Short- and long-term outcomes after non-severe acute kidney injury.

BACKGROUND: Severe acute kidney injury (AKI) is associated with chronic kidney disease (CKD), cardiovascular events and increased mortality. However, little is known about the prognosis in hospitalized population suffering from non-severe AKI episodes. The aim of this study is to determine the impact of non-severe AKI episodes in cardiovascular events, mortality and CKD, on short and long term.

METHODS: Retrospective cohort study to 360 patients who met the criteria for diagnosis of AKI according ADQI guidelines with full recovery of renal function after the AKI episode, admitted between January 2000 and December 2010 in our hospital. Follow-up was 4 years after the diagnosis of AKI. Covariates included demographic variables, baseline creatinine and diagnosis of comorbidities.

RESULTS: 360 AKI survivor patients were included. Twenty five of them (6.7%) had developed CKD after 1-year follow-up. Hypertension (OR 1.62; 95% CI 1.2-2.6, p < 0.05) and serum creatinine >2.6 mg/dL in AKI (OR 1.7; 95% CI 1.2-3.7, p < 0.05) were independent risk factors. After 4-year follow-up, 40 patients (18.3%) had developed CKD; age >66 years was an independent risk factor (OR 1.03, 95% CI 1.03-1.06, p < 0.05). Mortality rate at 4 years was 25.3% and was significantly higher in CKD patients (OR 4.3, 95% CI 1.13-4.90, p < 0.05) and patients >66 years (OR 1.12, 95% CI 1.02-1.06, p < 0.05). The incidence of cardiovascular events also was higher in CKD patients than in non-CKD patients (62.7 vs. 21.7%, p < 0.05).

CONCLUSION: Even after fully recovered non-severe AKI episodes, some patients develop CKD and those have an increase in the incidence of cardiovascular events and long-term mortality.