Table 3.

Relationship between timing of urine neutrophil gelatinase-associated lipocalin measurements and prediction accuracy

VariableBefore CPBWithin 1 h of CPBWithin 1–3 h of CPBWithin 3–6 h of CPBWithin 6–12 h of CPBWithin 12–18 h of CPBWithin 18–24 h of CPBWithin 24–48 h of CPB
Measurements (n)15516618011519917680105
Outcome events (n)141191316161214
Urine creatinine–normalized NGAL concentration (μg/mmol creatinine)
 ROC area (95% CI)a0.689 (0.552 to 0.886)0.736 (0.581 to 0.881)0.719 (0.541 to 0.897)0.755 (0.553 to 0.958)0.762 (0.622 to 0.901)0.775 (0.662 to 0.888)0.747 (0.625 to 0.869)0.441 (0.268 to 0.614)
Absolute urine NGAL concentration (ng/ml)
 ROC area (95% CI)a0.679 (0.512 to 0.847)0.656 (0.458 to 0.853)0.675 (0.510 to 0.841)0.796 (0.632 to 0.960)0.818 (0.708 to 0.927)0.783 (0.675 to 0.892)0.729 (0.572 to 0.887)0.466 (0.288 to 0.645)
Urine NGAL excretion rate (ng/hr)
 ROC area (95% CI)a0.583 (0.418 to 0.749)0.725 (0.572 to 0.878)0.668 (0.454 to 0.882)0.700 (0.525 to 0.876)0.672 (0.531 to 0.812)0.594 (0.445 to 0.743)0.638 (0.473 to 0.803)0.548 (0.349 to 0.746)
  • The outcome events were dialysis requirement and/or in-hospital death. CPB, cardiopulmonary bypass; NGAL, neutrophil gelatinase-associated lipocalin; ROC, receiver-operating characteristic; 95% CI, 95% confidence interval.

  • a 95% CIs were estimated by boot-strapping with 1000 resamples.