title: Effect of gastroesophageal reflux disease on disease severity and characteristics of lung functional changes in patients with asthma.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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. The difference between total airway resistance (TAWR) indicated by resistance at 5 Hz and central airway 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.
  
  
  RESULTS
  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 vital capacity), PEF (peak expiratory flow), and CAWR in these two groups.
  
  
  CONCLUSIONS
  These findings suggest that the severity of asthma as measured by ACT score is not different 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.
authors.affiliation: Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences,Tabriz, Iran.
authors.forename: Akbar
authors.initials: A
authors.lastname: Sharifi
authors.affiliation: Tuberculosis and Lung Disease Research Center, Tabriz University of Medical Sciences,Tabriz, Iran.
authors.forename: Khalil
authors.initials: K
authors.lastname: Ansarin
keywords: Asthma; Gastroesophageal Reflux; Oscillometry; Respiratory Function Tests