U-Curve Association between Timing of Renal Replacement Therapy Initiation and In-Hospital Mortality in Postoperative Acute Kidney Injury

Abstract

BackgroundPostoperative acute kidney injury (AKI) is associated with poor outcomes in surgical patients. This study aims to evaluate whether the timing of renal replacement therapy (RRT) initiation affects the in-hospital mortality of patients with postoperative AKI.MethodologyThis multicenter retrospective observational study, which was conducted in the intensive care units (ICUs) in a tertiary hospital (National Taiwan University Hospital) and its branch hospitals in Taiwan between January, 2002, and April, 2009, included adult patients with postoperative AKI who underwent RRT for predefined indications. The demographic data, comorbid diseases, types of surgery and RRT, and the indications for RRT were documented. Patients were categorized according to the period of time between the ICU admission and RRT initiation as the early (EG, ≦1 day), intermediate (IG, 2–3 days), and late (LG, ≧4 days) groups. The in-hospital mortality rate censored at 180 day was defined as the endpoint.ResultsSix hundred forty-eight patients (418 men, mean age 63.0±15.9 years) were enrolled, and 379 patients (58.5%) died during the hospitalization. Both the estimated probability of death and the in-hospital mortality rates of the three groups represented U-curves. According to the Cox proportional hazard method, LG (hazard ratio, 1.527; 95% confidence interval, 1.152–2.024; P = 0.003, compared with IG group), age (1.014; 1.006–1.021), diabetes (1.279; 1.022–1.601; P = 0.031), cirrhosis (2.147; 1.421–3.242), extracorporeal membrane oxygenation support (1.811; 1.391–2.359), initial neurological dysfunction (1.448; 1.107–1.894; P = 0.007), pre-RRT mean arterial pressure (0.988; 0.981–0.995), inotropic equivalent (1.006; 1.001–1.012; P = 0.013), APACHE II scores (1.055; 1.037–1.073), and sepsis (1.939; 1.536–2.449) were independent predictors of the in-hospital mortality (All P<0.001 except otherwise stated).ConclusionsThe current study found a U-curve association between the timing of the RRT initiation after the ICU admission and patients’ in-hospital mortalities, and alerts physicians of certain factors affecting the outcome after the RRT initiation.

Dialysis versus Nondialysis in Patients with AKI

“…Prior studies examining the initiation of dialysis for AKI have not generated consensus (13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Significantly heterogenous, these studies fail to include an adequate nondialyzed control group.…”

Incidence and mortality of postoperative acute kidney injury in non-dialysis patients: comparison between the AKIN and KDIGO criteria

“…The minimal increase of SCr less than 0.5 mL/dL might be regarded as AKI in KDIGO criteria. AKI event is not an accurate predictor of in-hospital mortality for those with AKI less than 3 d. 17,30 In this study, most of the AKI duration were less than 14 d (92.1%) and only 8.9% of the AKI duration were less than 48 h. 27,29,30 As the previous study, the endpoint of the present study was in-hospital mortality censored at 180 d. 17 However, patients might join the hospital for other reasons, especially those with prolonged hospitalization.…”

“…16 All of the included critically ill non-dialysis patients were followed until death or discharge. As previous study, the endpoint of the study is inhospital mortality censored at 180 d. 17 The definitions of AKI are based on the KDIGO and AKIN criteria. 13 The baseline SCr, were defined as the last SCr obtained before admission, and the SCr on ICU admission and within 48 h, the initiation date for AKI and peak AKI were also recorded for KDIGO and AKIN classification.…”

Inter-hospital transfers and outcomes of critically ill patients with severe acute kidney injury: a multicentre cohort study

“…Inter-hospital transfers are associated with potential adverse events and the theoretical risk of clinical instability during transport [11,12]. These factors are compounded by data suggesting that delays in nephrology consultation and RRT initiation in hospitalized patients with AKI are associated with inferior clinical outcomes [3,[13][14][15][16]. Although the controversy surrounding the timing of RRT initiation in AKI generally assumes that RRT is available on-site and that clinician decision-making is the main factor that determines timing of RRT initiation, the lack of RRT capability at many hospitals in Ontario presented a natural setting in which to study the effects of delayed initiation of RRT in the setting of AKI.…”