Determinants of response to fluticasone propionate and salmeterol/fluticasone propionate combination in the Gaining Optimal Asthma controL study

BackgroundDuring the Gaining Optimal Asthma controL study, 3416 patients with uncontrolled asthma were randomized to receive salmeterol/fluticasone propionate combination (SFC) or fluticasone propionate (FP) for 1 year. Approximately two thirds of patients achieved well-controlled (WC) asthma, and one third continued to have asthma that was not well controlled (NWC).ObjectiveThis analysis aimed to (1) identify factors influencing treatment response and (2) assess the clinical benefits of SFC and FP in patients with NWC asthma.MethodsLogistic regression analysis was used to investigate whether covariates influenced the achievement of at least WC asthma in the study population. In patients with NWC asthma, predefined criteria were used to assess improvements in 6 clinical outcomes.ResultsFactors affecting the probability of having NWC asthma included smoking status (current vs never: odds ratio [OR], 2.757; 95% CI, 2.061−3.689; P < .0001; former vs never: OR, 1.274; 95% CI, 1.031−1.574; P = 0.0273), sex (women vs men: OR, 0.652; 95% CI, 0.527–0.806; P < .0001), history of inhaled corticosteroid use (no history vs history: OR, 0.546; 95% CI, 0.437−0.683; P < .0001), and treatment (FP vs SFC: OR, 1.972; 95% CI, 1.686–2.308; P < .0001). Of patients with NWC asthma, 86% to 96% showed improvements in 1 or more clinical outcomes.ConclusionIt is imperative for good asthma control that patients stop smoking. Patients who did not have at least WC asthma demonstrated clinical improvements in individual asthma outcomes.Clinical implicationsAlthough not all patients can achieve guideline-defined control, long-term treatment with SFC or FP is associated with clinical improvements in nearly all patients, regardless of smoking history or inhaled corticosteroid use.