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.