Purpose: To evaluate the incidence of, risk factors for, and outcome of contrast nephropathy in azotemic diabetic patients undergoing coronary angiography.
Patients and methods: Fifty-nine insulin-dependent diabetics with a mean serum creatinine level of 522 mumol/L (5.9 mg/dL) underwent coronary angiography as part of a pretransplant evaluation. Twenty-four azotemic diabetics undergoing inpatient evaluation not including angiography for transplantation formed the control group. Serum creatinine measurements obtained at baseline and after radiocontrast exposure were compared in patients and control subjects. Risk factors for contrast nephropathy were evaluated in patients with a 25% or greater increase in serum creatinine.
Results: Serum creatinine was significantly elevated 24 hours after radiocontrast exposure in patients (557 +/- 141 mumol/L versus 522 +/- 141 mumol/L, mean +/- SD; p less than 0.001) but not in controls. Seven patients required dialysis within 6 days of coronary angiography and two additional patients required dialysis within 14 days. Contrast nephropathy, defined as a serum creatinine increase of greater than 25% when measured 48 hours after radiocontrast exposure, occurred in 50% of patients and no controls. Univariate analysis of risk factors for contrast nephropathy revealed a significant association with dye quantity (p = 0.002), mean arterial pressure less than 100 mm Hg (p = 0.02), and ejection fraction less than 50% (p = 0.04). Stepwise logistic regression verified the independence of dye quantity and low mean arterial pressure but not low ejection fraction as risk factors for contrast nephropathy. Follow-up serum creatinine values were not significantly different in patients and control subjects.
Conclusions: Azotemic patients with diabetes are at high risk of developing contrast nephropathy even when less than 100 mL of radiocontrast agent is used. The acute renal failure is reversible but precipitates the need for short-term dialysis in some patients. Radiocontrast quantity is an important risk factor not previously noted. The incidence of contrast nephropathy can be minimized by using less than 30 mL of radiocontrast agent.