Current asthma guidelines are underpinned by evidence derived from randomised controlled trials (RCTs). Although RCT data are considered the gold standard, patients recruited to asthma RCTs are estimated to represent only a small percentage of the real-world asthma population. The poor representation of the asthma population is due to a number of factors, such as tightly-controlled inclusion criteria for RCTs. There is, therefore, a need to carry out real-world observational studies to inform existing guidelines on the effectiveness of available treatments as used in every-day clinical practice in the heterogeneous asthma population.~Asthma management guidelines recommend long-term, daily anti-inflammatory controller therapy to attenuate the chronic airway inflammation of persistent asthma. The choice of inhaled corticosteroid can be guided by practical considerations (e.g., cost factors) as RCTs have so far failed to identify consistent, significant differences in outcomes among the available inhaled corticosteroids, and data from observational studies are lacking.~FP and HFA-BDP are the two main ICS therapies prescribed in the US for the management of asthma. FP is approximately twice as potent and efficacious, on a microgram basis, as BDP. In clinical trials, however, the extra-fine hydrofluoroalkane (HFA) formulation of BDP has demonstrated potency similar to that of FP. This is felt to be because HFA-BDP shows higher and more even lung deposition than FP, with HFA-BDP, unlike FP, having distribution to both large and small airways.~Owing to similarity of effectiveness of extra-fine HFA-BDP and FP suggested by clinical trial data, and the even lung distribution afforded by the smaller HFA aerosol particles, we hypothesises that extra-fine HFA-BDP may be at least as effective as FP in real-world clinical practice. This hypothesis was supported by a retrospective database study of HFA-BDP versus FP using the UK's General Practice Research Database (GPRD). The study found significantly lower odds for achieving the composite proxy measure for asthma control with FP in both patients initiating ICS therapy (0.77, 95%CI 0.61-0.98) and stepping-up ICS therapy (0.82, 95%CI 0.44-1.52) relative to HFA-BDP. The analysis also revealed that FP was prescribed at significantly higher doses than extra-fine HFA-BDP yet had lower associated odds of achieving asthma control.~In addition to significant health benefits, delivering effective asthma control is critical to reducing the substantial economic burden of asthma, with research indicating annual costs are disproportionately attributable to patients with poorly controlled disease. Recent estimates place the annual figure at 56 billion dollars ($) in the US alone, consisting of direct costs and productivity losses.It is therefore of particular importance to consider outcomes achieved in relation to costs incurred when assessing overall benefit of asthma therapies, with a cost-effectiveness analysis of HFA BDP and FP planned as part of the current study.~The aim of this study is to compare the absolute and relative effectiveness and cost-effectiveness of asthma management in patients in the US on inhaled corticosteroid (ICS) maintenance therapy as extra-fine HFA-BDP (Qvar®) pressurised metered dose inhaler (pMDI) compared with fluticasone propionate (FP) pMDI to further examine the findings of the UK study, and to identify similarities or differences in effectiveness and cost-effectiveness outcomes and prescribing practice between the two countries.
This study will compare the absolute and relative effectiveness and cost-effectiveness of asthma management in patients in the USA on inhaled corticosteroid (ICS) maintenance therapy as HFA-BDP (Qvar®) pressurised metered dose inhaler (pMDI) compared with fluticasone propionate (FP) pMDI. .