PREVALENCE AND CAUSES OF CHRONIC DRY COUGH AT A RESPIRATORY CLINIC IN TRIPOLI

Abstract

Prolonged dry cough, in the absence of other features that suggest common etiologies, can be a diagnostic challenge. The aim of this study was to examine the prevalence and causes of isolated chronic dry cough among the patients who presented to the respiratory clinic in Tripoli Central Hospital during the period from 1 st Jan 2005 to 31st Dec 2009. In this prospective study, data from the patients who met the following inclusion criteria was collected; complaint of isolated dry cough for more than 8 weeks, normal chest radiograph, chest physical examination and basal spirometric values. The post-bronchodilator improvement in the FEV1 was considered significant and suggestive of cough variant asthma if it exceeded 15% of the baseline value. The diagnosis was confirmed if the cough improved or disappeared after a short course of steroid therapy. The diagnosis of reflux associated cough was confirmed if it improved with anti-reflux therapy. The total number of registered patients was 800; 69 consecutive patients (8.6%) met the selection criteria. The mean duration of cough was (± SD) 113 ± 141 weeks (range; 8-720 weeks). Their mean age (± SD) was 32 ± 13.2 years (range; 15-75 yrs). Thirty- nine were females (56.5%), and 8 were current or ex-smokers (11.5%). In 56 patients (81.15%) the likely diagnosis was cough variant asthma (CVA). Out of them; 45 (80%) had associated allergic rhinitis too. All of the CVA patients received a short course of oral steroids in addition to bronchodilator inhalers. In another 7 patients (10.1% of total and mostly males (71.4%)); the likely diagnosis was gastro-esophageal reflux disease (GERD) related cough and they responded to anti-reflux therapy. In the last 6 patients (8.7%) who were male smokers; no clear diagnosis was established. They received bronchodilator therapy and were advised to stop smoking. CVA was highly prevalent cause of chronic cough (81.15%) in the study group. Most of the CVA patients had rhinitis too (80%) and the contribution of post nasal drip to the etiology of cough is difficult to establish. 56.5% of the CVA patients were females and of younger age. GERD related cough was less prevalent (10.1%) and was mostly in males