patients at risk of adverse outcomes after cardiac surgery. Previous meta-analyses have relied on study-level data, functional acute kidney injury (AKI) definitions and heterogeneous NGAL cut-off concentrations, limiting comparability and clinical interpretation. Methods and analysis We will conduct an individual patient data (IPD) meta-analysis of prospective studies investigating NGAL in adult patients undergoing cardiac surgery. Authors of eligible studies will be contacted to provide IPD according to a prespecified data request form. Primary outcomes will be the AKI incidence, initiation of renal replacement therapy and in-hospital mortality after surgery. SCr and NGAL will be analysed both as continuous predictors and using study-specific as well as harmonised IPD-derived cut-off values to characterise AKI phenotypes and predictors of adverse outcomes enabling the quantification of risk across the full spectrum of NGAL and SCr concentrations. Exploratory analyses using mixed-effects logistic regression models will investigate patient-level characteristics that may modify clinical risk for the development of AKI and related adverse outcomes. The study results will be reported in accordance with the Preferred Reporting Items for a Systematic Review and Meta-Analysis of Individual Participant Data. The findings may improve biomarker-guided risk stratification after cardiac surgery. Ethics and dissemination Ethics approval was obtained for all included studies by the respective ethics committees or institutional review boards. This meta-analysis is exempt from additional ethical approval because it uses anonymised data from previously published studies with informed consent already obtained. Findings will be disseminated through national and international conferences and may be published in separate peer-reviewed articles according to the scope of the analyses. PROSPERO registration number CRD420261336943.