Renal recovery after severe acute renal failure

Background: There is limited information about renal recovery to independence from renal replacement therapy (RRT) and about factors associated with its occurrence after severe acute renal failure (ARF). Methods: We conducted a population-based surveillance among all adult residents of the Calgary Health Region surviving ICU admission from May 1, 1999 to April 30, 2002. The primary objective was to determine the rate of and the factors associated with 90-day survival and recovery to independence from RRT in critically ill patients with severe ARF. Results: At 90 days, 96 patients (40%) were alive. Of these, 72% were RRT independent with most (87%) requiring < 4 weeks to recover. Prior to RRT, the median (IQR) serum creatinine and mean (SD) serum urea were 395 (252-517) mu mol/L and 29.2 (18) mmol/L, respectively. Oliguria was present in 76%. Intermittent hemodialysis was the initial modality in 46% and continuous renal replacement therapy (CRRT) in 54%. By multivariate analysis, male sex (odds ratio (OR) 7.6, 95% CI, 2.2-27, p = 0.01) and a diagnosis of septic shock (OR 3.9, 95% CI 1.02-14.5, p = 0.05) were associated with an increased odds of recovery. Conversely, a higher Charlson co-morbidity index score (OR 0.71, 95% CI, 0.6-0.85, p = 0.04) and a higher pre-RRT serum creatinine (OR 0.20, 95% CI, 0.05-0.80, p = 0.02, p = 0.02) were associated with reduced odds of recovery. Chronic kidney disease or the initial modality of RRT were not associated with recovery. Conclusions: The majority of severe ARF patients who survive their acute illness are independent of RRT by 90 days. Male sex and a diagnosis of septic shock are independently associated with recovery while a greater co-morbidity score and a higher serum creatinine prior to RRT are predictive of non-recovery.