Background It remains unclear whether contrast-induced nephropathy (CIN) has a prognostic impact on subsequent renal dysfunction and whether deteriorating renal function is a risk factor for CIN. This study aimed to evaluate the occurrence of CIN in patients with pre-existing renal dysfunction and investigate the long-term effects of worsening renal function after coronary angiography or contrast-enhanced computed tomography (CT). The prognostic factors of worsening renal dysfunction were also analyzed.
Methods This was a prospective cohort study of patients at risk for CIN, defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 on coronary angiography or eGFR <45 mL/min/1.73 m2 on contrast-enhanced CT. Serum creatinine levels and the 2-year prognosis were evaluated. CIN was defined as an increase in serum creatinine level by more than 0.5 mg/dL or a 25% increase from the previous value within 72 hours after contrast administration. The primary endpoint was the proportion of patients who had serum Cr doubling or induction of dialysis within 2 years according to CIN occurrence.
Results Of the 410 patients, 19 patients developed CIN (8/142 patients on coronary angiography and 11/268 patients on contrast-enhanced CT), and 38 patients had worsened renal function (21/142 patients on coronary angiography and 17/268 patients on contrast-enhanced CT). CIN was not associated with worsening renal function at 2 years. Analysis by renal function at the time of coronary angiography or contrast-enhanced CT (i.e., eGFR ≥30 ml/min/1.73 m2 and eGFR ≤1.73 m2) found no between-group difference in the occurrence of CIN.
Conclusions CIN is not a prognostic risk factor for the long-term of chronic kidney disease after coronary angiography or contrast-enhanced CT. Pre-existing renal dysfunction is also not a risk factor for CIN, even if the eGFR is <30ml/min/1.73 m2.