Post‐intensive care syndrome after critical illness: incidence and predictors in a nationwide cohort

INTRODUCTION: As survival rates after critical illness improve, increasing numbers of ICU survivors experience post-intensive care syndrome (PICS), with physical, cognitive and psychiatric impairments. However, there is a lack of robust population-level estimates on incidence rates to guide the implementation of measures to address this issue. METHODS: We conducted a retrospective nationwide cohort study using the South Korean National Health Insurance Service database. Adults admitted to any ICU who were alive ≥ 12 months after hospital discharge were included. To estimate the incidence of PICS, we did not include patients with any PICS-related diagnosis in the year before the index ICU admission. Post-intensive care syndrome was defined as a new diagnosis in at least one domain - physical, cognitive or psychiatric - within 12 months of hospital discharge. RESULTS: Among 234,069 ICU survivors with no prior PICS diagnosis, 130,110 (55.6%) developed PICS within 12 months of hospital discharge. Risk factors included older age (odds ratio (OR) 1.01, 95%CI 1.01-1.01); female sex (OR 1.17, 95%CI 1.15-1.19); lower income, particularly among Medical Aid beneficiaries (OR 1.16, 95%CI 1.12-1.21); pre-existing disability (mild-to-moderate: OR 1.12; 95%CI 1.09-1.15; severe: OR 1.08, 95%CI 1.05-1.12); higher comorbidity burden such as cerebrovascular disease (OR 1.88, 95%CI 1.84-1.92), dementia (OR 3.11, 95%CI 2.91-3.31) or chronic pulmonary disease (OR 1.25, 95%CI 1.22-1.28); and exposure to mechanical ventilation (OR 1.40, 95%CI, 1.36-1.44) or continuous renal replacement therapy (OR 1.12, 95%CI 1.05-1.12). DISCUSSION: In a nationwide cohort of 234,069 ICU survivors, over half developed PICS within 12 months, with physical impairment most common. These findings quantify the survivorship burden attributable to critical illness and underpin the need for structured, multidisciplinary follow-up and rehabilitation for high-risk groups.