Is Methacholine Challenge Superior to Exhaled Nitric Oxide in the Evaluation of a Cough Variant Asthma? The Attitude Regarding its Management

Abstract

Background: The aim of our study was the follow up of a patient presented only with dry chronic cough:Which is the main diagnostic procedure and the most effective therapeutic approach available for such patients at the first medical visit and during his follow up? Methods: Seventy patients (21 males and 49 females) age of 40, 47 year, presented only with chronic non productive cough were studied. They did accomplish 3 medical controls for a period of 8 months with a distance of 4 months from each other. A detailed history was taken to evaluate the existence of other contributing factors to chronic cough such as: Asthma, GERD, PNDS, and any respiratory infections. Only 65.71% of them accepted to undergo the Methacholline challenge test and the measurement of Exhaled nitric oxid. Results: From 41 patients who at the first visit were considered to have Cough Variant Asthma (CVA), 47.14% resulted to have GERD as a cofactor to cough and 42.86% resulted to have PNDS as a cofactor. The methacolline challenge test resulted to be positive in 89.13% of the patients at the first visit toward 62.85% who resulted positive at the third visit (p<0.05). The value of Exhaled nitric oxid was elevated at the first visit only in 51.28% of the patients toward 50% who had a high level of it at the third visit. Conclusion: and discussion GERD remains still the most frequent cofactor of chronic productive cough as a variant of asthma.

Keywords: Asthma, methacholine, oxid nitric, cough, GERD.