Dialysis versus Nondialysis in Patients with AKI

Abstract

Background and objectives The benefit of the initiation of dialysis for AKI may differ depending on patient factors, but, because of a lack of robust evidence, the decision to initiate dialysis for AKI remains subjective in many cases. Prior studies examining dialysis initiation for AKI have examined outcomes of dialyzed patients compared with other dialyzed patients with different characteristics. Without an adequate nondialyzed control group, these studies cannot provide information on the benefit of dialysis initiation. To determine which patients would benefit from initiation of dialysis for AKI, a propensity-matched cohort study was performed among a large population of patients with severe AKI.Design, setting, participants, & measurements Adults admitted to one of three acute care hospitals within the University of Pennsylvania Health System from January 1, 2004, to August 31, 2010, who subsequently developed severe AKI were included (n=6119). Of these, 602 received dialysis. Demographic, clinical, and laboratory variables were used to generate a time-varying propensity score representing the daily probability of initiation of dialysis for AKI. Not-yet-dialyzed patients were matched to each dialyzed patient according to day of AKI and propensity score. Proportional hazards analysis was used to compare time to all-cause mortality among dialyzed versus nondialyzed patients across a spectrum of prespecified variables.Results After propensity score matching, covariates were well balanced between the groups, and the overall hazard ratio for death in dialyzed versus nondialyzed patients was 1.01 (95% confidence interval, 0.85 to 1.21; P=0.89). Serum creatinine concentration modified the association between dialysis and survival, with a 20% (95% confidence interval, 9% to 30%) greater survival benefit from dialysis for each 1-mg/dl increase in serum creatinine concentration (P=0.001). This finding persisted after adjustment for markers of disease severity. Dialysis initiation was associated with more benefit than harm at a creatinine concentration$3.8 mg/dl.Conclusions Dialysis was associated with increased survival when initiated in patients with AKI who have a more elevated creatinine level but was associated with increased mortality when initiated in patients with lower creatinine concentrations.

AKI Complications in Critically Ill Patients

“…Two other studies (16,17) demonstrated a similar risk of mortality in patients who did or did not receive RRT after matching patients by propensity analysis scoring. In the most recent study, RRT was associated with a better survival only in patients with a high level of serum creatinine (.4.2 mg/dl) (27), leading the authors to speculate that these findings could be explained by metabolic differences between the patients with low and high creatinine levels. However, these studies did not include all of the AKI complications and urine output as adjusted variables.…”

Patient Selection and Timing of Continuous Renal Replacement Therapy

“…Since the majority of patients with AKI never receive RRT in clinical practice, existing studies and analyses provide insufficient guidance on those who should receive RRT. A recent analysis using propensity matching concluded that patients with AKI only clearly benefitted from RRT if they developed severe azotemia (SCr >4.2 mg/dl) [11] . Clearly this leaves the conundrum that patients who are likely to benefit most from RRT are not easy to identify early at a stage when they may benefit most.…”

A Policy of Preemption

“…Vaara et al use a propensity score-based matching strategy to overcome this limitation, a technique employed by a few other groups, including our own (14,15). While we did not find a benefit to early initiation of dialysis (rather, we found that dialysis was preferable to no dialysis when initiated among those with higher serum creatinine concentrations), we did not use the same definition of "early.…”