Üç-Altı Yaş Arası Çocuklarda Astım Fenotipleri ile Bronşiyal Hiperreaktivite İlişkisi.

Objective: Most of the preschool-age children who have recurrent wheezing episodes are asthmatic and some of them are episodic wheezers. It is not easy to distinguish the asthmatic children among the wheezers based on clinical and laboratory findings. We aimed to differentiate the asthma phenotypes by investigating airway hyperreactivity differences in children between 3-6 years old. Material and Methods: Children who were followed up for recurrent wheezing at the department of Pediatric Allergy and Asthma were included in the study. They were classified as episodic (viral) wheezers and persistent wheezers. Bronchial provocation tests with methacholine and adenosine 5'-monophosphate were performed in both groups. Results: Among the 74 patients, 36.5% (n=27) of the children were episodic and 63.5% (n=47) of the children were persistent wheezers. The number of bronchoconstriction responders to bronchial provocation tests was higher in the persistent wheezers than in the episodic viral wheezers (p<0.001). The methacholine dose that caused a 15% decrease in transcutaneous oxygen pressure (PC15PtcO2) was lower in the persistent wheezers than in the episodic wheezers. The degree of airway hyperresponsiveness was therefore more severe in the persistent wheezers. However, there was no difference between the two groups in terms of the dose of PC15PtcO2 AMP. There was no correlation between the PC15PtcO2 methacholine and PC15PtcO2 AMP in either group. The optimal cut-off to discriminate the episodic and persistent wheezers was 0.24 mg/ml for PC15PtcO2 methacholine by ROC curves, with a sensitivity of 87.2% and a specificity of 55%. The positive likelihood ratio (LR) of PC15PtcO2 methacholine was 1.94, and the negative LR was 0.23. The area under the curve was found to be insignificant for adenosine 5'-monophosphate. Conclusion: Neither direct (methacholine) nor indirect (AMP) challenge tests are capable of discriminating asthma phenotypes in preschoolage children. [ABSTRACT FROM AUTHOR]