Mortality and Recovery Associated with Kidney Failure due to Acute Kidney Injury

Abstract

Background and objectives: AKI requiring dialysis is a contributor to the growing burden of kidney failure, yet little is known about the frequency and patterns of recovery of AKI and its effect on outcomes in patients on incident dialysis.

Design, setting, participants, & measurements: Using the US Renal Data System, we evaluated a cohort of 1,045,540 patients on incident dialysis from January 1, 2005 to December 31, 2014, retrospectively. We examined the association of kidney failure due to AKI with the outcome of all-cause mortality and the associations of sex and race with kidney recovery.

Results: Mean age was 63±15 years, and 32,598 (3%) patients on incident dialysis had kidney failure due to AKI. Compared with kidney failure due to diabetes mellitus, kidney failure attributed to AKI was associated with a higher mortality in the first 0-3 months following dialysis initiation (adjusted hazard ratio, 1.28; 95% confidence interval, 1.24 to 1.32) and 3-6 months (adjusted hazard ratio, 1.16; 95% confidence interval, 1.11 to 1.20). Of the patients with kidney failure due to AKI, 11,498 (35%) eventually recovered their kidney function, 95% of those within 12 months. Women had a lower likelihood of kidney recovery than men (adjusted hazard ratio, 0.86; 95% confidence interval, 0.83 to 0.90). Compared with whites, blacks (adjusted hazard ratio, 0.68; 95% confidence interval, 0.64 to 0.72), Asians (adjusted hazard ratio, 0.82; 95% confidence interval, 0.69 to 0.96), Hispanics (adjusted hazard ratio, 0.82; 95% confidence interval, 0.76 to 0.89), and Native Americans (adjusted hazard ratio, 0.72; 95% confidence interval, 0.54 to 0.95) had lower likelihoods of kidney recovery.

Conclusions: Kidney failure due to AKI confers a higher risk of mortality in the first 6 months compared with kidney failure due to diabetes or other causes. Recovery within 12 months is common, although less so among women than men and among black, Asian, Hispanic, and Native American patients than white patients.

Keywords: Acute Kidney Injury; Asian Continental Ancestry Group; ESKD; Hispanic Americans; acute renal failure; diabetes mellitus; dialysis; kidney; mortality; race; renal recovery; sex.

Graphical abstract

Figure 1.

Study cohort derivation of 1,045,540 adults who initiated dialysis between January 1, 2005 and December 31, 2014. USRDS, US Renal Data System.

Figure 2.

Kidney failure due to AKI is associated with a higher risk of mortality in the first 6 months following dialysis initiation compared with kidney failure due to diabetes or other causes. Cox proportional hazard models showing hazard ratios for mortality in the kidney failure due to AKI group versus mortality in the diabetes mellitus group, and mortality in the kidney failure due to AKI group versus the mortality in the other group for various postdialysis periods, censored for transplant. (A) Unadjusted hazard ratios and (B) adjusted hazard ratio for all covariates.

Figure 3.

Kaplan-Meier survival estimates for patients show that relative survival probabilities for patients with different kidney failure causes changes across follow-up time. Months from initial dialysis to death, unadjusted and censored for transplant or end of study period, for three cause of kidney failure groups, with numbers of patients at risk.

Figure 4.

Cumulative probabilities for mortality and recovery of kidney function show that recovery is confined primarily to the first 6 months postdialysis initiation. From unadjusted Fine and Gray cumulative incidence model of recovery with censoring for transplant and treating death as a competing risk and from the submodel of mortality with censoring for transplant.