Rationale: 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.
Methods: 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.
Results: 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).
Conclusions: 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.