Older age, disease severity and co-morbidities independently predict mortality in critically ill patients with COPD exacerbation

Abstract

INTRODUCTION Mechanically ventilated critically ill patients with acute COPD exacerbation (AECOPD) have significantly higher rates of morbidity and mortality compared to patients hospitalized for AECOPD but not requiring ventilatory support. The aim of this study was to describe the characteristics and outcomes of ventilated critically ill AECOPD patients and to identify prognostic variables associated with 28-day ICU mortality. METHODS One hundred and twenty-seven patients admitted to the University respiratory ICU in ‘Sotiria’ Hospital due to AECOPD were retrospectively studied. Data were extracted from the medical records of the ICU database. Demographic features, comorbidities, disease severity, exacerbation rate, and treatment, were recorded along with SOFA and APACHE-II scores and laboratory variables. RESULTS Thirty-five percent of the patients died in the ICU (mean age 73±8 vs 67±8 years in survivors, p<0.001). Non-survivors had significantly more comorbidities compared to survivors (p<0.001), significantly higher APACHE II score (30±7 vs 22±7, p<0.001), and significantly higher rates of multi-organ failure (MOF) (62% vs 10.2%, p<0.001). Independent factors associated with ICU mortality were older age (OR=1.13 per year increase; 95% CI: 1.04–1.22, p=0.004), APACHE II score on admission (OR=1.11 per unit increase; 95% CI: 1.04–1.22, p=0.004), Charlson Comorbidity Index (CCI) (OR=1.79 per unit increase; 95% CI: 1.25–2.55, p=0.001), admission lactate levels (OR=2.60 per mEq/L increase; 95% CI: 1.17-5.80, p=0.019), and COPD severity (OR=4.57; 95% CI: 1.14–18.22, p=0.032). CONCLUSIONS Severe physiological derangement upon ICU admission, COPD disease severity and high co-morbidity burden are predictive factors of 28-day mortality in critically ill AECOPD patients. INTRODUCTION Chronic obstructive pulmonary disease (COPD), a chronic inflammatory disease leading to irreversible airflow limitation, is the third leading cause of death and a substantial source of disability, worldwide1. Acute exacerbations of COPD (AECOPD) contribute at large to the progressive decline in the quality of life and the functional status of these patients2. Moreover, moderate to severe AECOPD may lead to respiratory failure, requiring invasive mechanical ventilation and admission to the intensive care unit (ICU). Critically ill patients with AECOPD admitted to the ICU have significantly higher rates of morbidity and mortality compared to patients hospitalized for AECOPD but not requiring ventilatory support3-7. The severity of the disease per se, the co-existence of multiple co-morbidities, as well as the ICUrelated complications may justify, in part, this fact8-11. Infectious exacerbations or end-stage disease have been identified as major causes of ICU admittance12-14. As yet, many studies have attempted to identify independent predictors of the outcomes of these patients in the ICU, however, the results are not consistent across studies, except for Acute Physiology and Chronic Health Evaluation (APACHE)-II score which seems to have a reproducible effect15-18. The decision for initiating ventilatory support in patients with severe COPD may sometimes become a subject of disagreement among the clinicians that take care of these patients12,18,19. Therefore, the identification of clinical or laboratory characteristics that may predict the outcomes of mechanically ventilated patients with COPD admitted to the ICU for an AECOPD is of importance. The aim of this study was to describe the characteristics and outcomes of patients with infectious AECOPD requiring invasive mechanical ventilation in the ICU of a referral hospital for respiratory diseases. We also sought to identify AFFILIATION 1 1st Department of Respiratory Medicine, School of Medicine, National and Kapodistrian University of Athens and Thoracic Diseases General Hospital Sotiria, Athens, Greece 2 Intensive Care Unit, Thriasio General Hospital of Elefsina, Athens, Greece CORRESPONDENCE TO Nikoletta Rovina. 1st Department of Respiratory Medicine, School of Medicine, National and Kapodistrian University of Athens and Thoracic Diseases General Hospital Sotiria, 152 Mesogeion Avenue, 11527, Athens, Greece. E-mail: nikrovina@ med.uoa.gr