Temporal Profiles and Clinical Associations of Lipoprotein and Apolipoprotein Profiles in Critically Ill Patients with Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PIICS): A Retrospective Cohort Study

Abstract

Persistent inflammation, immunosuppression, and catabolism syndrome (PIICS) is a severe complication in critically ill patients, accompanied by profound disturbances in lipid metabolism. However, the sequential changes in these lipoproteins and apolipoproteins and their association with ongoing clinical status remain unclear. This study aimed to elucidate the temporal patterns of lipid and apolipoprotein changes and their associations with subsequent day-14-window PIICS adjudication in intensive care unit (ICU) patients. This retrospective study included 262 ICU patients with a length of stay over 14 days, divided into PIICS and non-PIICS groups. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A-I (ApoA-I), and apolipoprotein B (ApoB) were measured on ICU days 1 and 7, and in the day-14 assessment window. Logistic regression and receiver operating characteristic (ROC) analyses were used to assess discriminative ability for subsequent day-14-window PIICS adjudication, and survival was evaluated using Kaplan–Meier curves. PIICS patients had lower TC, LDL-C, and ApoA-I levels at all three timepoints, lower HDL-C on days 7 and 14, and lower ApoB levels on days 1 and 14 compared with non-PIICS patients. On day 7, HDL-C and ApoA-I demonstrated good discriminative ability for subsequent day-14-window PIICS adjudication. Exploratory analyses within the PIICS cohort suggested associations between higher day-14-window levels of these markers and more favorable 90-day survival patterns. Progressive hypolipidemia and hypoapolipoproteinemia, particularly involving HDL-C and ApoA-I, were associated with day-14-window PIICS adjudication, with exploratory associations observed for 90-day survival patterns. These changes may reflect shared inflammatory and metabolic processes rather than acting as independent prognostic markers.