Statistical analysis
Continuous variables are presented as medians and 25-75, (25-75 median percentiles) as data were not normally distributed and categorical variables are expressed as frequencies and percentages. Mann-Whitney test was used in univariate analysis of continuous variables and the Person Chi-square test or Fisher’s exact test was used to analyze categorical variables.
Results
Table 2 showed the demographic and clinical characteristics of pediatric patients who were subjected to cardiac surgery. Those were divided into 2 groups according to the occurrence of acute kidney injury, most of all pediatric patients were in age group > 30 days- ≤2 years (n=329, 57.9%), and least was ≥ 13- < 18 years (n= 31, 5.5%). The males were greater than females (54.9% versus 45.1%); Non-Saudi patients were more than Saudi (82.4% versus 17.6%). The same distributions of age, gender, and nationality were found in patients with and without AKI with insignificant differences between them (P =0.092, P =0.600, and P =0.784, respectively). The median of CPB and ACX durations were 68 and 48 min that was significantly prolonged in patients with AKI versus those without AKI (79 versus 64 min and 57 versus 45, P < 0.0001 for both). Case urgency was mostly elective than emergent in all patients (82.6% versus 17.4%) and the same distribution in patients with and without AKI. Regarding creatinine levels, preoperative SCr was significantly higher in patients without AKI versus those with AKI (P <0.0001), meanwhile, post-operative creatinine levels, the difference between post- and pre-operative creatinine, and percentage changes of creatinine were significantly lower in patients without AKI versus patients with AKI (P <0.0001 for all). Stages of AKI were stage I (54.4%), then stage II (30.7%), and lastly stage III (14.9%). Death within index hospitalization was significantly higher in patients with AKI versus those without (7% versus 1.5%, P =0.004).
Table 3 showed the demographic and clinical characteristics of adult patients who were subjected to cardiac surgery. The patients were divided into 2 groups according to the occurrence of acute kidney injury, Adult patients who developed AKI were found in the age group 60-69 years; while those who did not develop AKI were in age group <50 years with a significant difference in age group distribution of patients (P =0.004). The male was higher than female in both adult patients with AKI and without AKI (P =0.384); Non-Saudi were higher than Saudi in both adult patients with AKI and without AKI (P =0.143); Surgery type was mostly coronary artery bypass graft (CABG) in both adult patients with AKI and without AKI (P =0.235); valve replacement was mostly mechanical than biologic in both adult patients with AKI and without AKI (P =0.588). The number of grafts in adult patients with AKI was 1 in 12.1% (n= 13), 2 in 28.0% (n= 30), 3 in 17.8% (n= 19) and 4 in 6.5% (n= 7); while graft numbers in patients without AKI were 1 in 7.5% (n= 20), 2 in 19.2% (n= 51), 3 in 22.2% (n= 59) and 4 in 4.3% (n= 16) with significant difference between them (P =0.046). Adult patients with AKI were significantly higher than adult patients without AKI in median of CPB (P =0.003), pre-existing hypertension (57.9% versus 42.5%, P =0.008), pre-operative creatinine level (P <0.0001), postoperative creatinine level (P <0.0001), difference between pre-and post-operative creatinine level (P <0.0001), percentage changes creatinine level (P <0.0001) and death within index hospitalization (13.1% versus 2.6%, P <0.0001). Stages of AKI were mostly stage I (68.2%), then stage II (18.7%), and lastly stage III (13.1%) (Table 3).
Table (2): Characteristics of pediatrics patients undergoing cardiac surgery according to the occurrence of acute kidney injury (AKI).