Elsevier

Journal of Critical Care

Volume 29, Issue 5, October 2014, Pages 711-717
Journal of Critical Care

Infection/Sepsis
Early reversible acute kidney injury is associated with improved survival in septic shock,☆☆

https://doi.org/10.1016/j.jcrc.2014.04.003Get rights and content

Abstract

Introduction

The fact that acute kidney injury (AKI) is associated with worse clinical outcomes forms the basis of most AKI prognostic scoring systems. However, early reversibility of renal dysfunction in acute illness is not considered in such systems. We sought to determine whether early (≤ 24 hours after shock documentation) reversibility of AKI was independently associated with in-hospital mortality in septic shock.

Methods

Patient information was derived from an international database of septic shock cases from 28 different institutions in Canada, the United States and Saudi Arabia. Data from a final cohort of 5443 patients admitted with septic shock between Jan 1996 and Dec 2009 was analyzed. The following 4 definitions were used in regards to AKI status: (1) reversible AKI = AKI of any RIFLE severity prevalent at shock diagnosis or incident at 6 hours post-diagnosis that reverses by 24 hours, (2) persistent AKI = AKI prevalent at shock diagnosis and persisting during the entire 24 hours post-shock diagnosis, (3) new AKI = AKI incident between 6 and 24 hours post-shock diagnosis, and (4) improved AKI = AKI prevalent at shock diagnosis or incident at 6 hours post followed by improvement of AKI severity across at least one RIFLE category over the first 24 hours. Cox proportional hazards were used to determine the association between AKI status and in-hospital mortality.

Results

During the first 24 hours, reversible AKI occurred in 13.0%, persistent AKI in 54.9%, new AKI in 11.7%, and no AKI in 22.4%. In adjusted analyses, reversible AKI was associated with improved survival (HR, 0.64; 95% CI, 0.53-0.77) compared to no AKI (referent), persistent AKI (HR, 0.99; 95% CI, 0.88-1.11), and new AKI (HR, 1.41; 95% CI, 1.22-1.62). Improved AKI occurred in 19.1% with improvement across any RIFLE category associated with a significant decrease in mortality (HR, 0.53; 95% CI, 0.45-0.63). More rapid antimicrobial administration, lower Acute Physiology and Chronic Health Evaluation II score, lower age, and a smaller number of failed organs (excluding renal) on the day of shock as well as community-acquired infection were independently associated with reversible AKI.

Conclusion

In septic shock, reversible AKI within the first 24 hours of admission confers a survival benefit compared to no, new, or persistent AKI. Prognostic AKI classification schemes should consider integration of early AKI reversibility into the scoring system.

Introduction

Acute kidney injury (AKI) is associated with adverse outcomes, universally increasing mortality, length of hospital stay and the risk of long term chronic kidney disease and kidney failure [1], [2], [3], [4], [5], [6], [7], [8], [9], [10]. In septic shock, AKI is especially common with the risk of worse outcomes increasing with the severity of injury [2], [4], [11], [12], [13], [14], [15], [16].

Current classification schemes for defining AKI, such as the Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) system and the Acute Kidney Injury Network (AKIN) system define the stage and severity of AKI using criteria based on declining urine output and changes in serum creatinine compared to baseline [17], [18], [19], [20], [21]. AKI is then classified according to the most severe stage achieved at any time point, regardless of reversibility. Although this classification has been validated in large international AKI datasets, little is known regarding the impact of earl (≤ 24 hours) reversibility of AKI on outcomes [17], [18], [19]. In this retrospective analysis, we examined the effect of early reversibility of AKI on in-hospital mortality in septic shock.

Section snippets

Study population

The Cooperative Antimicrobial Therapy of Septic Shock (CATSS) database is an international, multicenter database of patients admitted with septic shock to an intensive care unit (ICU). The CATSS database, which has been described in detail previously, uses standardized case definitions and includes repeat serum creatinine measurements during the first 24 hours of admission [13], [22], [23]. The database captures information on consecutive adult (> 18 years old) patients admitted with septic

Results

During the study period, 709 (13.0%) exhibited reversible AKI, 2878 (54.9%) persistent AKI, 635 (11.7%) new AKI and 1221 (22.4%) no AKI. Improved AKI occurred in 1041 (19.1%) individuals. ICU and in-hospital morality occurred in 1851 (34.0%) and 2477 (45.5%), respectively. In hospital mortality occurred in 150 (21.2%) with reversible AKI, 1524 (53.0%) with persistent AKI, 389 (61.3%) with new AKI and 414 (33.9%) with no AKI. Table 1 outlines the study characteristics stratified by AKI status.

Discussion

In this large, international, observational cohort study of patients with septic shock admitted to the ICU, reversibility of AKI was associated with a decreased risk of mortality. Even without complete reversal of AKI, a survival benefit was noted with any improvement in AKI severity. Furthermore independent of AKI classification, individuals with the largest decline in creatinine with the first 24 hours of ICU admission demonstrated a similar survival benefit. These findings suggest that

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    All authors approved of this manuscript.

    ☆☆

    Conflict of Interest Statement: Anand Kumar received unrestricted grant funding from Pfizer, Lilly, Astellas, Bayer, and Merck for the initial development of the CATSS Database. Additional grant funding has been provided by the Manitoba Research Council, the Health Sciences Foundation and the Deacon Foundation. No other author has significant conflict of interest. This specific analysis has not been supported.

    Manish Sood has salary support through the Jindal Research Chair for the Prevention of Kidney Disease at the University of Ottawa.

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