Clinically significant contrast induced acute kidney injury after non-emergent cardiac catheterization - risk factors and impact on length of hospital stay

Objective: To evaluate the frequency and risk factors associated with clinically significant contrast-induced nephropathy (CIN) in patients undergoing non-emergent coronary angiography. Study Design: Descriptive study. Place and Duration of Study: The Aga Khan University Hospital, Karachi, from January 2005 to December 2007. Methodology: Case records of patients who underwent coronary angiography with a serum creatinine of ≥ 1.5 mg/dl at the time of procedure were evaluated. Clinically significant contrast induced nephropathy (CSCIN) was defined as either doubling of serum creatinine from baseline value within a week following the procedure or need for emergency hemodialysis after the procedure. Results: One hundred and sixteen patients met the inclusion criteria. Mean age was 64.0 ± 11.5 years, 72% were males. Overall prevalence of CIN was 17% (rise of serum creatinine by ≥ 0.5 mg/dl) while that of clinically significant CIN (CSCIN) was 9.5% (11 patients). Patients with CSCIN had significantly lower left ventricular ejection fraction (p = 0.03, OR: 0.24; 95% CI = 0.06 - 0.91) and higher prevalence of cerebrovascular disease (p < 0.001, OR: 14.66; 95% CI = 3.30 - 65.08). Mean baseline serum creatinine was significantly higher, 3.0 ± 1.5 vs. 2.0 ± 1.1 mg/dl (p = 0.03, OR: 1.47; 95% CI = 1.03 - 2.11) whereas mean GFR estimated by Cockcroft-Gault formula was significantly lower at 25 ± 7.4 vs. 41.0 ± 14.6 ml/minute (p = 0.001, OR = 0.89, 95% CI = 0.84 - 0.95) at the time of procedure in patients with CSCIN. Mean length of hospital stay was significantly higher in this group compared to those without CIN, 9.0 ± 5.1 vs. 3.0 ± 3.2 days (p = 0.001, OR = 1.31, 95% CI = 1.12 - 1.54). Multivariate analysis revealed low GFR (p = 0.001, OR = 0.88; 95% CI = 0.82 - 0.95) and low ejection fraction (p = 0.03, OR = 0.20; 95% CI = 0.04 - 0.91) to be independent factors associated with CSCIN. No significant differences were noted between the two groups in patients with hypertension, diabetes and heart failure. Conclusion: CSCIN is a significant concern in high risk groups despite prophylaxis. Patients with lower EF, cerebrovascular disease and low GFR at the time of procedure are more likely to have CIN.