The impact of continuous renal replacement therapy on renal outcomes in dialysis-requiring acute kidney injury may be related to the baseline kidney function

BACKGROUND: Many controversies exist regarding the management of dialysis-requiring acute kidney injury (D-AKI). No clear evidence has shown that the choice of dialysis modality can change the survival rate or kidney function recovery of critically ill patients with D-AKI. METHODS: We conducted a retrospective study investigating patients (≥16 years old) admitted to an intensive care unit with D-AKI from 1999 to 2012. We analyzed D-AKI incidence, and outcomes, as well as the most commonly used dialysis modality over time. Outcomes were based on hospital mortality, renal function recovery (estimated glomerular filtration rate-eGFR), and the need for dialysis treatment at hospital discharge. RESULTS: In 1,493 patients with D-AKI, sepsis was the main cause of kidney injury (56.2%). The comparison between the three study periods, (1999–2003, 2004–2008, and 2009–2012) showed an increased in incidence of D-AKI (from 2.56 to 5.17%; p = 0.001), in the APACHE II score (from 20 to 26; p < 0.001), and in the use of continuous renal replacement therapy (CRRT) as initial dialysis modality choice (from 64.2 to 72.2%; p < 0.001). The mortality rate (53.9%) and dialysis dependence at hospital discharge (12.3%) remained unchanged over time. Individuals who recovered renal function (33.8%) showed that those who had initially undergone CRRT had a higher eGFR than those in the intermittent hemodialysis group (54.0 × 46.0 ml/min/1.73 m2, respectively; p = 0.014). In multivariate analysis, type of patient, sepsis-associated AKI and APACHE II score were associated to death. For each additional unit of the APACHE II score, the odds of death increased by 52%. The odds ratio of death for medical patients with sepsis-associated AKI was estimated to be 2.93 (1.81–4.75; p < 0.001). CONCLUSION: Our study showed that the incidence of D-AKI increased with illness severity, and the use of CRRT also increased over time. The improvement in renal outcomes observed in the CRRT group may be related to the better baseline kidney function, especially in the dialysis dependence patients at hospital discharge. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12882-017-0564-z) contains supplementary material, which is available to authorized users.