Effect of Gastroesophageal Reflux Disease on Disease Severity and Characteristics of Lung Functional Changes in Patients with Asthma

Almost one third of patients with asthma have symptomatic evidence for coexisting gastroesophageal reflux disease (GERD), which is thought to be aggravating factor in asthma at least in some cases. We investigated the impact of coexisting GERD on asthma severity and parameters of lung function. Ninety two asthma patients diagnosed according to ATS criteria were studied. After full history and physical examination, asthma severity was measured in each patient using asthma control test (ACT). GERD symptoms was verified in each patient. Impulse oscillometry(IOS) and lung volume studies (using body-plethysmography and IOS) were performed. Thedifference between total airway resistance (TAWR) indicated by resistance at 5 Hz and centralairway resistance (CAWR) as indicated by resistance at 20 Hz in oscillometry was calculated and considered as representative of resistance at peripheral airways (PAWR). The relationship between the presences of GERD symptoms, ACT score and parameters of lung function were analyzed. PAWR and TAWR were both significantly higher in asthmatic patients with GERD symptoms than patients without GERD symptoms (256.64±161.21 versus 191.68±98.64; P=0.02,and 102.73±122.39 versus 56.76±71.43; P=0.01, respectively). However, no significant difference was noted in mean values of ACT, FEV1 (forced expiratory volume in 1 sec), FVC (forced vitalcapacity), PEF (peak expiratory flow), and CAWR in these two groups. These findings suggest that the severity of asthma as measured by ACT score is notdifferent in patients with and without GERD symptoms. However, total and peripheral airway resistance measured by IOS is significantly higher in asthmatic patients with GERD symptoms.