All patients were recruited from asthma clinics in a primary care practice (Table 1). Accurately interpreted spirometry in primary care at asthma and COPD in clinics – https://onlineasthmainhalers.com/spirometry-can-be-done-in-family-physicians-offices-and-alters-clinical-decisions-in-management-of-asthma-and-copd.html. Patients had been receiving a stable dose of inhaled steroids for at least 2 months. All patients used short-acting P-agonists as needed, and 26 of 50 patients were also receiving a long-acting p2-agonist. After an initial visit and baseline measurements, all patients received 4 weeks of treatment with montelukast (10-mg tablet daily). A control group included 13 age-matched, healthy subjects with no history of asthma or atopy, no respiratory infection for at least 6 weeks prior to testing, and no current medications. The study was approved by the ethics committees of the Royal Brompton Hospital and West Kent Health Authority, and written consent was obtained from all patients.
Study Design
The study consisted of four visits: an initial assessment, after 2 weeks and 4 weeks of active treatment with montelukast, and 2 weeks after discontinuation of treatment. At each visit, the patients underwent spirometry and completed an AQL questionnaire, and exhaled NO and EBC were measured.
Measurements
Spirometry was performed with a dry spirometer (Vitalograph; Buckingham, UK). Exhaled NO was measured using an NO analyzer (NIOX; Aerocrine; Stockholm, Sweden). EBC was collected by condenser (EcoScreen; Jaeger; Wurzburg, Germany). Patients were asked to breath tidally for a period of 8 min. Condensate samples were transferred on dry ice and stored at — 70°C until analyzed. Cys-LTs (leukotriene C4, leukotriene D, and leukotriene E4) and LTB4 concentrations were measured with a specific enzyme immunoassay (Cayman Chemicals; Ann Arbor, MI). The lower limit of detection for these assays was 4.0 pg/mL for cys-LTs and 4.4 pg/mL for LTB4. An AQL was used to assess subjective improvement.
Statistical Analysis
Data were expressed as means ± SEM. For comparison between groups, a nonparametric Mann-Whitney U test was used. Significance was defined as a value of p < 0.05. Correlations were evaluated by nonparametric Spearman test. Results were considered significant at a value of p < 0.05.
Table 1—Patient Characteristics
| Characteristics | No Asthma | Asthma |
| Patients. | 13 | 50 |
| Age, yr | 50 ± 5 | 53 ± 2 |
| Male/female gender | 5/8 | 30/20 |
| FEVj, % predicted | 101 ± 4.1 | 69 ± 3.4 |
| FVC, % predicted | 99 ± 2.1 | 80 ± 3.0 |
| Inhaled steroids, ^g/d | 0 | 759 ± 56 |