An economic evaluation of adjustable and fixed dosing with budesonide/formoterol via a single inhaler in asthma patients: the ASSURE study

Background: The severity of asthma varies between individuals and over time. As a result individuals may have marked variation in their need for asthma treatment. Adjustable dosing enables patients to assume greater involvement in managing their own condition. Objective: To compare the costs and effectiveness of fixed dosing of budesonide/formoterol (Symbicort Turbohaler*) with adjustable maintenance dosing. Methods: A cost-effectiveness analysis was conducted from the perspective of the UK NHS. Adults with established asthma currently maintained on greater than or equal to 400 mug per day inhaled corticosteroid were enrolled in 365 primary care centres in the UK. Patients were run-in on 2 inhalations twice daily of budesonide/formoterol 80/4.5 mug or budesonide/formoterol 160/4.5 mug (depending on steroid requirement) for 4 weeks and were then randomised to the Symbicort adjustable maintenance dosing plan (SAMD) (n = 782; budesonide/formoterol 1-4 inhalations twice daily depending on symptoms) or Symbicort fixed dosing (n = 771; 2 inhalations twice daily) for a further 12 weeks. The primary effectiveness variable was clinically meaningful change in quality of life (QoL) assessed by the mini-asthma quality of life questionnaire (AQLQ). Secondary effectiveness measures included symptom-free days with no short-acting beta-agonist use. We assessed the costs of study medication, asthma-related concomitant medication, primary care and hospital contacts. Confidence intervals were generated by non-parametric boot-strapping. Results: Clinically meaningful improvement in QoL during the first 4 weeks was reported by 40.8% of enrolled patients. During the following 12 weeks, a net 1% (95% Cl: -4%, 6%) of SAMD patients and 6% (95% Cl: 1%, 10%) of fixed dosing patients reported further improvement. Effectiveness parameters did not differ significantly between groups during the study period. Mean daily cost per patient was pound1.13 (95% Cl: pound1.08, pound1.18) in the SAMD group and pound1.31 (95% Cl: pound1.27, pound1.34) in the fixed dosing. The difference in mean daily cost resulted in an annual per patient cost difference of pound65.70. Adjustable maintenance dosing with budesonide/formoterol provided equivalent QoL to fixed dosing at significantly lower cost.