Real-world Effectiveness of Combination Therapy in Asthma

Current asthma guidelines in the UK 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 less than 10% of the UK's 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 for more representative RCTs and real-life observational studies to inform existing guidelines and help optimise asthma outcomes.

The fixed combination asthma inhalers FP/SAL (as pMDI and DPI) and BUD/FOR (as DPI) are indicated for use in asthma when adequate asthma control is not achieved with low / medium dose ICS therapy and prn reliever therapy (a short-acting beta-agonist [SABA]). Fixed combination inhalers are also indicated in patients already adequately controlled on separate ICS/LABA therapy. However, emerging trends in asthma prescribing indicate increasing use of add-on therapies (particularly in the form of combination inhalers) in the early stages of asthma therapy, even as first-line therapy.

The British Thoracic Society (BTS) Scottish Intercollegiate Guidelines Network (SIGN) guidelines on the management of asthma advise that there is no difference in efficacy between ICS/LABA therapy given as separate or combined inhalers. However, they do note that, once a patients is on stable therapy, combination inhalers have the advantage of guaranteeing that patients do not take their LABA without their ICS.

In practice, there is significant pressure (supported by asthma guidelines) to use the least expensive, effective inhaled therapies available. While the effect of increased use of combination therapies in terms of patient benefits remains uncertain, the impact on treatment costs for the United Kingdom's (UK's) National Health Service (NHS) is unequivocal and, to date, there are limited data available as to the absolute and relative effectiveness of the ICS/LABA combination therapies currently licensed.

There are a number of inhaler delivery devices available for use in asthma management. Whatever therapy is prescribed, optimal treatment response requires effective drug delivery within the airways; selecting the most appropriate delivery device for an asthma patient, therefore, plays an important role in optimising their asthma control. According to the recent BTS/SIGN guidelines, there is currently no evidence of a clinical difference in the effectiveness of therapy delivery via pMDI ± spacer compared with DPI in either adults or children, and more recent DPIs are rated as effective as older DPIs. Effective use of DPIs and pMDI requires entirely different inhalation techniques and there is some debate as to whether patients prescribed different device types for their reliever and preventer medication (requiring different techniques for each) may have poorer disease control than those prescribed the same device type for both preventer and reliever. Combining aerosols (e.g. pMDI preventer plus BAI reliever) is not considered to cause a problem in this respect.

The aim of this study is to compare the absolute and relative effectiveness of currently licensed ICS/LABA combinations - FP/SAL and BUD/FOR (and their available delivery devices) - in children and adults with asthma whose therapy was changed or increased. Consideration will also be given to the effect of reliever therapy inhaler and the effect of consistency of device used (i.e. same or different devices for preventer and inhaler therapies) on asthma control outcomes. Also to be evaluated are the associated impact of inhaler technique review, recorded inhaler handling problems and use of a spacer in conjunction with a pMDI in terms of achieving asthma control outcomes.

Inclusion criteria

• Aged: 4-80 years: Paediatric cohort (aged 4-11 years); Adult cohort (aged 12-69 years); Elderly cohort (aged 70-80 years.
• Evidence of asthma: i.e. a diagnostic code of asthma or ≥2 prescriptions for asthma at different points in time during the prior year, including one ICS prescription.
• Be on current asthma therapy: i.e. ≥1 asthma prescriptions in the prior year, and at least 1 other asthma prescription during the same period.
• Have at least one year of up-to-standard (UTS) baseline data (prior to the IPD) and at least one year of UTS outcome data (following the IPD).

Exclusion criteria

• Diagnostic read code for chronic respiratory disease (including COPD) at any time
• On maintenance oral steroid therapy at baseline
• Any patients receiving a combination inhaler in addition to their separate ICS inhaler in the baseline year.