Risk factors and predictive clinical scores for asthma exacerbations in childhood

Abstract

Background: Asthma is a major public health problem that affects millions of children worldwide, and exacerbations account for most of its morbidity and costs. Primary-care providers lack efficient tools to identify children at high risk for exacerbations. We aimed to construct a clinical score to help providers to identify such children.

Methods: Our main outcome was severe asthma exacerbation, which was defined as any hospitalization, urgent visit, or systemic steroid course for asthma in the previous year, in children. A clinical score, consisting of a checklist questionnaire made up of 17 yes-no questions regarding asthma symptoms, use of medications and health-care services, and history, was built and validated in a cross-sectional study of Costa Rican children with asthma. It was then evaluated using data from the Childhood Asthma Management Program (CAMP), a longitudinal trial cohort of North American children.

Results: Compared with children at average risk for an exacerbation in the Costa Rican validation set, the odds of an exacerbation among children in the low-risk (OR, 0.2; 95% CI, 0.1-0.4) and high-risk (OR, 5.4; 95% CI, 1.5-19.2) score categories were significantly reduced and increased, respectively. In CAMP, the hazard ratios for an exacerbation after 1-year follow-up in the low-risk and high-risk groups were 0.6 (95% CI, 0.5-0.7) and 1.9 (95% CI, 1.4-2.4), respectively, with similar results at 2 years.

Conclusions: The proposed Asthma Exacerbation Clinical Score is simple to use and effective at identifying children at high and low risk for asthma exacerbations. The tool can easily be used in primary-care settings.

Figures

Figure 1.

A, Clinical score instructions: One point is assigned for each question answered as yes. The score is calculated by adding all points (total score range, 0-17). For “Doctor visits last year,” one point is assigned for ≥ 3 visits, and one more point (two total) if the patient also had ≥ 6 visits. B, Histogram of total clinical score with superimposed proportion of children who had the Expert Panel Report 3 (EPR-3) outcome (theoretical range, 0-17; actual range, 0-14; mean ± SD, 6.85 ± 2.5; median, 7; interquartile range, 5-8). ROC curve for the total clinical score and the EPR-3 outcome (area under the curve, 0.78 for the exploratory set and 0.76 for the validation set [dashed line]). ROC = receiver operating characteristic.

Figure 2.

Kaplan-Meier curves of time to first exacerbation during 24 months of follow-up in the Childhood Asthma Management Program by score category. A, EPR-3. B, American Thoracic Society/European Respiratory Society. See Figure 1 legend for expansion of the abbreviation.