Association Between Dynamic Prealbumin Trajectories and Prognosis in Critically Ill Patients

Elevated prealbumin is a good predictor of positive nitrogen balance. Compared to albumin's half-life of 19-21 days, prealbumin is advantageous in assessing short-term nutritional changes and has been widely recognized as a biomarker for nutritional status and recovery of eating ability. However, prealbumin levels vary considerably depending on patient characteristics, degree of inflammation, and stage of critical illness. In acute inflammation, infection, or trauma, prealbumin concentrations decrease due to various factors, including cytokine-induced downregulation of synthesis, extravasation into the vascular system, blood dilution, and increased consumption. Multiple studies have shown that prealbumin is associated with poor prognosis.

Furthermore, the short half-life of prealbumin means that in the acute phase, PAB levels fluctuate over time. The trajectory of PAB level changes, rather than a single point, may provide a promising approach for dynamically assessing the adequacy and effectiveness of nutritional support in malnourished patients. This could help researchers more accurately describe and understand the heterogeneity and similarities within and between individual patients. Therefore, its dynamic changes may better reflect the severity of the patient's condition and the recovery of nutritional status. Previous studies have shown that for critically ill trauma patients, lower-than-normal total respiratory rate (TTR) levels upon admission are independently associated with poorer prognosis, while increased TTR levels over time are associated with better prognosis. Other studies have indicated that for every unit increase in CRP, TTR decreases by 0.024 units. This means that a 0.024-unit increase in CRP followed by a TTR decrease of more than 1 unit may be due to ineffective nutritional support. However, some researchers argue that prealbumin and the effectiveness of nutritional support are not related to outcome.

Therefore, changes in prealbumin levels in the early stages of critical illness pose a diagnostic challenge in distinguishing between the resolution of inflammation, the adequacy of nutritional support, and the shift towards anabolism.

This is an observational clinical study that will be conducted strictly in accordance with the STROBE guidelines. The first phase will utilize database analysis to track the dynamic trends of prealbumin levels, revealing the relationship between different trajectories and nutritional status and patient prognosis. The second phase will prospectively validate this study using similar patients treated at the Intensive Care Unit of Jilin University First Hospital, aiming to clarify the potential value of prealbumin in nutritional support and prognosis for critically ill patients.

• In-hospital mortality [Time frame: From ICU admission (Day 1) through hospital discharge or death, whichever occurs first (up to 28 days).]
• ICU-acquired infection [Time frame: From ICU admission (Day 1) through ICU discharge or death, whichever occurs first (up to 28 days).]
• ICU length of stay [Time frame: From ICU admission (Day 1) through ICU discharge or death, whichever occurs first (up to 28 days).]
• Ventilator-free days through Day 28 [Time frame: 28 days after ICU admission]
• Vasopressor-free days during ICU stay [Time frame: From ICU admission (Day 1) through ICU discharge or death, whichever occurs first (up to 28 days).]
• Survival time up to Day 28 [Time frame: 28 days after ICU admission]
• Energy/Protein intake (weight-adjusted) [Time frame: Days 1-14 after ICU admission.]
• Longitudinal IL-6 levels during ICU Days 1-14 [Time frame: During the first 14 days after ICU admission (ICU days 1-14).]
• Longitudinal change in albumin during ICU Days 1-14 [Time frame: During the first 14 days after ICU admission (ICU days 1-14).]
• Longitudinal change in CRP during ICU Days 1-14 [Time frame: During the first 14 days after ICU admission (ICU days 1-14).]
• Longitudinal lymphocyte count during ICU Days 1-14 [Time frame: During the first 14 days after ICU admission (ICU days 1-14).]
• Longitudinal change in White blood cell count during ICU Days 1-14 [Time frame: During the first 14 days after ICU admission (ICU days 1-14).]