The relationship between caloric intake and clinical outcomes in critically ill patients: A retrospective study

Background & aims: Despite ongoing research, the optimal nutritional support strategy in the first week of intensive care unit (ICU) stay remains unclear, given the complex interplay of the dynamic metabolic change and evolving nutritional requirements. In this study, we assessed the impact of calorie deficiency during this period on the nutritional care of critically ill patients.

Methods: In this retrospective study, we examined ICU admissions from January 2018 to September 2021, focusing on patients whose ICU stay exceeded 7 days. Data were collected from days 2 to 7 of ICU admission. The "average caloric intake (%)" was calculated as the actual calorie intake divided by the calculated calorie requirement over 6 days. Cox proportional hazard models were employed for analyzing the 28-day mortality, supplemented by sensitivity and subgroup analyses.

Results: The analysis of 3,544 patients revealed that those receiving less than 60% of their target calories in the first ICU week experienced higher 28-day mortality (hazard ratio (HR): 1.41, 95% confidence interval (CI): 1.19-1.67, p < 0.0001). Daily caloric intake below 30% of the goal from day 5 onward was associated with a gradual increase in mortality risk. Conversely, a significant reduction in 28-day mortality was noted in patients with a daily intake of >80% starting from day 6.

Conclusion: Our study underscores the correlation between caloric deficit (< 60%) in the initial ICU week and heightened mortality risk. It suggests the potential benefits of aggressive nutritional intervention toward the end of the week. These insights offer valuable guidance for clinicians in critical care settings.