Long-term outcome of acute tubular necrosis: a contribution to its natural history

As long-term outcome studies of acute renal failure (ARF) are scarce and non-homogeneous, we studied 187 consecutive acute tubular necrosis (ATN) patients without previous nephropathies, discharged alive from our hospital between October 77 and December 92 and followed-up until December 99 (range 7-22 years; median 7.2). Variables were analyzed at the time of the acute episode and during follow-up. In 2000-2001 a clinical evaluation was made in 58 of the 82 patients still alive. Ten patients were lost to follow-up and 95 died. In 59% death was related with the disease present when the ATN developed. Kaplan-Meir survival curve showed 89, 67, 50, and 40% at 1, 5, 10, and 15 years, respectively, after discharge. Survival curves were significantly better (log-rank P<0.001) among the youngest, those surviving a polytrauma, those without comorbidity and surprisingly those treated in intensive care units. The proportional Cox model showed that age (hazard ratio (HR) 1.04 per year of age; P=0.000), presence of comorbid factors (HR 4.29; P=0.006), surgical admission (HR 0.45; P=0.000), and male sex (HR 1.72; P=0.020) were the variables associated with long-term follow-up. In the evaluated patients renal function was normal in 81%. Long-term outcome after ARF depends on absence of co-morbid factors, cause of initial admission and age. Although the late mortality rate is high and related with the original disease, renal function is adequate in most patients.