Use of C-Reactive Protein in Global Leadership Initiative on Malnutrition (GLIM) Etiologic Criteria for Critically Ill Patients: A Retrospective Claims Database Study

<b>Background/Objectives</b>: The Global Leadership Initiative on Malnutrition (GLIM) is suggested by major societies. The etiologic criteria for inflammation in critically ill patients remain unclear. Because an initial nutritional assessment is recommended within 48 h, it is also possible to use C-reactive protein (CRP) up to 3 days after admission. The purpose of the present study is to explore the utility of CRP in identifying malnutrition and to determine whether a nutritional assessment incorporating CRP criteria can effectively identify malnourished patients in the intensive care unit (ICU). <b>Methods</b>: This was a retrospective cohort study of ICU patients. The primary outcome was a composite of in-hospital mortality, Barthel index < 60 at discharge, and length of hospital stay of 14 days or more. The area under the curve (AUC) for the primary outcome was calculated using CRP between days 0 and 2. We divided the patients into four groups using inflammation criteria with the optimal cut-off and low body mass index (BMI) criteria of the GLIM: CRP+/-, and BMI+/-. <b>Results</b>: A total of 38,981 patients were included. The AUC of the highest CRP between days 0 and 2 was 0.65, which was higher than the CRP on day 0 and the highest CRP between days 0 and 1 (0.59 and 0.63). The AUC and optimal cut-offs varied depending on diagnoses, with a maximum of 0.75 in neurology. The optimal cut-off for the maximum CRP was 3.82 mg/dL. In the four groups of CRP+BMI+, CRP+BMI-, CRP-BMI+, and CRP-BMI-, the in-hospital mortality values were 22.7, 14.4, 10.8, and 4.8% (<i>p</i> < 0.001 between all the groups). <b>Conclusions</b>: In an initial nutritional assessment of critically ill patients, it would be appropriate to use the maximum CRP over 3 days from ICU admission.