Total reversibility testing as indicator of the clinical efficacy of formoterol in COPD

The Global Initiative for Chronic Obstructive Lung Disease guidelines recommend bronchodilator reversibility testing to guide treatment decisions. This study evaluated the relationship between the change in forced expiratory volume in 1 s (FEV1) with salbutamol or formoterol and the clinical effects of a 4-week formoterol (Foradil) treatment.

At Visit 1, patients (n = 448) with stable chronic obstructive pulmonary disease took an FEV1 reversibility test using 200 microg salbutamol via a metered dose inhaler. At Visit 2 (Day 0), an FEV1 reversibility test was performed using formoterol via a dry-powder inhaler (Aerolizer). Patients then received formoterol 12 microg twice daily until Visit 3 (Day 21-30), when a further formoterol FEV1 reversibility test was performed. Clinical parameters included FEV1, symptom questionnaires and rescue medication use.

There was no significant relationship between the immediate change in FEV1 with salbutamol and the absolute change from baseline in FEV1, symptom scores or rescue medication use after a 4-week formoterol treatment. Relative immediate change in FEV1 with formoterol was correlated with change in rescue medication use (P = 0.02) and FEV1 at Visit 3 (P < 0.001). Total reversibility in FEV1 with formoterol (post-dose Visit 3-pre-dose Visit 2) was correlated with all treatment efficacy variables (P<0.01).

Immediate salbutamol reversibility testing, as performed under these study conditions, failed to predict the clinical efficacy of formoterol. Total reversibility after 4 weeks of formoterol treatment may be a better predictor of clinical benefits of long-term bronchodilator therapy.