Acute renal replacement therapy in critically ill octogenarian or older patients: prognostic factors and renal outcomes

Background The number of octogenarians or older patients admitted to the intensive care unit (ICU) has been growing over the past several years. The aim of this study is to assess factors associated with acute renal replacement therapy (ARRT) requirement in these patients and the impact of this therapy on 90-day mortality. We also aimed to identify prognostic factors associated with mortality risk in the group of patients that required ARRT. Methods Retrospective study of octogenarian or older patients admitted to the ICU at Hospital Clinic de Barcelona from June 2007 to April 2019. Patients on chronic dialysis treatment or with a kidney transplant, and patients with limitation of therapeutic support or admitted for less than 48 h were excluded. Results 217 patients were included in the study, of whom 36.4% required ARRT. Use of vasoactive drugs (VAD) and Sequential Organ Failure Assessment (SOFA) score on admission were higher in ARRT patients (P = 0.009 and < 0.001, respectively). Basal estimated glomerular filtration rate (eGFR) was lower in the ARRT cohort (P < 0.001). Hospital and ICU length of stay were longer in the ARRT cohort (P < 0.001). Ninety-day mortality was 58.2% in the ARRT cohort compared to 55.8% in the non-ARRT control cohort (P = NS). In the survival analysis, only female sex, sepsis and non-renal SOFA >= 6.5 were significantly associated with mortality (P = 0.002, 0.028 and 0.009, respectively) in the ARRT cohort. Conclusion Mortality was not significantly increased in the octogenarian or older population that required and received ARRT compared to control patients who did not require it. Severity scores like SOFA could help in the process of decision making about initiation of ARRT in this population.