Background: The hypothesis that regular treatment aimed at achieving and maintaining asthma control is accompanied by reduced airway hyper-responsiveness (AHR) was investigated.
Methods: Adult patients (PC(20) methacholine <8 mg/ml, FEV(1)% predicted >or=70%) received salmeterol/fluticasone propionate combination 50/250 microg bd (SFC250) for a 12-week run-in; those achieving well-controlled (WC) asthma were randomised to SFC250 (n = 88) or SFC50/500 microg bd (SFC500) (n = 90) for 24 weeks. AHR (PC(20) methacholine), asthma control, lung function, symptoms, exacerbations and safety were assessed.
Results: During the 12 week run-in (SFC250), a greater than 1 doubling dose increase in PC(20) was observed. During randomised treatment, the increase in AHR was similar, and less than 1 doubling dose, for both groups (adjusted geometric mean PC(20) (mg/mL) at 24 weeks: SFC250: 2.796, SFC500: 2.802; p = 0.992). Compared with SFC250, patients receiving SFC500 had a more rapid improvement in AHR (adjusted mean ratio to baseline respectively at week 4: 1.193 vs. 1.386; week 12: 1.395 vs. 1.672; p = non-significant for both) and showed a greater response to treatment in patients with a low baseline PC(20). Patients maintaining WC asthma were 72 (84%) and 64 (74%) in the SFC250 and SFC500 groups respectively. Both doses of SFC were well tolerated; only four exacerbations were reported, all in the SFC500 group.
Conclusion: Regular treatment with SFC resulted in continuous improvement in AHR with maintenance of asthma control in the majority of patients. SFC500 showed a trend for a more rapid improvement in AHR and resulted in greater improvements in patients with a lower baseline PC(20).
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