Analytical approach:
The study was based on data collected from a single dataset of UK primary care practice records (General Practice Research Database). The analysis was conducted for two different patient populations: one that initiated inhaled corticosteroid therapy and one that was prescribed an increased dose of inhaled corticosteroids. Included patients needed to have been registered at the same practice and had up-to-standard follow-up data for at least 12 months before and 12 months after the index prescription date of the initiation of inhaled corticosteroid therapy or first increase in inhaled corticosteroid dose. The study used 10 years of data and considered outcomes over one year. The authors stated that the perspective was that of the UK NHS.
Effectiveness data:
The effectiveness data came from a single observational study (General Practice Research Database). The analysis was based on an observational database study that identified patients who started or increased inhaled corticosteroid therapy and continued for one year. Potential confounders, which included age, sex, socioeconomic status, comorbid conditions and other treatments, were adjusted for in regression analysis. The sample size was 56,347. The main measure of effectiveness was achievement of control during the outcome year, defined as a composite of no hospital attendance for asthma, no prescription for oral corticosteroids and no lower respiratory tract infection that required antibiotics. An additional measure of control added an additional parameter of daily doses of 200 micrograms (μg) or less of salbutamol or 500μg or less of terbutaline.
Monetary benefit and utility valuations:
Not relevant.
Measure of benefit:
The primary measure of benefit was asthma control.
Cost data:
The analysis included direct medical costs of health care resource use for asthma therapy, consultations, and hospitalisation. The costs were from national resources, such as the British National Formulary, the Personal Social Services Research Unit, NHS reference costs, and the Prescription Cost Analysis for the UK. The price year was 2007. All prices were provided in UK pounds sterling (£). Reflation was conducted, where necessary, and the methods were reported.
Analysis of uncertainty:
The uncertainty around estimates of cost-effectiveness was explored using bootstrapping. The results were presented on a cost-effectiveness plane.