Contrast-induced nephropathy: a prospective analysis of long-term outcome and persistence of renal impairment

Introduction

Despite several prophylactic approaches such as acetylcysteine, theophylline and sodium-bicarbonate, contrast-induced nephropathy (CIN) remains a clinical problem. Regarding the large number of studies on CIN, little is known about long-term follow up of patients with CIN. The aim of our study was therefore to analyse the outcome of patients with CIN included in eight prospective studies on CIN conducted by our group, including more than 1,200 patients.

Methods

A systematic analysis of patients with CIN (defined as increase in serum creatinine ≥ 0.5 mg/dl and/or ≥ 25% within 48 hours after contrast-medium (CM)) using chart review and a telephone call to patients and to physicians involved in therapy after CIN up to 1 year or up to death of the patient. Composite primary endpoint: requirement of renal replacement therapy (RRT), death, persistent increase in creatinine ≥ 0.3 mg/dl as compared with baseline value. Further endpoints: time course of creatinine up to 1 year after CM.

Results

Among 85 cases with CIN, complete datasets sufficient for analysis of the above-mentioned endpoints could be recorded in 55 patients. Thirty-nine male and 16 female patients; age 85.5 ± 13.1 years; amount of CM 274 ± 181 ml; intravenous CM application in 12 patients, intraarterial CM in 43 patients. The 28-day mortality was 8/55 (15%). At least four patients (7.3%) were treated with RRT. A total of 24/55 patients (44%) fulfilled the criteria of the composite endpoint (RRT or death or persistent increase in creatinine ≥ 0.3 mg/dl). Compared with baseline creatinine (1.8 ± 1.2 mg/dl), creatinine levels after 24 hours (2.3 ± 1.2 mg/dl; P < 0.001), 48 hours (2.4 ± 1.4 mg/dl; P < 0.001) and 1 week (2.5 M 1.9 mg/dl; P = 0.033) were significantly elevated. In 37 of the surviving patients, creatinine after 1 year was not significantly higher than before CM (1.65 ± 1.05 vs. 1.46 ± 0.76 mg/dl; P = 0.1). However, patients who died or were on RRT were not included in this comparison. In two of our eight studies CIN was significantly associated with mortality.

Conclusion

Our data indicate that CIN is associated with significant mortality, requirement of RRT and/or persistent renal impairment in nearly one-half of the patients. Since these data were collected in patients included in studies aimed at prophylaxis of CIN, the risk might be even more elevated in clinical routine. Prophylaxis of CIN should therefore be a major issue in patients at risk.