Early initiation of continuous renal replacement therapy improves survival of elderly patients with acute kidney injury: a multicenter prospective cohort study

Park et al. Critical Care (2016) 20:260 DOI 10.1186/s13054-016-1437-8 RESEARCH Open Access Early initiation of continuous renal replacement therapy improves survival of elderly patients with acute kidney injury: a multicenter prospective cohort study Jae Yoon Park1, Jung Nam An3,6, Jong Hyun Jhee4, Dong Ki Kim2, Hyung Jung Oh4, Sejoong Kim5, Kwon Wook Joo2, Yun Kyu Oh6, Chun-Soo Lim6, Shin-Wook Kang4, Yon Su Kim2, Jung Tak Park4*† and Jung Pyo Lee6*† Abstract Background: Continuous renal replacement therapy (CRRT) is essential in the management of critically ill patients with acute kidney injury (AKI). However, the optimal timing for initiating CRRT remains controversial, especially in elderly patients. Therefore, we investigated the outcomes of early CRRT initiation in elderly patients with AKI. Methods: A total of 607 patients ≥65 years of age who started CRRT due to AKI between August 2009 and December 2013 were prospectively enrolled. They were divided into two groups based on the median 6-hour urine output immediately before CRRT initiation. Propensity score matching was used to compare the overall survival rate, CRRT duration, and hospitalization duration. Results: The median age of both groups was 73.0 years, and 60 % of the patients were male. The most common cause of AKI was sepsis. In the early CRRT group, the mean arterial pressure was higher, but the prothrombin time and total bilirubin, aspartate aminotransferase, and alanine aminotransferase levels were lower. The overall cumulative survival rate was higher in the early CRRT group (log-rank P < 0.01). Late CRRT initiation was associated with a higher mortality rate than early initiation after adjusting for age, sex, the Charlson comorbidity index, systolic arterial pressure, prothrombin time, the total bilirubin, aspartate aminotransferase, and alanine aminotransferase levels, cumulative fluid balance and diuretic use (hazard ratio, 1.35; 95 % confidence interval 1.06, 1.71, P = 0.02). Following propensity score matching, patient survival was significantly better in the early CRRT group than in the late CRRT group (P < 0.01). The total duration of hospitalization from the start of CRRT was shorter among the survivors when CRRT was started earlier (26.7 versus 39.1 days, P = 0.04). Conclusion: A better prognosis can be expected if CRRT is applied early in the course of AKI in critically ill, elderly patients. Keywords: Elderly patients, Survival, Continuous renal replacement therapy, Acute kidney injury, Propensity score matching * Correspondence: ; † Equal contributors 4 Department of Internal Medicine, College of Medicine, Institute of Kidney Disease Research, Yonsei University, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea 6 Department of Internal Medicine, Seoul National University Boramae Medical Center, 20 Boramae-ro 5-gil, Dongjak-gu, Seoul 07061, Korea Full list of author information is available at the end of the article © 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Park et al. Critical Care (2016) 20:260 Background Elderly people (aged ≥65 years) are currently the fastestgrowing sector of the general population in developed countries. They are more prone to developing acute kidney injury (AKI) because of structural and functional alterations in the kidney [1, 2], comorbidities (e.g., arteriosclerosis, hypertension, diabetes mellitus, and heart failure), and polypharmacy for the treatment of comorbidities, which increase in prevalence with age. Accordingly, an increasing number of elderly patients can be expected to develop AKI [3–5]. For more than a decade, continuous renal replacement therapy (CRRT) has been essential in the management of critically ill patients with AKI [6, 7]. The generally accepted indications for initiating CRRT in AKI include persistent hyperkalemia, severe acidosis and hypervolemia that are unresponsive to adequate medical management, and overt uremic symptoms or signs (e.g., uremic bleeding, pericarditis, and encephalopathy) [8–10]. Although the optimal timing of CRRT initiation remains controversial, recent studies comparing early and late initiation have suggested that early initiation may have a beneficial impact on survival [11–14]. However, elderly patients are more susceptible to hemodynamic complications during dialysis, such as intradialytic hypotension and arrhythmia, because of decreased autonomic function and cardiovascular reserve, bleeding problems, and neurological complications resulting from rapid changes in serum electrolytes and osmolarity [15, 16]. Additionally, because short-term and long-term survival following CRRT are expected to be lower in elderly patients compared with the general population [17], therapeutic decisions, including use of CRRT, tend to be more conservative for patients in this age group, especially in intensive care. Nevertheless, few studies have specifically examined CRRT in older individuals with AKI. Therefore, although previous studies have demonstrated that early initiation of CRRT could be beneficial in the general population, it is not clear whether it could also benefit elderly patients. In the present study, we aimed to investigate the outcomes of early versus late initiation of CRRT using propensity score matching (PSM) in a multicenter, prospective CRRT cohort of elderly individuals. Methods Study population All patients aged ≥18 years who received CRRT for AKI at Seoul National University Hospital, Seoul National University Boramae Hospital, and Yonsei University Severance Hospital were initially screened (n = 1471). The patients were prospectively enrolled between August 2009 and December 2013. We excluded 724 patients who were younger than 65 years of age and 140 who were on Page 2 of 12 chronic dialysis. A total of 607 patients were included in the analyses. They were divided into two groups based on the body-weight-adjusted median 6-h urine output immediately before administration of CRRT. Definitions The definition of AKI was based on the Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guidelines for AKI and was defined as the presence of at least one of the following criteria: an increase in the serum creatinine level ≥0.3 mg/dL (≥26.5 μmol/L) within 48 h; an increase in the serum creatinine level to ≥1.5 times the baseline level that was known or was presumed to have occurred within the previous 7 days; or urine volume <0.5 (...truncated)