Risk of chronic dialysis and death following acute kidney injury.

BACKGROUND: Acute kidney injury frequently arises within an acute care hospitalization. Outcomes among acute kidney injury survivors following hospital discharge are poorly documented.

METHODS: We conducted a population-based cohort study between 1996 and 2006 of all adult patients in Ontario with acute kidney injury who did not require in-hospital dialysis, and who survived free of dialysis ≥30 days after discharge. Those with acute kidney injury (n=41,327) were matched 1:1 to patients without acute kidney injury during their index hospitalization. Matching was by age (±1 year), sex, history of chronic kidney disease, receipt of mechanical ventilation during the index hospitalization, and a propensity score for developing acute kidney injury. The primary outcome was subsequent need for chronic dialysis. The secondary outcomes were all-cause mortality and rehospitalization.

RESULTS: Mean age was 70 years, and median follow-up was 2 years (maximum 10 years). The incidence of chronic dialysis was 1.78 per 100 person-years among those with acute kidney injury and 0.74 per 100 person-years among unaffected controls (adjusted hazard ratio [HR]; 2.70, 95% confidence interval [CI], 2.42-3.00). Rates also were higher for all-cause mortality (15.34 vs 14.51 per-100 person-years; adjusted HR 1.10; 95% CI, 1.07-1.13) and rehospitalization (44.93 vs 37.18 per 100 person-years; adjusted HR 1.21; 95% CI, 1.18-1.24).

CONCLUSION: Even when acute dialysis is not required, survivors of acute kidney injury remain at higher risk of receipt of chronic dialysis thereafter. The absolute risk of death was more than 8 times the rate of chronic dialysis.