Real-world Effectiveness of Qvar Versus FP, a US Study (USQvarAsthma)

• Proxy Asthma Control [ Time Frame: One-year outcome period ] [ Designated as safety issue: No ]
  1. No recorded hospital attendance for asthma, including admission, Emergency Room (ER) attendance or Out-Patient Department (OPD) attendance, AND
  2. No prescriptions for acute courses of oral steroids, AND
  3. No GP consultations, hospital admissions or ER attendance for lower respiratory tract infections (LRTI) requiring antibiotics.
  
  
• Total number of asthma exacerbations and exacerbation rate ratio [ Time Frame: One-year outcome period ] [ Designated as safety issue: No ]

  Where exacerbations are defined as an occurrence of:

  1. Unscheduled hospital admissions / Emergency Room attendance for asthma, OR
  2. Use of acute courses of oral steroids
  
  
• Revised proxy asthma control [ Time Frame: One-year outcome period ] [ Designated as safety issue: No ]

  No recorded hospital attendance for asthma, including admission, Emergency Room (ER) attendance, out-of-hours attendance, or Out-Patient Department (OPD) attendance, AND No prescriptions for acute courses of oral steroids, AND No GP consultations, hospital admissions or ER attendance for lower respiratory tract infections (LRTI) requiring antibiotics.

  Average daily, prescribed dose of ≤180mcg salbutamol / albuterol or ≤500mcg terbutaline

  
  

• Asthma control plus no additional or change in therapy [ Time Frame: One-year outcome period ] [ Designated as safety issue: No ]

  Success: defined as the absence of

  1. Exacerbation:

     1. Unscheduled hospital admissions / ER attendance for asthma, OR
     2. Acute use of oral steroids

     AND

  2. No consultations, hospital admissions or ER attendance for lower respiratory tract infections (LRTI) requiring antibiotics§

     AND

  3. No change in therapeutic regimen:

     1. Increased dose of ICS, and/or
     2. Change in ICS and/or
     3. Change in delivery device, and/or
     4. Use of additional therapy as defined by: long-acting bronchodilator (LABA), theophylline, leukotreine receptor antagonists (LTRAs).
  
  
• Asthma control plus no additional change in therapy (where change is not driven by possible cost saving) [ Time Frame: One-year outcome period ] [ Designated as safety issue: No ]

  1. Exacerbation:

     1. Unscheduled hospital admissions / A&E attendance for asthma, OR
     2. Acute use of oral steroids

     AND

  2. No consultations, hospital admissions or A&E attendance for lower respiratory tract infections (LRTI) requiring antibiotics§

     AND

  3. No change in therapeutic regimen:

     1. Increased dose of ICS, and/or
     2. Use of additional therapy as defined by: long-acting bronchodilator (LABA), theophylline, leukotreine receptor antagonists (LTRAs).
  
  
• Respiratory-related hospitalisations and referrals [ Time Frame: One-year outcome period ] [ Designated as safety issue: Yes ]
  Mean number of respiratory-related hospitalisations and referrals per patient during the outcome year
  
  

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.7 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.13

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.

The aim of this study is to compare the absolute and relative 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 outcomes and prescribing practice between the two countries.