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Inhaled corticosteroids for asthma: impact of practice level device switching on asthma control

Mike Thomas1*, David Price1, Henry Chrystyn2, Andrew Lloyd3, Angela E Williams4 and Julie von Ziegenweidt5

Author Affiliations

1 Department of General Practice and Primary Care, University of Aberdeen, Foresterhill Health Centre, Westburn Road, Aberdeen, UK

2 Division of Pharmacy and Pharmaceutical Sciences, School of Applied Sciences, University of Huddersfield, Huddersfield, HD1 3DH, UK

3 Oxford Outcomes Ltd, Oxford, UK

4 Global Health Outcomes, GlaxoSmithKline R&D, Uxbridge, Middlesex, UK

5 Respiratory Research, Ltd, Sankence, UK

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BMC Pulmonary Medicine 2009, 9:1  doi:10.1186/1471-2466-9-1

Published: 2 January 2009



As more inhaled corticosteroid (ICS) devices become available, there may be pressure for health-care providers to switch patients with asthma to cheaper inhaler devices. Our objective was to evaluate impact on asthma control of inhaler device switching without an accompanying consultation in general practice.


This 2-year retrospective matched cohort study used the UK General Practice Research Database to identify practices where ICS devices were changed without a consultation for ≥5 patients within 3 months. Patients 6–65 years of age from these practices whose ICS device was switched were individually matched with patients using the same ICS device who were not switched. Asthma control over 12 months after the switch was assessed using a composite measure including short-acting β-agonist and oral corticosteroid use, hospitalizations, and subsequent changes to therapy.


A total of 824 patients from 55 practices had a device switch and could be matched. Over half (53%) of device switches were from dry powder to metered-dose inhalers. Fewer patients in switched than matched cohort experienced successful treatment based on the composite measure (20% vs. 34%) and more experienced unsuccessful treatment (51% vs. 38%). After adjusting for possible baseline confounding factors, the odds ratio for treatment success in the switched cohort compared with controls was 0.29 (95% confidence interval [CI], 0.19 to 0.44; p < 0.001) and for unsuccessful treatment was 1.92 (95% CI, 1.47 to 2.56; p < 0.001).


Switching ICS devices without a consultation was associated with worsened asthma control and is therefore inadvisable.