Analytical approach:
The cost-effectiveness analysis was based on a single clinical study. The time horizon was one year. The authors did not state a study perspective but the health service perspective appeared consistent with the costs included.
Effectiveness data:
The primary effectiveness outcome was incidence of severe asthma exacerbations. A secondary outcome was risk domain asthma control. Data were obtained from a retrospective observational study. Patients using FP-SAL were identified from the UK Optimum Patient Care Research Database. Patients who were switched to efBDP-FOR were matched in a ratio of 1:3 with patients who continued using FP-SAL using several clinical factors: 382 patients were included for efBDP-FOR and 1,146 patients were included for FP-SAL. All variables in the analysis that were statistically significantly different at a level of 10% were included in regression analysis as potential confounders.
Monetary benefit and utility valuations:
Not relevant.
Measure of benefit:
The number of patients who experienced severe exacerbations and the number of patients with risk domain asthma control were used as measures of benefit. Risk domain asthma control was the absence of asthma-related hospital attendance/admission, GP (general practitioner) consultation for lower respiratory tract infection and prescription for acute course of oral steroids.
Cost data:
Costs included asthma-related drug prescriptions, GP consultations and respiratory-related hospitalisation costs. Unit costs for GP consultations were obtained the Unit Costs of Health and Social Care 2011 and assumed an average consultation of 11.7 minutes. Hospital usage costs were obtained from the NHS Reference Costs 2010-2011. Drug prescriptions included inhaled corticosteroids, oral corticosteroids for acute control, short-acting beta2-receptor agonist (SABA), long-acting beta2-receptor agonist (LABA), leukotriene receptor antagonists, theophylline and antibiotics for lower respiratory tract infections. Drug costs were obtained from the British National Formulary.
Analysis of uncertainty:
Uncertainty in the cost-effectiveness estimate was evaluated by using 1,000 replicated bootstrapped samples from the individual patient data. The 1,000 cost and effects estimates were presented on a cost-effectiveness plane.