Calorie intake and patient outcomes in severe acute kidney injury: findings from The Randomized Evaluation of Normal vs. Augmented Level of Replacement Therapy (RENAL) study trial

Abstract

Introduction: Current practice in the delivery of caloric intake (DCI) in patients with severe acute kidney injury (AKI) receiving renal replacement therapy (RRT) is unknown. We aimed to describe calorie administration in patients enrolled in the Randomized Evaluation of Normal vs. Augmented Level of Replacement Therapy (RENAL) study and to assess the association between DCI and clinical outcomes.

Methods: We performed a secondary analysis in 1456 patients from the RENAL trial. We measured the dose and evolution of DCI during treatment and analyzed its association with major clinical outcomes using multivariable logistic regression, Cox proportional hazards models, and time adjusted models.

Results: Overall, mean DCI during treatment in ICU was low at only 10.9 ± 9 Kcal/kg/day for non-survivors and 11 ± 9 Kcal/kg/day for survivors. Among patients with a lower DCI (below the median) 334 of 729 (45.8%) had died at 90-days after randomization compared with 316 of 727 (43.3%) patients with a higher DCI (above the median) (P = 0.34). On multivariable logistic regression analysis, mean DCI carried an odds ratio of 0.95 (95% confidence interval (CI): 0.91-1.00; P = 0.06) per 100 Kcal increase for 90-day mortality. DCI was not associated with significant differences in renal replacement (RRT) free days, mechanical ventilation free days, ICU free days and hospital free days. These findings remained essentially unaltered after time adjusted analysis and Cox proportional hazards modeling.

Conclusions: In the RENAL study, mean DCI was low. Within the limits of such low caloric intake, greater DCI was not associated with improved clinical outcomes.

Trial registration: ClinicalTrials.gov number, NCT00221013.

Figure 1

Graphic representation of mean daily caloric intake (DCI) over the first 2 weeks of observation after randomization according to survival status at 90 days.

Figure 2

Kaplan-Meier plots before and after excluding early deaths. (a) Kaplan-Meier graph of survival plots from randomization to day 90 stratified by the delivery of lower (below median) or higher (above median) daily calorie intake (DCI) during the index ICU admission. No P-values are provided as the plot is not adjusted for confounders and is shown to emphasize the reversal of the curve (see Figure 2b) once early deaths are excluded. (b) Kaplan-Meier graph of survival plots from randomization to day 90 stratified by the delivery of lower (below median) or higher (above median) DCI during the index ICU admission, after exclusion of patients who died in the first 96 hrs. No P-values are provided as the plot is not adjusted for confounders and is shown to emphasize the reversal of the curves (see Figure 2a) once early deaths are excluded.