How outcomes are defined in randomized controlled trials of acute kidney injury: a scoping review

Research on acute kidney injury (AKI) is hindered by heterogeneous definitions, measurements, and follow-up periods, which limit comparability across randomized controlled trials (RCTs) and the translation of findings into evidence-based practice. This review aimed to describe outcomes reported in RCTs of AKI prevention and treatment.

This scoping review followed PRISMA-ScR guidance. PubMed, Embase, Web of Science, and Cochrane CENTRAL were searched for RCTs published between January 2014 and April 2024. Eligible studies included adults or children with AKI or at risk for AKI. Outcomes were categorized using the COMET taxonomy according to core area, core domain, specific domain, measurement method, and timing.

Among 3921 abstracts screened, 251 RCTs were included. Prevention trials represented 197/251 (78.5%). Most outcomes belonged to the Physiological/Clinical Core Area (194/197, 98.5%), in the Renal outcomes Core Domain (186/197, 94%). Renal function (162/197, 82%) and renal damage (15/197, 7.5%) were the most frequent domains. Measurements relied mainly on serum creatinine, alone (130/162, 80%) or combined with urine output (25/162, 15%), assessed between 48-72 h (65%) and 7 days (22%). Outcomes in therapeutic RCTs (54/251, 21.5%) belonged to the Physiological/Clinical (37/54, 69%) and Mortality/Survival (14/54, 26%) Core Areas. Renal outcomes (33/54, 61%) included renal function (9/54, 17%), renal recovery (10/54, 19%), and use of RRT (3/54, 6%). Measurements included serum creatinine (16/54, 30%), mortality (14/54, 26%) and estimated glomerular filtration rate (eGFR) (3/54, 6%), assessed between 7 and 90 days.

Outcome reporting is heterogeneous, highlighting the need for a standardized core outcome set.