The prognostic variables predictive of mortality in patients with an exacerbation of COPD admitted to the ICU: an integrative review.

INTRODUCTION Chronic Obstructive Pulmonary Disease (COPD) frequently presents with an acute exacerbation (AECOPD). Debate exists as to whether these patients should be admitted to intensive care units (ICUs). An integrative review was performed to determine whether clinical variables available at the time of ICU admission are predictive of the intermediate-term mortality of patients with an AECOPD. METHODS An integrative review was structured to incorporate a five-stage review framework to facilitate data extraction, analysis and presentation. The quality of the studies contributing to the integrative review was assessed with a novel scoring system developed from previously published data and adapted to this setting. RESULTS The integrative review search strategy identified 28 studies assessing prognostic variables in this setting. Prognostic variables associated with intermediate-term mortality were low Glasgow Coma Scale (GCS) on admission to ICU, cardio-respiratory arrest prior to ICU admission, cardiac dysrhythmia prior to ICU admission, length of hospital stay prior to ICU admission and higher values of acute physiology scoring systems. Premorbid variables such as age, functional capacity, pulmonary function tests, prior hospital or ICU admissions, body mass index and long-term oxygen therapy were not found to be associated with intermediate-term mortality nor was the diagnosis attributed to the cause of the AECOPD. DISCUSSION Variables associated with intermediate-term mortality after AECOPD requiring ICU admission are those variables, which reflect underlying severity of acute illness. Premorbid and diagnostic data have not been shown to be predictive of outcome. A scoring system is proposed to assess studies of prognosis in AECOPD.