Association between AKI, Recovery of Renal Function, and Long-Term Outcomes after Hospital Discharge

Background and objectives This study aimed to determine if recovery of kidney function after AKI modifies the association between AM during hospitalization and adverse outcomes after discharge. Design, setting, participants, & measurements The effect of renal recovery after AM was evaluated in a population-based cohort study (n=190,714) with participants identified from a provincial claims registry in Alberta, Canada, between November 1, 2002 and December 31, 2007. AKI was identified by a two-fold increase between prehospital and peak in-hospital serum creatinine (SCr). Recovery was assessed using SCr drawn closest to 90 days after the AM event. All-cause mortality and a combined renal outcome of sustained doubling of SCr or progression to kidney failure were evaluated. Results Overall, 3.7% of the participants (n=7014) had AM, 62.7% of whom (n=4400) survived 90 days. In the 3231 patients in whom recovery could be assessed over a median follow-up of 34 months, 30.8% (n=1268) of AM survivors died and 2.1% (n=85) progressed to kidney failure. Participants who did not recover kidney function had a higher risk for mortality and adverse renal outcomes when AM participants who recovered to within 25% of baseline SCr were used as the reference group (adjusted mortality hazard ratio (HR), 1.26; 95% confidence interval, 1.10, 1.43) (adjusted renal outcomes HR, 4.13; 95% confidence interval, 3.38, 5.04). Mortality HR was notably higher when participants failed to recover within 55% of baseline. Conclusions Renal recovery after AM is associated with a lower risk of death or adverse renal outcomes after hospital discharge. Clin J Am Soc Nephrol 8: 194-202, 2013. doi: 10.2215/CJN.06480612