Definitions and Prognoses of Persistent Inflammation, Immunosuppression, and Catabolism Syndrome: A Comparative Analysis via Systematic Review and Observational Study in Japan.

Abstract

To evaluate how heterogeneous diagnostic definitions of persistent inflammation, immunosuppression, and catabolism syndrome (PICS), identified through a systematic review, influence patient identification and associated clinical outcomes when applied to a nationwide Japanese ICU cohort. Systematic review and retrospective cohort study. The multicenter inpatient administrative claims database with laboratory test values in Japan. Critically ill adult patients admitted to ICUs in Japan between March 2010 and September 2021. A total of 215,474 ICU patients were analyzed. None. A systematic review identified 23 clinical studies using varying diagnostic criteria for PICS. Definitions differed substantially in laboratory thresholds, assessment timing, and inclusion requirements. PICS definitions extracted from the review were applied to the Medical Data Vision cohort, and overlap among definitions was assessed using an UpSet plot. The number of patients meeting each definition varied widely (211-47,888 patients), demonstrating that even small differences in thresholds or timing markedly influence patient identification. The prevalence of PICS varied widely across definitions (range, 0.1-22.2%). In-hospital mortality also showed marked variability (range, 11.4-64.0%). Functional outcomes were consistently poor, with a high proportion of patients discharged with a Barthel Index less than 90 (range, 46.5-78.9%) and a prolonged hospital stay greater than 28 days (range, 54.9-94.7%). The present study revealed marked heterogeneity among existing PICS definitions, resulting in wide variations in prevalence and outcomes. Despite this variability, PICS consistently identified patients with prolonged hospitalization and physical impairment. These findings highlight the need for standardized diagnostic criteria to improve comparability across studies and support earlier identification and intervention for at-risk ICU survivors.