The utility of a new therapy, in this instance fluticasone and salmeterol combination (FSC), is determined by multiple uncontrollable factors in individual patients and can be measured by continued use and efficacy over time. Over one year from April 2001, 186 patients with persistent asthma were switched from controller pharmacotherapy to FSC at equidose to prior inhaled corticosteroid. Follow-up data on 171 (92%) indicated 129 (75%) had continued FSC for one year. Compared to the 42 who discontinued FSC, those who continued had significant reduction of asthmatic exacerbations, improved spirometry, and reduced usage of inhaled reliever and systemic corticosteroid.