Background A new asthma therapy containing a combination of the inhaled steroid fluticasone propionate (FLUT) and the long-acting β₂ agonist (LABA) formoterol fumarate (FORM) in a metered-dose inhaler has been developed (FLUT/FORM; flutiform®). In a double-blind, double-dummy, randomised, multicentre, four arm parallel group study, the efficacy and safety of FLUT/FORM vs. FLUT and FORM administered concurrently (FLUT+FORM) was assessed. Here we present efficacy results of a posthoc subgroup analysis comparing FLUT/FORM 500/20 µg vs. FLUT+FORM 500 µg + 24 µg (both twicedaily) by baseline asthma severity.

Methods In total, 620 patients were randomised 1:1:1:1 to receive FLUT/FORM 500/20 µg, FLUT/FORM 100/10 µg, FLUT+FORM 500 µg + 24 µg or FLUT 500 µg. Randomisation was stratified by percentage predicted FEV1 at baseline [≥40– ≤60% (‘severe asthma’; 52% of patients) vs. >60% – ≤80% (‘moderate asthma’; 48% of patients)], allowing a post-hoc dichotomised analysis by baseline FEV1 severity of spirometric and symptom-based endpoints.

Results Similar improvements in lung function (change in pre-dose FEV1 and change in 2-hour post-dose FEV1) were seen in the FLUT/FORM 500/20 µg treatment group and the FLUT+FORM 500 µg + 24 µg treatment group overall [treatment difference 0.079 (95% CI: –0.032, 0.190) P=0.164 and treatment difference 0.040 (95% CI –0.069, 0.149) P=0.471, respectively]. Both severe and moderate asthmatic subgroups demonstrated mean changes from baseline approximating or exceeding a minimally important improvement (200 mL)1 with similar efficacy in the FLUT/FORM 500/20 µg and the FLUT+FORM 500 µg + 24 µg moderate and severe subgroups (Table 1).

There were no statistically significant or clinically relevant differences overall or in either of the subgroups between FLUT/FORM 500/20 µg and FLUT+FORM 500 µg + 24 µg for any symptom-based endpoints. These included asthma symptom scores, sleep disturbance scores, rescue medication use and asthma control days.

Conclusion FLUT/FORM and FLUT+FORM demonstrated similar improvements in lung function (pre-dose and 2hour post dose FEV1) and symptom-based endpoints in the overall population, and in both subgroups.