Chronic dialysis and death among survivors of acute kidney injury requiring dialysis.

CONTEXT: Severe acute kidney injury among hospitalized patients often necessitates initiation of short-term dialysis. Little is known about the long-term outcome of those who survive to hospital discharge.

OBJECTIVE: To assess the risk of chronic dialysis and all-cause mortality in individuals who experience an episode of acute kidney injury requiring dialysis.

DESIGN, SETTING, AND PARTICIPANTS: We conducted a population-based cohort study of all adult patients in Ontario, Canada, with acute kidney injury who required in-hospital dialysis and survived free of dialysis for at least 30 days after discharge between July 1, 1996, and December 31, 2006. These individuals were matched with patients without acute kidney injury or dialysis during their index hospitalization. Matching was by age plus or minus 5 years, sex, history of chronic kidney disease, receipt of mechanical ventilation during the index hospitalization, and a propensity score for developing acute kidney injury requiring dialysis. Patients were followed up until March 31, 2007.

MAIN OUTCOME MEASURES: The primary end point was the need for chronic dialysis and the secondary outcome was all-cause mortality.

RESULTS: We identified 3769 adults with acute kidney injury requiring in-hospital dialysis and 13 598 matched controls. The mean age was 62 years and median follow-up was 3 years. The incidence rate of chronic dialysis was 2.63 per 100 person-years among individuals with acute kidney injury requiring dialysis, and 0.91 per 100 person-years among control participants (adjusted hazard ratio, 3.23; 95% confidence interval, 2.70-3.86). All-cause mortality rates were 10.10 and 10.85 per 100 person-years, respectively (adjusted hazard ratio, 0.95; 95% confidence interval, 0.89-1.02).

CONCLUSIONS: Acute kidney injury necessitating in-hospital dialysis was associated with an increased risk of chronic dialysis but not all-cause mortality.