Natural history and risk stratification of patients undergoing non-invasive ventilation in a non-ICU setting for severe COPD exacerbations

Abstract

Non-invasive ventilation (NIV) delivered in an intensive care unit (ICU) has become the cornerstone in the treatment of patients with severe chronic obstructive pulmonary disease (COPD) exacerbations. A trend towards managing these patients in non-ICU setting has emerged in recent years, although out-of-hospital survival by this approach and how to prognosticate it is unknown. We aimed to investigate these issues. We consecutively recruited 100 patients (49 males; median age 82 years) who received NIV treatment for acute respiratory failure due to COPD exacerbation in non-ICU medical wards of our hospital, between November 2008 and July 2012. We assessed survival (both in-hospital and out-of-hospital) of all these patients, and analyzed baseline parameters in a Cox proportional hazards model to develop a prognostic score. The median survival in the study population was 383 days (240-980). Overall survival rates were 71.0, 65.3, and 52.7 % at 1, 3, and 12 months, respectively. Age >85 years, a history of heart disorders and a neutrophil count ≥10 × 10(9) were associated with higher mortality at Cox's analysis (χ (2) = 35.766, p = 0.0001), and were used to build a prognostic score (NC85). The presence of two or more factors determined the deepest drop in survival (when NC85 ≥2, mortality at 1, 3, and 12 was 60.7, 70.4, and 77.2 %, respectively, while when NC85 = 0 were 4.0, 4.0, and 14.0 %). A simple model, based on three variables (age, neutrophil count and history of heart disease), accurately predicts survival of COPD patients receiving NIV in a non-ICU setting.

Keywords: COPD exacerbations; Non-ICU setting; Non-invasive ventilation; Risk stratification.