# Small airway function in predicting asthma control in preschool children

## TL;DR

This study found that small airway function can predict asthma control in preschool children, with severe airway hyperresponsiveness and lower lung function measures linked to poor outcomes.

## Contribution

The study identifies specific lung function metrics and airway hyperresponsiveness as predictors of short-term asthma control in preschool children.

## Key findings

- Severe airway hyperresponsiveness and decreased FEF50% are significantly associated with poor asthma control in preschool children.
- Preschool children with these risk factors face an elevated risk of poor asthma control in the following 2–3 months.
- Baseline forced expiratory flow measures were significantly lower in children with poor asthma control.

## Abstract

Asthma control in children is often challenging. This retrospective cohort study aimed to investigate the potential contribution of small airway function in predicting asthma control within a 2‐ to 3‐month period following the initial diagnosis in preschool children with asthma. A total of 219 preschool children diagnosed with asthma were enrolled, and their follow‐up was conducted by pediatric pulmonary physicians. Clinical history and lung function results were collected for analysis. To identify risk factors associated with poor asthma control, a multivariable regression model was employed. Sixty‐nine of the patients (31.5%) exhibited poor asthma control. Poor adherence to therapy (14.5% vs. 6.0%, p = 0.038) and the presence of severe airway hyperresponsiveness (AHR) (20.6% vs. 1.6%, p < 0.001) were more prevalent in the group with poor control. Additionally, baseline forced expiratory volume in 1 s in predicting (94.5% vs. 101.4%, p = 0.001), forced expiratory flows (FEF)50% (66.1% vs. 86.0%, p < 0.001), FEF75% (60.9% vs. 75.3%, p = 0.001), and FEF25–75% (70.9% vs. 86.0%, p < 0.001) were significantly lower in the poorly‐controlled group than those of well‐controlled group. There was no significant difference in forced vital capacity in predicting (FVC%) between the two groups (92.4% vs. 96.7%, p = 0.093). Multivariable regression model unveiled initial severe AHR (OR 8.595, 95%CI 1.241–59.537, p = 0.021) and decreased FEF50% (OR 0.971, 95%CI 0.949–0.994, p = 0.012) were significantly associated with short‐term poor asthma control. Preschool children with asthma who exhibites initial severe AHR and/or decreased FEF50% faces an elevated risk of encountering poor asthma control during the subsequent 2–3 months.

This study retrospectively analyzed the clinical history and lung function results to determine risk factors of short‐term poor asthma control. The findings revealed that preschool children with asthma who had severe airway hyperresponsiveness and/or decreased forced expiratory flow at 50% of forced vital capacity predicting (FEF50%) were at risk of poor asthma control in the subsequent 2–3 months.