Prognostic value of different laboratory measures of renal function for long-term mortality after contrast media-associated renal impairment.

Background: Contrast media-induced nephropathy (CIN) is associated with markedly increased morbidity and mortality. Although creatinine is at present routinely used to characterize renal function, many studies and guidelines recommend using the estimated glomerular filtration rate (eGFR) since it was found to be much more accurate.

Hypothesis: To assess whether the eGFR or creatinine alone provided a better predictive value for long-term mortality after contrast media-associated renal impairment.

Methods: From a prospective trial with 412 patients undergoing heart catheterization, creatinine and eGFR before and after 24 h, 48-72 h, and 30 d after contrast-media exposure were assessed as well as long-term mortality.

Results: Univariate Cox regression models identified increases in creatinine after 48 h (hazard rate ratio [HRR] 1.754, 95% confidence interval [CI] 1.134-2.712) and 30 d (HRR 3.157, 95% CI 1.968-5.064) as well as decreases in eGFR after 30 d (HRR 0.962, 95% CI 0.939-0.986) to be significant predictors of long-term mortality. However, by multivariable Cox regression, only increases in creatinine after 48 h (HRR 1.608, 95% CI 1.002-2.581) and after 30 d (HRR 2.685, 95% CI 1.598-4.511) turned out to be significant and independent predictors of mortality. With regard to a possibly critical threshold of creatinine increase, our data confirmed the historically grown increase in creatinine of 0.5 mg/dl or more during the first 48 h as being associated with increased mortality (p = 0.016, log rank test).

Conclusions: Serum creatinine, but not eGFR, was predictive for long-term mortality, with a threshold of 0.5 mg/dl or more indicating worse prognosis.