BACKGROUND: Three fixed maintenance-dose inhaled corticosteroid/long-acting beta(2)-agonist (ICS/LABA) combinations for the treatment of asthma are currently available: salmeterol/fluticasone propionate (Seretide/Advair/Adoair) budesonide/formoterol (Symbicort) and beclometasone/formoterol (Foster). All of these combinations have proven efficacy in terms of controlling symptoms, improving lung function and reducing the rate of exacerbations compared with ICSs and LABAs administered separately. Budesonide/formoterol is also approved for use as maintenance and reliever therapy in a number of countries (Symbicort SMART). Many of the studies supporting the use of budesonide/formoterol combination therapies have included populations of adolescents and adults aged >11 years. OBJECTIVE: This post hoc analysis compared the efficacy of ICS/LABA fixed maintenance-dose treatment with budesonide/formoterol and salmeterol/fluticasone propionate versus budesonide/formoterol maintenance and reliever therapy in patients with persistent asthma aged > or =16 years. METHODS: Following 2-weeks' run-in, 2866 adults aged > or =16 years were randomized to: fixed maintenance-dose budesonide/formoterol 640 microg/18 microg per day, salmeterol/fluticasone propionate 100 microg/500 microg per day plus terbutaline as needed, or budesonide/formoterol 320 microg/9 microg per day plus additional inhalations as needed (budesonide/formoterol maintenance and reliever therapy). Outcome measures included time to first severe asthma exacerbation (primary outcome) and number of severe asthma exacerbations. RESULTS: Budesonide/formoterol maintenance and reliever therapy prolonged time to first severe exacerbation versus budesonide/formoterol and salmeterol/fluticasone propionate fixed maintenance dose (p = 0.037 and p = 0.0089, respectively). Compared with salmeterol/fluticasone propionate fixed maintenance-dose treatment, fixed maintenance-dose budesonide/formoterol reduced the risk of hospitalizations/emergency-room visits by 28% (relative rate [RR] 0.72; 95% CI 0.53, 0.98; p = 0.034) and budesonide/formoterol maintenance and reliever therapy by 37% (RR 0.63; 95% CI 0.46, 0.87; p = 0.0043). All treatments provided similar improvements in lung function, asthma control days and asthma-related quality of life. CONCLUSIONS: Budesonide/formoterol fixed maintenance dose or maintenance and reliever therapy provides similar improvements in current asthma control and reduces the future risk of hospitalizations/emergency-room treatments versus salmeterol/fluticasone propionate fixed maintenance-dose treatment, providing additional clinical benefit to asthma patients aged > or =16 years.