Characteristics and Outcomes of Critically Ill Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease in Australia and New Zealand

Abstract

Rationale: The characteristics and outcomes of patients presenting with an acute exacerbation of chronic obstructive pulmonary disease (AECOPD) requiring Intensive Care Unit (ICU) admission are poorly understood and there is sparse epidemiological data. Objectives: The objectives were to describe epidemiology and outcomes of patients admitted to ICU with COPD and to evaluate whether outcomes varied over time. Methods: We studied adult ICU admissions across Australia and New Zealand between 2005 and 2017 with a diagnosis of AECOPD and used an admission diagnosis of asthma as comparator for trends over time. We measured changes in characteristics and outcomes over time using logistic regression, adjusting for illness severity using the Australian New Zealand Risk of Death (ANZROD) model. Results: We studied 31,991 admissions with AECOPD and 11,096 with asthma. Mean (SD) age for AECOPD patients was 68·3 (11·2) years, with 35·4% mechanically ventilated. For patients with AECOPD the proportion of deaths in ICU was 8·7% and in hospital was 15·4% of admissions, with the proportion of 69·2% discharged home and 5·6% discharged to a high level care facility. During the study period, the proportion of ICU admissions with AECOPD per 10,000 admissions decreased at an annual rate of 2·0 (95% CI 0·8 to 3·2) (p=0·009) but their admission rate per million population increased annually by 4·5 (95% CI 3·7 to 5·3) (p<0·0001). There was a linear reduction in mortality for AECOPD but not for asthma admissions (odds ratio annual decline: AECOPD 0·94 [0·93-0·95] and asthma 1·01 [0·97-1·05]; p=0·001) and an increase in AECOPD admissions discharged to home (odds ratio annual increase: 1·04 [1·03-1·05] vs. 1·01 [0·99-1·03]; p=0·01). The reduction in mortality was sustained after adjusting for illness severity. Conclusions: Across Australia and New Zealand the rate of ICU admissions due to AECOPD is increasing but mortality rates are decreasing, with a corresponding increase in the home discharge rates.