Background: Acute tubular necrosis (ATN) is the most common type of acute renal failure in hospitalized patients and is associated with a high morbidity and mortality. The cause of ATN can be divided into nephrotoxic, ischemic, or mixed.
Objective: To test the hypothesis that the cause of ATN affects its clinical outcome.
Methods: The study compares clinical outcomes of patients enrolled in the placebo arm of a multicenter, randomized, double-blinded, placebo-controlled trial of anaritide (Auriculin, synthetic atrial natriuretic peptide, Scios, Mountain View, Calif) in patients with well-defined ATN. Patients were divided prospectively into groups according to the cause of ATN: pure nephrotoxic, pure ischemic, or mixed nephrotoxic and ischemic. Outcomes of interest were dialysis-free survival and all-cause mortality on day 14 and day 21. The causal groups were compared with respect to the prevalence of several comorbidities suspected of affecting the clinical outcomes.
Results: Mortality was 10% in the nephrotoxic group and 30% in the ischemic group on day 21. Dialysis-free survival was 66% in the nephrotoxic group and 41% in the ischemic group on day 21. Outcomes in the mixed and ischemic groups were similar. Compared with the nephrotoxic group, there was a significantly higher prevalence of cardiogenic shock, hypotension, sepsis, and respiratory failure and a tendency toward a higher prevalence of acute hepatic dysfunction in the ischemic group. Diabetes mellitus was more prevalent in the nephrotoxic group. Among patients with ischemic ATN, dialysis-free survival improved significantly and mortality tended to decline with advancing age.
Conclusions: Among patients with ATN, those in whom renal ischemia was causative had significantly higher mortality and lower dialysis-free survival than those whose ATN was purely nephrotoxic in origin. This difference in clinical outcomes was associated with a higher prevalence of serious commorbidities in the ischemic ATN group. Advancing age was associated with improved dialysis-free survival and a tendency toward reduced mortality in patients with ischemic ATN.