Influence of ICU Case-Volume on the Management and Hospital Outcomes of Acute Exacerbations of Chronic Obstructive Pulmonary Disease*

Abstract

To study the relationship between case-volume and the use of noninvasive ventilation during acute exacerbations of chronic obstructive pulmonary disease in ICUs. A 13-year multicenter retrospective cohort study of prospectively collected data. Medical ICUs. From 1998 to 2010, patients with acute exacerbations of chronic obstructive pulmonary disease were identified through a regional database. The characteristics of hospitalization (including the type of mechanical ventilation) and demographic data of the patients were analyzed. ICUs were categorized into tertiles of the running mean annual volume of admissions. A logistic model performed a conditional multivariate analysis of prognostic factors after matching on a propensity score of being admitted to a high-volume unit and on the year of admission. Fourteen thousand four hundred forty acute exacerbations of chronic obstructive pulmonary disease were identified. The Simplified Acute Physiology Score II and ICU mortality increased during the study period (36 to 41 and 12% to 14%, respectively). The proportion of patients receiving any mechanical ventilation support also increased during the study period (from 64% to 86%), with a marked increase in the use of noninvasive ventilation (from 18% to 49%) and a decrease in the use of invasive ventilation (from 34% to 19%). Participating units were distributed into low-volume (< 25 patients per year), medium-volume (26-47 patients per year), and high-volume (> 47 patients per year) tertiles. There was a significant association between case-volume and 1) the proportion of patients receiving noninvasive ventilation (highest vs lowest case-volume tertiles: odds ratio, 1.43 [95% CI, 1.23-1.66]) and 2) lower mortality. Between 1998 and 2010, severity and mortality of acute exacerbations of chronic obstructive pulmonary disease admitted to Collège des Utilisateurs de Données en Réanimation ICUs increased. There was an increasing use of noninvasive ventilation and a decreasing use of invasive ventilation. Use of noninvasive ventilation was related to case-volume, suggesting that increasing experience favors the use of noninvasive ventilation and was associated with a strong trend toward decreased mortality.