Chronic hepatitis C virus (HCV) infection may have adverse effects on pulmonary function in patients with chronic obstructive pulmonary disease. This prospective study was designed to determine whether chronic HCV infection affects decline in lung function and airway responses to salbutamol in asthmatic patients.

Interferon ⍺ (6 MIU three times a week for 6 months) was given to 55 HCV-positive asthmatic patients, 18 of whom had a virologic response to interferon. Pre- and postbronchodilator forced expiratory volume in 1 second (FEV₁) and reversibility with salbutamol or oxitropium at years 1, 3, and 6 after interferon therapy were examined.

We found a significant decrease in pre- and postbronchodilator FEV₁ from year 1 to years 3 and 6 only in interferon nonresponders. Reversibility with salbutamol at years 3 and 6 was significantly lower in interferon nonresponders than in HCV-negative patients (P <0.0001) and interferon responders (P <0.0001). Moreover, there was a steep decline in reversibility with salbutamol during the follow-up period only in interferon nonresponders. In contrast, reversibility with oxitropium at years 3 and 6 was significantly higher in interferon nonresponders than in HCV-negative patients and interferon responders, and there was a steep increase in reversibility with oxitropium only in interferon nonresponders. In addition, declines in the diffusing capacity of the lung for carbon monoxide during follow-up were significantly greater in interferon nonresponders than in HCV-negative patients and interferon responders.

Chronic HCV infection is associated with an accelerated decline in lung function and impaired reversibility with salbutamol among asthmatic patients who do not respond to interferon therapy.