Table 2.
NGAL Cutoff Concentrations for AKI End Points, Corresponding Sensitivity and Specificity and Predictive Indexes Derived From the Individual-Study-Data Meta-analysis
| Biomarker | Criterion | Cutoff, ng/mL | Sensitivity, % (95% CI) | Specificity, % (95% CI) | LR + | LR − | DOR | Prevalence, % | PPV, % | NPV, % |
|---|---|---|---|---|---|---|---|---|---|---|
| AKI End Point | ||||||||||
| Urinary NGAL |
95% sensitivity | 5 | 95 (91–99) | 12 (4–21) | 1.08 | 0.42 | 2.6 | 26.3 | 27.8 | 87.1 |
| Youden | 81 | 56 (43–70) | 71 (57–85) | 1.93 | 0.62 | 3.1 | 26.3 | 40.8 | 81.9 | |
| 95% specificity | 541 | 20 (10–30) | 95 (91–99) | 4.00 | 0.84 | 4.8 | 26.3 | 58.8 | 76.9 | |
| Plasma NGAL |
95% sensitivity | 71 | 95 (91–100) | 22 (14–31) | 1.22 | 0.23 | 5.4 | 20.3 | 23.7 | 94.5 |
| Youden | 165 | 66 (50–81) | 73 (63–83) | 2.44 | 0.47 | 5.2 | 20.3 | 38.4 | 89.4 | |
| 95% specificity | 311 | 30 (15–45) | 95 (92–98) | 6.00 | 0.74 | 8.1 | 20.3 | 60.4 | 84.2 | |
| Severe AKI End Point | ||||||||||
| Urinary NGAL |
95% sensitivity | 12 | 95 (90–100) | 21 (7–35) | 1.20 | 0.24 | 5.1 | 11.9 | 14.0 | 96.9 |
| Youden | 105 | 65 (46–84) | 71 (55–87) | 2.24 | 0.49 | 4.5 | 11.9 | 23.2 | 93.8 | |
| 95% specificity | 580 | 27 (10–45) | 95 (90–100) | 5.40 | 0.77 | 7.0 | 11.9 | 42.2 | 90.6 | |
| Plasma NGAL |
95% sensitivity | 79 | 100 (89–100) | 33 (17–41) | 1.49 | 0.00 | 9.4 | 9.5 | 13.5 | 100.0 |
| Youden | 231 | 67 (46–77) | 89 (76–92) | 6.09 | 0.37 | 16.4 | 9.5 | 39.0 | 96.3 | |
| 95% specificity | 364 | 44 (23–55) | 100 (91–100) | NA | 0.56 | 14.9 | 9.5 | 100.0 | 94.4 | |
| AKI-D End Point | ||||||||||
| Urinary NGAL |
95% sensitivity | 26 | 95 (89–100) | 39 (20–58) | 1.56 | 0.13 | 12.1 | 3.5 | 5.3 | 99.5 |
| Youden | 83 | 78 (65–91) | 67 (49–84) | 2.36 | 0.33 | 7.2 | 3.5 | 7.9 | 98.8 | |
| 95% specificity | 589 | 24 (10–38) | 95 (90–100) | 4.80 | 0.80 | 6.0 | 3.5 | 14.8 | 97.2 | |
| Plasma NGAL |
95% sensitivity | 162 | 95 (88–100) | 59 (41–77) | 2.32 | 0.08 | 27.3 | 6.3 | 13.5 | 99.4 |
| Youden | 214 | 87 (73–100) | 71 (55–87) | 3.00 | 0.18 | 16.4 | 6.3 | 16.8 | 98.8 | |
| 95% specificity | 546 | 26 (5–47) | 95 (90–100) | 5.20 | 0.78 | 6.7 | 6.3 | 25.9 | 95.0 | |
Note: The identified cutoff concentrations require prospective evaluation.
Abbreviations: AKI, acute kidney injury; AKI-D, acute kidney injury with dialysis; CI, confidence interval; DOR, diagnostic odds ratio; LR +/−, positive or negative likelihood ratio; NGAL, neutrophil gelatinase-associated lipocalin; NPV, negative predictive value; PPV, positive predictive value.