Association of asthma-like symptoms with AHR
Wheezing was identified in several studies as the most sensitive single symptom for asthma(12, 20) and was also included in many scores developed for the prediction of asthma(24). An interrelation between wheezing associated with colds, AHR and asthma has been reported(19, 25). Likewise, several studies reported that cough, and especially nocturnal cough, is related to severity as well as to a worse prognosis of asthma (26).
Nocturnal cough is highly prevalent in adult patients with asthma(27) and a high frequency of nocturnal cough is shown to be significantly related to the presence of AHR(28). While our findings confirm the importance of wheezing and nocturnal cough as predictors of AHR, Yavuz et al.(7) found that, in spite of a quite similar patient selection, there is neither a significant association of AHR with wheezing nor with nocturnal cough. They observed significance only for the co-existence of nocturnal and exercise-induced cough, a combination with reduced significance in our study.
Several studies have reported a negative association between AHR and dyspnea which might be due to a worse perception of breathlessness(7, 29). The prevalence of dyspnea was also more frequent in children without AHR, however without reaching significance. Nevertheless, findings reported in the literature for single admission symptoms related to AHR and asthma seem to be inconsistent, probably due to a wide variability.