STUDY DESIGN: Literature-based meta-analysis and individual-study-data meta-analysis of diagnostic studies following PRISMA-IPD guidelines.

SETTING & STUDY POPULATIONS: Studies of adults investigating AKI, severe AKI, and AKI-D in the setting of cardiac surgery, intensive care, or emergency department care using either urinary or plasma NGAL measured on clinical laboratory platforms.

SELECTION CRITERIA FOR STUDIES: PubMed, Web of Science, Cochrane Library, Scopus, and congress abstracts ever published through February 2020 reporting diagnostic test studies of NGAL measured on clinical laboratory platforms to predict AKI.

DATA EXTRACTION: Individual-study-data meta-analysis was accomplished by giving authors data specifications tailored to their studies and requesting standardized patient-level data analysis.

ANALYTICAL APPROACH: Individual-study-data meta-analysis used a bivariate time-to-event model for interval-censored data from which discriminative ability (AUC) was characterized. NGAL cutoff concentrations at 95% sensitivity, 95% specificity, and optimal sensitivity and specificity were also estimated. Models incorporated as confounders the clinical setting and use versus nonuse of urine output as a criterion for AKI. A literature-based meta-analysis was also performed for all published studies including those for which the authors were unable to provide individual-study data analyses.

RESULTS: We included 52 observational studies involving 13,040 patients. We analyzed 30 data sets for the individual-study-data meta-analysis. For AKI, severe AKI, and AKI-D, numbers of events were 837, 304, and 103 for analyses of urinary NGAL, respectively; these values were 705, 271, and 178 for analyses of plasma NGAL. Discriminative performance was similar in both meta-analyses. Individual-study-data meta-analysis AUCs for urinary NGAL were 0.75 (95% CI, 0.73-0.76) and 0.80 (95% CI, 0.79-0.81) for severe AKI and AKI-D, respectively; for plasma NGAL, the corresponding AUCs were 0.80 (95% CI, 0.79-0.81) and 0.86 (95% CI, 0.84-0.86). Cutoff concentrations at 95% specificity for urinary NGAL were>580ng/mL with 27% sensitivity for severe AKI and>589ng/mL with 24% sensitivity for AKI-D. Corresponding cutoffs for plasma NGAL were>364ng/mL with 44% sensitivity and>546ng/mL with 26% sensitivity, respectively.

LIMITATIONS: Practice variability in initiation of dialysis. Imperfect harmonization of data across studies.

METHODS: Parameters influencing corticosteroid (CS) dosing were identified (step 1). Data from children with proliferative LN were used to generate patient profiles (step 2). Physicians rated changes in renal and extrarenal childhood-onset SLE activity between 2 consecutive visits and proposed CS dosing (step 3). The SSR was developed using patient profile ratings (step 4), with refinements achieved in a physician focus group (step 5). A second type of patient profile describing the course of childhood-onset SLE for ≥4 months since kidney biopsy was rated to validate the SSR-recommended oral and intravenous (IV) CS dosages (step 6). Patient profile adjudication was based on majority ratings for both renal and extrarenal disease courses, and consensus level was set at 80%.

RESULTS: Degree of proteinuria, estimated glomerular filtration rate, changes in renal and extrarenal disease activity, and time since kidney biopsy influenced CS dosing (steps 1 and 2). Considering these parameters in 5,056 patient profile ratings from 103 raters, and renal and extrarenal course definitions, CS dosing rules of the SSR were developed (steps 3-5). Validation of the SSR for up to 6 months post-kidney biopsy was achieved with 1,838 patient profile ratings from 60 raters who achieved consensus for oral and IV CS dosage in accordance with the SSR (step 6).