Association between organ dysfunction during ICU stay and post-intensive care syndrome at 1 year after ICU discharge: a prospective cohort study

BACKGROUND: Post-Intensive Care Syndrome (PICS) affects a substantial proportion of intensive care unit (ICU) survivors. This study investigates whether granular features of the ICU course including organ dysfunction are associated with the prevalence of PICS one year after ICU discharge. METHODS: This was a prospective single-center cohort study of 159 adult surgical ICU survivors enrolled between September 2023 and August 2024. Standardized assessments for PICS domains were performed at 3 and 12 months; PICS was defined a priori as impairment in ≥ 2 of 3 domains (physical, cognitive, psychological). ICU exposure data were ascertained retrospectively from electronic health records. We compared baseline, illness severity and ICU-course variables between patients with and without PICS at 12 months. The primary exposure was the burden of critical illness, operationalized as the sum of organ dysfunctions during the ICU stay. Discriminative ability was evaluated across the organ dysfunction count model, a data-driven three-variable model as well as baseline-only and severity-score models as comparators. RESULTS: At 12 months, 49 of 159 patients (31%) met PICS criteria. Baseline demographics and comorbidities did not differ between groups. Patients with PICS had longer and more complicated ICU stays, and more organ dysfunctions. Each additional organ dysfunction was associated with significantly higher odds of PICS (odds ratio [OR] 2.91; bias-corrected and accelerated [BCa] bootstrap 95% CI 1.92-6.00; p < 0.001). The organ dysfunction count demonstrated good discrimination (area under the receiver operating characteristic curve [AUC] 0.83; 95% CI 0.75-0.91; optimism-corrected AUC 0.82), significantly exceeding a baseline-only model containing demographics and comorbidities (AUC 0.60; 95% CI 0.50-0.71; DeLong p < 0.001), as well as outperforming admission Sequential Organ Failure Assessment (SOFA, AUC 0.63), and Acute Physiology And Chronic Health Evaluation II (APACHE II, AUC 0.64) models. An exploratory, data-driven three-variable model yielded an apparent AUC of 0.87 (optimism-corrected 0.83) with borderline calibration. CONCLUSIONS: In this exploratory analysis, the breadth of organ system involvement during critical illness, captured by the number of organ dysfunctions, was more strongly associated with PICS at 12 months after ICU discharge and demonstrated greater discriminative ability than any baseline demographics or comorbidities as well as SOFA and APACHE scores. These findings are hypothesis-generating and require external validation before clinical application.