In children with asthma, following an exercise challenge test (ECT), a difference from baseline of ≥3, indicating worsening symptoms, on a visual analog scale (VAS) rating the level of dyspnea — particularly, when interpreted in conjunction with low scores on the Childhood Asthma Control Test (C-ACT) — was highly effective for the detection and exclusion of exercise-induced bronchoconstriction, according to a study published in the Journal of Asthma.

Despite that exercise-induced bronchoconstriction is a common specific morbidity seen in pediatric asthma and a sign of uncontrolled disease, it is not sufficiently identified by standard self-assessments such as C-ACT, and an additional tool for reporting symptoms is needed that correlates with pulmonary function testing. With few studies having explored the VAS for this purpose in a pediatric population, investigators sought to evaluate the VAS for dyspnea for exercise-induced bronchoconstriction detection in children with asthma on its own and combined with C-ACT scoring.

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Between May 2015 and July 2018, a cross-sectional study enrolled 75 children (mean age, 10.8 years; 70.7% boys) aged 4 to 17 years diagnosed with asthma for comparison of spirometry results before and after an ECT. The ECT was administered according to a standard protocol in a cold dry room. Spirometry was conducted at baseline prior to the ECT and at 1, 3, 6, 9, 12, and 15 minutes post-ECT. A graphic 10 cm VAS for dyspnea was completed by both the children and parents just before exercising and at 3 minutes post-ECT and the difference (ΔVAS) was reported. C-ACT was administered to assess disease control prior to the ECT.

On post-ECT spirometry, a decrease of ≥10% in the forced expiratory volume in 1 second (FEV1) was indicative of exercise-induced bronchoconstriction, while poor asthma control was indicated by a score of ≤19 on the C-ACT. Spearman’s rho (r) was calculated to determine the correlation between ΔVAS and FEV1 reduction, as well as between C-ACT scores and fall in FEV1.

The median fall in FEV1 following the ECT was 14.4%, with 41 (54.7%) children demonstrating evidence of exercise-induced bronchoconstriction. Mean increases in VAS (ΔVAS) for dyspnea postexercise were 3.6 and 2.7 for reports by children and parents, respectively. The mean C-ACT score was 20.3.

Moderate positive correlations were detected between postexercise FEV1 decrease and ΔVAS as reported by both children (r = 0.57; P <.001) and parents (r = 0.58; P <.001). There was no significant correlation found between C-ACT scores and fall in FEV1 (r = -0.23; P =.67).

Using a ΔVAS cutoff of ≥3, the VAS had a sensitivity and specificity for exercise-induced bronchoconstriction of 80% and 79%, respectively, with an area under the curve of 0.82 and a positive predictive value of 82% and a negative predictive value of 77%. For patients who had a ΔVAS ≥3 and/or a C-ACT score ≤19 (n=37), the sensitivity and specificity for exercise-induced bronchoconstriction were 97% and 67%, respectively, while the positive predictive value and negative predictive value were 77% and 96%, respectively.

Study strengths included performance of the ECT according to a standardized protocol and allowance for dissipation of exercise-induced dyspnea prior to post-ECT VAS measurement. Study limitations included observation of the VAS/FEV1 relationship only during ECT administration.

“This study shows that the VAS could be an effective additional tool for diagnosing [exercise-induced bronchoconstriction] in children,” noted the authors. They recommended that future research incorporate additional tools such as heart rate sensors, activity trackers, and hand-held spirometers.

Funding and Conflicts of Interest Disclosures:

There was no funding information provided.

The authors report no conflicts of interest.

Reference

Lammers N, van Hoesel MHT, van der Kamp M, et al. The Visual Analog Scale detects exercise-induced bronchoconstriction in children with asthma [published online September 4, 2019]. J Asthma. doi:10.1080/02770903.2019.1652640