Qvar Versus Clenil, a General Practice Research Database Study

• Severe asthma exacerbation (ATS/ERS based defn) [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  Exacerbation defined as:

  (i) Respiratory-related:

  1. Hospital attendance / admissions OR
  2. A&E attendance OR (ii) Use of acute oral steroids**
  
  
• Primary composite asthma control [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  Where control is defined as absence of:

  (i) Respiratory-related:

  1. Hospital attendance or admission
  2. A&E attendance, OR
  3. Out of hours attendance, OR
  4. Out-patient department attendance (ii) GP consultations for lower respiratory tract infection (iii) Prescriptions for acute courses of oral steroids
  
  

• Exacerbation definition based on clinical experience [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  Defined as:

  (i) Respiratory-related:

  1. Hospital attendance / admissions OR
  2. A&E attendance OR
  3. Out of hours consultation OR
  4. GP consultation OR (ii) Use of acute oral steroids
  
  
• Asthma control + SABA usage [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  Where control requires the absence of:

  (i) Respiratory-related:

  1. Hospital attendance or admission
  2. A&E attendance, OR
  3. Out of hours consultation, OR
  4. Out-patient department attendance (ii) GP consultations for lower respiratory tract infection (iii) Prescriptions for acute courses of oral steroids (iv) Average daily prescribed dose of ≤200mcg salubtamol / ≤500mcg terbutaline
  
  
• Treatment success [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  (i) Control

  a. No respiratory-related: i. Hospital attendance or admission ii. A&E attendance, OR iii. Out of hours consultation, OR iv. Out-patient department attendance b. No GP consultations for lower respiratory tract infection (ii) No prescriptions for acute courses of oral steroids (iii) No additional or change in therapy

  1. Increased dose of ICS (≥50% increase), and/or
  2. Change in ICS and/or
  3. Change in delivery device, and/or
  4. Use of additional therapy as defined by: LABA, theophylline, leukotreine receptor antagonists (LTRAs).
  
  
• Asthma-related hospitalisations [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  Defined as sum of:

  (i) Definite: Hospitalisations coded with an asthma read code (ii) Definite + Probable: Hospitalisations with an asthma read code + uncoded hospitalisations occurring within a 7-day window (either side of the hospitalisation date) of an asthma read code

  
  
• Respiratory hospitalisations [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  Defined as the sum of:

  (i) Definite: Hospitalisations coded with a lower respiratory code (ii) Definite + Probable: Hospitalisations with an asthma read code + uncoded hospitalisations occurring within a 7-day window (either side of the hospitalisation date) of a lower respiratory read code

  
  
• SABA usage [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  Average daily dosage during outcome year - outcome SABA usage will be categorised within ranges used to match baseline SABA use to optimise matching of the treatment arms.
  
  
• ICS compliance [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  Based on prescription refills
  
  
• Oral Thrush [ Time Frame: 1 year ] [ Designated as safety issue: No ]

  Defined as:

  (i) Topical oral anti-fungal prescriptions, and / or (ii) Coded for oral candidiasis

  
  

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.

In response to the Montreal Protocol's ruling to phase out ozone-depleting chlorofluorocarbon (CFC) propellants in asthma inhalers, several hydrofluoroalkane-134a-propellant (HFA-) formulations of BDP have been developed. Two branded generic formulations currently available in the UK are Qvar® (Teva Pharmaceutical Industries Ltd) - an extra-fine-particle (~1.1 microns) HFA-BDP (solution) formulation and Clenil® (Chiesi Limited) - a larger particle (~2.9 microns) HFA-BDP (suspension) formulation.

The extra-fine particle formulation HFA-BDP formulation (Qvar®) has been shown to improve total and small airway deposition relative to CFC-BDP. As a result of the more even distribution through both the large and small airways of the lungs and data from short-term randomised clinical trials (RCTs), Qvar® dosing is recommended at approximately one half the dose of traditional CFC-BDP (average particle size ~3.5 microns). However, the larger-particle Clenil® is recommended for prescribing at the same dose as traditional CFC-BDP.

Further studies are required to understand whether the differences in particle size and airway distribution have an impact on asthma outcomes over the long-term.

This observational study will investigate the real-world effectiveness of extra-fine HFA-BDP (Qvar®) as compared with larger-particle HFA-BDP (Clenil®) in patients with asthma who: were new to ICS therapy; received an increase in their ICS dose, or switched / changed baseline ICS therapy to HFA-BDP with no change in BDP-equivalent ICS dose. We hypothesise that differences in effectiveness might become apparent over the longer term through a retrospective database analysis of one-year outcomes for the diverse patient population seen in primary care.