Impact of Calorie and Protein Deficits on Clinical Outcomes in Critically Ill Patients: Insights from an Indian Intensive Care Unit

Background: Critical illness triggers metabolic alterations, predisposing patients to calorie/protein deficits, which are further exacerbated by nutritional delivery barriers. Nutrition inadequacy is linked to adverse outcomes. Despite guideline recommendations emphasizing early and adequate nutrition support, prescribed calorie and protein targets are frequently not achieved in routine ICU practice, particularly in resource-variable settings. This study evaluates the impact of calorie and protein deficits on clinical outcomes, including mortality and length of stay, among critically ill patients. Methods: This retrospective observational study included 1,073 adult critically ill patients. Nutritional requirements were estimated using ESPEN guidelines. Daily calorie and protein deficits were calculated as difference between prescribed and delivered intake, and cumulative deficits were derived by summing daily deficits over the ICU stay. Patients were stratified into low- and high-deficit groups (<2000 vs. >=2000 kcal; <75 vs. >=75 g protein) . Clinical outcomes were compared using Mann-Whitney U, ?2, and Kaplan-Meier survival analysis, and multivariable logistic regression was performed to identify independent associations with mortality. Results: Calorie deficit >=2000 kcal was associated with longer ICU stay [median (IQR): 10 (7-15) vs. 8 (6-12) days; p<0.001], longer duration of mechanical ventilation [5 (2-9.75) vs. 4 (0-7); p<0.001], and higher mortality (31.3% vs. 22.2%; OR 1.60, 95% CI 1.22-2.11; p=0.001). Protein deficit >=75 g was associated with longer ICU stay [10 (7-14) vs. 9 (6-13) days; p=0.001] and increased duration of mechanical ventilation [5 (2-9) vs. 4 (1-8) days; p=0.014]. Survival was significantly lower in high-deficit groups. Baseline characteristics and severity/nutritional risk scores were comparable, suggesting suggesting an association independent of baseline differences. Conclusions: This study identified critical nutritional deficit thresholds (calorie >=2000 kcal, protein >=75 g) associated with adverse outcomes in critically ill patients. These findings suggest that the impact of nutritional deficits may occur early during ICU stay and at lower thresholds than previously recognized. Given that nutrition represents a modifiable component of ICU care, early, individualized, and protocolized nutritional strategies aimed at minimizing cumulative deficits may help improve clinical outcomes.