Diagnostic value of neutrophil gelatinase-associated lipocalin for early diagnosis of cardiac surgery-associated acute kidney injury: a meta-analysis

Neutrophil gelatinase-associated lipocalin (NGAL) has been identified as one of the most sensitive and specific biomarkers for predicting cardiac surgery-associated acute kidney injury (CSA-AKI); however, variable performance characteristics have been reported. We therefore performed a diagnostic meta-analysis to investigate the diagnostic accuracy of NGAL in early (within 12 h postoperatively) diagnosis of CSA-AKI using established guidelines. The search was carried out electronically with Medline (through PubMed interface), Embase, Cochrane library, ISI Web of Science, Scopus and ClinicalTrials.gov (up to 5 September 2014), and hand-searching was also done. Two reviewers conducted study inclusion, data extractions and quality assessment of the studies independently. The diagnostic capacity of NGAL for CSA-AKI was assessed using pooled sensitivity and specificity, diagnostic odds ratio (DOR), area under the summary receiver operating characteristic curve (AUC). Meta-Disc 1.4 and STATA 12.0 were used to investigate the source of heterogeneity and to perform the meta-analysis. Twenty-four studies (33 data sets of 4066 patients) were considered, which were all of good methodological quality. The overall pooled sensitivity of NGAL for the diagnosis of AKI was 0.68 95% confidence interval (CI), 0.65-0.70, and specificity was 0.79 (95% CI, 0.77-0.80). The overall pooled positive likelihood ratio and negative likelihood ratio were 3.98 (95% CI, 3.05-5.20) and 0.33 (95% CI, 0.24-0.45), respectively, with a DOR of 13.05 (95% CI, 7.85-21.70). The receiver operating characteristic analysis showed an AUC standard error (SE) of 0.86 (0.02) and with a Q*-value (SE) of 0.79 (0.02). Subgroup analysis showed that NGAL had better predictive ability in neonates/children compared with adults (DOR, 19.37; AUC, 0.89 vs DOR, 8.98; AUC, 0.83), and adults without pre-existing renal insufficiency (PRI) had higher diagnostic value than adults without PRI to predict CSA-AKI (DOR, 15.43; AUC, 0.87 vs DOR, 6.56; AUC, 0.81). Both plasma/serum and urine NGAL had the highly predictive nature for early diagnosis of CSA-AKI (DOR, 13.09; AUC, 0.85 vs DOR, 13.20; AUC, 0.88), while lower DOR and AUC values were shown (DOR, 8.31; AUC, 0.81) when measured using standardized clinical platforms, compared with research-based assays (DOR, 19.22; AUC, 0.89). I(2)-values showed substantial heterogeneity, which mainly stems from characteristics of patient population (P = 0.037). NGAL diagnostic accuracy in early detection of CSA-AKI is high, especially in neonates/children or adults with normal baseline renal function.