Is the ICU a Risk Factor for Future Asthma Readmissions?*
In this issue of Pediatric Critical Care Medicine, Tse and Samson (5) conducted a retrospective analysis of all Canadian children admitted to the hospital with asthma over a 6-year period (2008–2014). The authors used a pan-Canadian inpatient database that had unique identifiers for each child and allowed for tracking of readmissions. Outcomes were compared in two cohorts of children: those admitted to the ICU during their first asthma admission, and those admitted to the ward during their first asthma admission. The authors theorized that children admitted to the ICU during their first asthma admission would have a shorter time to asthma-related readmission. In other words, children admitted to the ICU with a severe asthma exacerbation were more at risk for readmission and potentially represented a more severe asthma phenotype.
The readmission rate in the entire cohort was high; 10% of all children were readmitted at least once during the year following their initial index admission, and 23% were readmitted at least once within 5 years. As hypothesized, children admitted to the ICU during their first asthma admission were significantly more likely to be readmitted within 180 days, 1 year, and 3 years of discharge. Within 1 year, 14% of children admitted to the ICU initially were readmitted, compared with 10% of the children admitted to the ward initially. Within 3 years, 24% of those admitted to the ICU were readmitted, compared with 18% of those admitted to the ward. Interestingly, on bivariate analyses, the authors found that intubation during the initial index hospitalization was a protective factor against readmission, while preschool age was a risk factor for readmission.
Like many good studies, this study (5) raises as many questions as it answers. Is this a distinct phenotype that requires closer attention? Should we monitor and treat this phenotype more closely? Is there anything that we can do to prevent readmission? And, why is intubation protective? Was there an intrinsic characteristic of the kids who were intubated that reduced the risk of readmission? Or was it the way these intubated children were managed post hospitalization? Were kids who were intubated more closely monitored after discharge? Seen by a pulmonologist/allergist? And, does this provide a clue suggesting that it is possible to prevent readmission? Unfortunately, some of the data that may have helped to answer these questions (such as sociodemographic data, referral data, and baseline asthma severity) are not available in this retrospective database. But, these questions provide an excellent jumping-off point for others to study!
Several investigators have examined this population of children with severe asthma exacerbations to try to identify phenotypes that are more at risk for severe exacerbations (6, 7). Maffei et al (7) described a group of children with severe asthma exacerbations who developed rapidly progressive respiratory failure requiring intubation but then also had rapid improvement. However, other investigators have cast doubt on this phenotype by describing that children presenting to a community hospital (rather than a children’s hospital) were more likely to be intubated with acute asthma (7).