Dyspnea is one of the cardinal symptoms of asthma, but it is difficult to be quantified clinically. The modified Borg(mBorg) scale has been successfully used to assess dyspnea in adult, but children may have comprehension difficulties with this scale. The Pediatric Dyspnea Scale(PDS) was adequately designed to measure an asthmatic children’s perception of respiratory symptoms. On the other hand, the fractional exhaled nitric oxide(FeNO) has recently been shown to be a useful marker for inflammation in allergic airway disease. We aimed to assess the validity and clinical efficacy of the PDS and examine the correlation of the PDS with the bronchoconstriction and the value of FeNO.
Methods: We additionally checked the degree of dyspnea when we performed the metacholine challenge test to confirm asthma in 73 children. Before the test, we measured the FeNO value. Serial FEV1 value and dyspnea rating using the mBorg scale and the PDS were recorded during the provocation test. We compared the mBorg scale and the PDS between bronchial hyperresponsiveness positive (BHR(+)) group and BHR negative (BHR(-)) group. We tried to verify the correlation between values of the PDS and the FeNO according to the presence or absence of BHR.
Results: The mBorg scale was correlated well with the PDS (rs=0.880, P<0.001). We found a significant correlation between the percentage decrease in FEV1(ΔFEV1%) and the changes in the dyspnea score (ΔBorg by the mBrog scale, and ΔPDS by the PDS scale) at each step during the metacholine challenge test(mBorg, rs=0336, P<0.001; PDS, rs=0.309, P<0.001). No significant difference in the ΔBorg or ΔPDS, defined as the decrease of dyspnea perception score from baseline at the last step of methacholine challenge test, was observed between the BHR (+) and the BHR (-) group (BHR (+) group, P=0.217; BHR (-) group, P=0.560). We found no significant correlation between the PDS and the value of FeNO in BHR (+) group(rs=0.233, P=0.137) and in BHR (-) group (rs=0.132, P=0.495).
Conclusions: The pediatric dyspnea scale had similar pattern to assess the dyspnea with the modified Borg scale. We found a significant correlation between the percentage decrease in FEV1 and the change of score in dyspnea scale (ΔBorg and ΔPDS) during the metacholine challenge test. However, scores of dyspnea was all the same regardless of the presence of BHR. We did not find a significant correlation between the dyspnea scale and markers of airway inflammation. PDS can only play a supplemental role in predicting the presence of BHR on children with suspected asthma.