Hacettepe Üniversitesi İç Hastalıkları Yoğun Bakım Ünitesinde İzlenen Hastalarda Kronik Kritik Hastalık Ve Persistan İnflamasyon İmmünsüpresyon Ve Katabolizma Sendromu Prevalansının Araştırılması

Abstract

Advances in intensive care have increased survival from the acute phase of critical illness. However, this has also led to a large and growing population of chronically ill patients who remain dependent on prolonged mechanical ventilation (MV) and other intensive care therapies, requiring multiple organ support. This condition, termed chronic critical illness (CCI), imposes a substantial burden on health systems (1). There is no universally accepted definition of CCI in the literature. Our study aimed to compare the prevalence and patient characteristics according to four commonly used CCI definitions among patients admitted to the Internal Medicine Intensive Care Unit at Hacettepe University. We also examined the characteristics of patients with Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PIICS), a subgroup within CCI. Between 10/01/2023 and 03/31/2025, of 1,074 patients admitted to the Internal Medicine ICU, 823 were included after excluding inter-hospital transfers (n=22) and readmissions (n=229). Patients were evaluated according to four previously defined CCI definitions and CCI prevalence rates were determined. The four CCI definitions were as follows: CCI-1: need for MV (≥6 hours/day) for ≥21 days (2); CCI-2: requirement for MV for 14–21 days or longer, or tracheostomy (3); CCI-3: ICU length of stay ≥8 days with at least one of the following: MV (≥96 hours in a single episode), tracheostomy, stroke, head trauma, sepsis, or major trauma (4); CCI-4: ICU stay ≥14 days and, on day 14, cardiovascular SOFA score ≥1 and/or other component scores ≥2 (5). PIICS diagnostic criteria: ICU length of stay ≥14 days; CRP >150 μg/dL; total lymphocyte count <0,80 ×10⁹/L; serum albumin <3,0 g/dL; prealbumin <10 mg/dL; creatinine increase index <80% (6). Of the 823 included patients, 460 (55.89%) were male. The median age was 67 years (IQR 54–77). CCI prevalence was: CCI-1, 5.47% (n=45); CCI-2, 9.36% (n=77); CCI-3, 24.18% (n=199); and CCI-4, 19.68% (n=162). PIICS prevalence was 8.26% (n=68). Among patients meeting CCI-4 criteria, the prevalence of PIICS was 41.97%. In multivariable and machine-learning analyses, the prominent parameters for CCI-3, CCI-4, and PIICS included APACHE II score, SOFA, endotracheal intubation within the first 24 hours, presence of neurological disease, hypoalbuminemia, CRP/procalcitonin, BUN/creatinine, PaCO₂, and elevated lactate. This study is the first to prospectively compare CCI definitions and prevalence and to evaluate PIICS prevalence in a medical ICU. The finding that different definitions yield different prevalence rates highlights the need for an ideal, easily applicable definition of CCI and underscores the necessity for further research focusing on PIICS.