Role of hematological indices and Acute Physiology and Chronic Health Evaluation II score in predicting mortality in critical care patients on high-protein intake

Background Critical illness is characterized by systemic inflammation and muscle wasting, which are associated with poor outcomes. High-protein nutrition has been proposed to mitigate muscle loss, but its impact on hematological indices remains unclear. Objective To evaluate the effects of high-protein nutrition (1.8 g/kg/day) versus standard protein intake (1.2 g/kg/day) and the ability of prognostic inflammatory indices [Prognostic Nutritional Index, Systemic Immune-Inflammation Index (SII), Systemic Inflammation Response Index] and Acute Physiology and Chronic Health Evaluation II (APACHE II) score to predict clinical outcomes in ICU patients. Patients and methods A randomized controlled trial of 84 ICU patients assessed muscle mass via ultrasound, inflammatory markers, and clinical outcomes. Results The high-protein group showed better preservation of quadriceps muscle thickness ( P <0.05 on days 5–14) and lower mortality (16.7 vs. 35.7%, P =0.047). SII predicted mortality with 73.3% sensitivity and 59.3% specificity (area under the curve=0.707, P =0.002), while Prognostic Nutritional Index, Systemic Inflammation Response Index, and APACHE II were nonsignificant. Conclusion High-protein nutrition may improve muscle preservation and survival in ICU patients, with SII emerging as a potential prognostic tool.