Trends in intensive care unit admissions in patients with asthma: a 10-year population-based study

Rationale — Intensive care unit (ICU) admissions are a key marker of asthma severity, and signal patients at highest risk for asthma-related morbidity and mortality. Examining trends in ICU care over time provides invaluable insights into shifts in the severity of asthma exacerbations, and the effectiveness of management strategies at a population level.

Objectives — We aimed to assess trends in ICU admissions and the severity of those admissions over the past 10 years in patients with asthma in Ontario, Canada.

Methods — We assembled a 10-year cross-sectional cohort of individuals with prevalent asthma aged 0-59 years using population-based health administrative databases from 2013-2022. All-cause ICU admissions were identified where asthma or an asthma-related condition was listed as the most responsible diagnosis for hospital admission. Annual asthma admission, ICU admission, invasive ventilation, mortality rates, and average length of stay in hospital were calculated and compared over time. Characteristics of patients admitted to hospital who did and did not require ICU level care were compared.

Main results — From 2013 to 2022, 7,870 ICU admissions occurred among 52,919 patients admitted to hospital with asthma. Over 30% (2685) of these admissions were of children less than 6 years of age. Excluding the COVID pandemic period from 2020-2022, hospital admission rates have been stable. In adults, there was no significant change in ICU admission or invasive ventilation rates (p = 0.45, p = 0.21 respectively), although there was an increase in length of stay in hospital (p < 0.0001). In children less than 18 years of age, there was a significant increase in ICU admission rates (p < 0.0001) but a decrease in length of stay (p = 0.022), with a trend to decreasing invasive ventilation rates (p = 0.073). There was no significant change in in-hospital mortality.

Conclusions — ICU admission rates have not decreased over the last decade. In adults, the severity of these admissions has not improved. Although there has been an increase in ICU admissions in children, hospital stays have been shorter in duration over time with a trend to decreasing invasive ventilation rates.