Study objectives: The interaction between chronic hepatitis C virus (HCV) infection and bronchial asthma is of considerable interest. This study was designed to examine whether differences in airway responses to an inhaled anticholinergic agent exist between asthmatic patients with and without active HCV infection.
Design: Controlled cross-sectional analysis.
Setting: University hospital.
Patients: Sixteen HCV-negative asthmatic patients and 36 HCV-positive asthmatic patients.
Interventions: All HCV-positive patients received interferon (INF) therapy for 6 months (INF responders, 16 patients; INF nonresponders, 20 patients). No patient had received INF within 3 years of the start of the study.
Measurements and results: Airway hyperreactivity to methacholine (ie, the provocative concentration of methacholine causing a 20% fall in FEV1 [PC20]), maximal increase in FEV1, and forced expiratory flow between 25% and 75% of FVC (FEF25–75) after the administration of oxitropium bromide (200 μg) were examined. At the start of the study, the groups were well-matched with respect to age, body mass index, and baseline lung function, including methacholine PC20. The mean (SD) increase in FEV1 after oxitropium bromide administration was significantly greater in patients with active HCV (95  mL) than in HCV-negative asthmatic patients (68  mL) and asthmatic patients with inactive HCV infection (69  mL; p < 0.001). The increase in FEF25–75 after oxitropium bromide administration was also significantly greater (250  mL/s vs 170  and 180  mL/s, respectively; p < 0.029).
Conclusions: In patients with asthma, active HCV infection is associated with increased bronchodilator responses to inhaled oxitropium bromide. HCV infection may modulate acetylcholine-mediated airway tone.