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.

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 FEVreduction, 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 FEVdecrease 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.

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

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