Objective: To evaluate the effect of salmeterol on asthma-specific quality of life in patients experiencing significant nocturnal symptoms.

Design: Randomized, double-blind, placebo-controlled, multicenter clinical trial.

Setting: Allergy/respiratory care clinics.

Patients: Nonsmokers > or = 12 years of age with nocturnal asthma symptoms on at least 6 of 14 days during screening and > or = 15% decrease in peak expiratory flow (PEF) from baseline on nocturnal awakening at least once during screening.

Interventions: Salmeterol, 42 microg, or placebo twice daily. Patients were allowed to continue theophylline, inhaled corticosteroids, and "as-needed" albuterol.

Measurements and results: Outcome measures included Asthma Quality of Life Questionnaire (AQLQ) global and individual domain scores, FEV1, PEF, nighttime awakenings, asthma symptoms, and supplemental albuterol use. Mean change from baseline for the global and domain AQLQ scores was significantly greater (p < or = 0.005) with salmeterol compared with placebo. At week 12, salmeterol significantly (p < 0.001 compared with placebo) increased mean change from baseline in FEV1, morning and evening PEF, percentage of symptom-free days, percentage of nights with no awakenings due to asthma, and the percentage of days and nights with no supplemental albuterol use. Significant improvements in PEF were observed after treatment with salmeterol regardless of concomitant treatment with theophylline (p < 0.05).

Conclusions: These results provide evidence that validates the role of salmeterol in improving quality of life in patients with moderate persistent asthma who exhibited nocturnal asthma symptoms and supports the efficacy of salmeterol compared with that of placebo (ie, "as-needed" albuterol).