Variable Age (mean ± SD) [months] Sex (M/F) Clinical diagnosis Large VSD [%] TGA with VSD-ASD [%] VSD-DORV [%] ASD [%] Others† [%] Dialysis requirement, n (%)* Non-survivors, n (%)** Patients (n = 40) 20.75 ±23.33 20/20 40 15 12.5 10 22.5 4 (10) 9 (22.5) *Patients were all males with cyanotic heart conditions, **6 patients had multiple organ failure, 3 suffered from cardiovascular failure; †include hypoplastic right ventricle with VSD and ASD; VSD-ASD with patent ductus arteriosus; TGA without VSD VSD – ventricular septal defect, TGA – transposition of great arteries, ASD – atrial septal defect, DORV – double-outlet right ventricle Statistical analysis The data were analyzed using Statistical Pack- age for Social Sciences (SPSS) version 14. A p value of < 0.05 was considered significant. Unpaired Stu- dent's t-test was used to assess the statistical sig- nificance of the difference between two population means in a study involving independent samples. The multiple regression test was used for assess- ing multiple linear regressions aiming to find a lin- ear relationship between a response variable and several possible predictors. Correlation analysis was used for assessing the strength of association between two variables. The correlation coefficient (r) defines the strength and direction of the linear relationship between two variables. Cut-off levels for sensitivity and specificity were determined using χ2; Fisher exact test was performed in tables con- taining a value less than 5. Results The demographic data of the patients enrolled in the present study are shown in Table I. Patients were classified according to pediatric RIFLE criteria (2) into: 1 – 8 patients (20%) with no evidence or risk of AKI; 2 – 13 (32.5%) at risk for developing AKI (AKI grade I equivalent to RIFLE: Risk); 3 – 15 (37.5%) showing evidence of AKI without failure (AKI grade II equivalent to RIFLE: Injury; and, 4 – 4 (10%) suffer- ing from acute renal failure (AKI grade III equiva- lent to RIFLE: Failure). For statistical reasons, the patients were divided into two groups: group I: patients who suffered AKI grades II and III (RIFLE: Injury and Failure); group II: patients who did not develop AKI or at risk (AKI grade I, RIFLE: Risk). Comparison of serial plasma NGAL levels between patients of group I versus patients of group II is represented in Table II, and showed high- ly significant elevations in mean plasma NGAL lev- els in group I patients at 2, 12, and 24 h after sur- gery (p < 0.0001). In Table III, significant correlations are shown between NGAL and creatinine at different time inter- vals, especially most evident at 12 and 24 h after sur- gery. Figure 1 shows the correlation coefficient (r) of plasma NGAL versus serum creatinine with acute kid- ney injury at varying time intervals (2, 12, and 24 h after surgery). Highly significant correlations (p < 0.0001) were recorded for plasma NGAL and AKI at 2, 12 and 24 h after surgery (r = 0.893, r = 0.873, and r = 0.795 respectively). However, for serum cre- atinine, highly significant correlations with AKI were delayed and existed at 12 and 24 h post-operatively (0.609 and 0.711 respectively). Several cut-off levels were analyzed to explore the sensitivity and speci- ficity of plasma NGAL to detect AKI grades II and III. A cut-off level of 100 ng/ml 2 h after surgery and 125 ng/ml at 12 h after surgery both recorded the highest accuracy, being 95% accurate, with sensitiv- ity of 100% and 89.5% respectively, and specificity of 90.5% and 100% respectively. Our results show that sepsis was significantly evident in group I patients compared to group II (p = 0.034). Since it was observed that 72.5% of cases (29 patients) showed evidence of sepsis, diag- nosed by an increase in total leukocytic count num- ber associated by evident shift of band cells to the left during the first 48 h after surgery or by positive F.I. Fadel, A.M.O. Abdel Rahman, M. Farouk Mohamed, S.A. Habib, M.H. Ibrahim, Z.S. Sleem, H.M. Bazaraa, M.M.A. Soliman Table I. Demographic data of studied children Value of p 0.2483 < 0.0001* < 0.0001* < 0.0001* Arch Med Sci 2, April / 2012 Table II. Comparison of serial plasma NGAL levels between patients of group I versus patients of group II Plasma NGAL [ng/dl] Group I Group II AKI Grade II and III (n = 19) No AKI and AKI grade I (n = 21) Mean 42.58 154.79 201.79 238.74 SD ±16.51 ±51.14 ±54.89 ±71.92 Mean 36.17 66.05 83.67 108.05 SD ±15.12 ±20.26 ±21.59 ±26.49 Before surgery 2 h after surgery 12 h after surgery 24 h after surgery 252 *Highly significant difference; NGAL – neutrophil gelatinase associated lipocalin, AKI – acute kidney injury