Objective: To determine the prevalence of factors associated with difficult-to-control asthma. Methods: Patients with severe asthma were selected from the outpatient asthma clinic of the Ribeirão Preto School of Medicine Hospital das Clínicas. The patients were divided into two groups: controlled severe asthma and difficult-to-control severe asthma. After new attempts to optimize the severe asthma treatment, a questionnaire was applied, and additional tests for factors associated with difficult-to-control asthma, such as environmental and occupational exposure, smoking history, social factors, rhinitis/sinusitis, gastroesophageal reflux disease (GERD), obstructive sleep apnea, congestive heart failure (CHF), pulmonary embolism, cystic fibrosis, vocal cord dysfunction, α-1 antitrypsin deficiency, and Churg-Strauss syndrome, were performed. Results: 77 patients with severe asthma were selected, of which 47 suffered from hard-to-control asthma, being 68.1% female, with mean age of 44.4 years (±14.4), and forced expiratory volume in one second of 54.7% (±18.3). The most factors most often associated with difficult-to-control asthma were noncompliance with treatment (68%), rhinitis/sinusitis (57%), GERD (49%), environmental exposure (34%), occupational exposure (17%), smoking history (10%), obstructive sleep apnea (2%), and CHF (2%). At least one of these factors was identified in every case. Conclusions: Noncompliance with treatment was the factor most often associated with difficult-to-control asthma, underscoring the need to investigate comorbidities in the evaluation of patients with this form of the disease.

Keywords: Asthma; Smoking; Gastroesophageal reflux; Patient compliance; Rhinitis; Sinusitis.

Background: The relationship between asthma and gastroesophageal reflux is, as yet, not completely understood. Among the mechanisms thought to be responsible for gastroesophageal reflux-related worsening of asthma symptoms are the vagovagal reflex and microaspiration. Objective: To assess forced expiratory volume in one second after acid infusion. Method: This study investigated the effect of acid infusion in 13 volunteers with moderate asthma and gastroesophageal reflux. Spirometry was performed before and after insertion of an 8F nasogastric tube and a pH meter. After 15 minutes of saline solution infusion into the midpoint between the upper esophageal sphincter and lower esophageal sphincter, and again after 15 minutes of esophageal acidification (with hydrochloric acid) of the same area, forced expiratory volume in one second was reassessed. Acidification was repeated every 5 minutes until forced expiratory volume in one second values stabilized (variation: < 5%). Results: Mean forced expiratory volume in one second values remained stable during the tube insertion, saline infusion, initial hydrochloric acid infusion and subsequent hydrochloric acid infusion procedures (p = 0.72). Lower forced expiratory volume in one second values were seen resulting from the tube insertion in two patients (drops of 11% and 22%, respectively), after saline infusion in another two (drops of 13% and 14%) and after acid infusion in 1 (a drop of 22%). Conclusion: Esophageal acidification over short periods does not lead to spirometric alterations in a group of asthmatics with gastroesophageal reflux. However, in some cases, simple esophageal procedures or infusions result in bronchospasm.

Keywords: Key words: Asthma. Gastroesophageal reflux. Respiratory function tests. Endoscopy/methods.