Asthma-related prescribing patterns with four different corticosteroid inhaler devices

Four types of corticosteroid inhaler devices are available in New Zealand for first-line treatment of asthma, including two aerosol systems [Autohaler (3M Healthcare Ltd, Loughborough, U.K.; 3M Pharmaceuticals (Australia Pty Ltd, Sydney, Australia) and MDI (Glaxo Wellcome PLC, Ware, U.K.)] and two dry powder systems [Diskhaler (Glaxo Wellcome) and Turbuhaler (Astra AB, Sodertalje, Sweden)]. Rates of asthma-related health care consumption and treatment outcomes associated with use of the different inhalers are unknown. In this retrospective survey, asthma-related primary health care consultation and prescription patterns were compared in a large general practice population for each corticosteroid inhaler device prescribed as first-line treatment. An electronic search of a computerized clinical database yielded the medical records of 5704 patients with physician-diagnosed asthma who were prescribed either the Autohaler, Diskhaler, MDI or Turbuhaler as their sole corticosteroid inhaler device in the previous 12 months. The mean daily inhaled corticosteroid dose was lowest for the Autohaler (569 micrograms day-1; 95% CI: 538-605), followed by the Diskhlaer (638 micrograms day-1; 95% CI: 609-670) and MDI (665 micrograms day-1; 95% CI: 638-673), and was highest for the Turbuhaler (990 micrograms day-1; 95% CI: 954-1029, P < 0.001). A relatively high proportion of patients aged 19-49 years in the Turbuhaler and Diskhaler groups (29% and 23%, respectively) received at least one inhaled corticosteroid prescription including a daily dose greater than 1500 micrograms compared with the MDI group (4%). In the Diskhaler group the mean daily inhaled corticosteroid dose prescribed for adult patients was similar to that for the Turbuhaler group (904 micrograms day-1 and 1058 micrograms day-1, respectively). These data suggest that in New Zealand the dry powder corticosteroid inhaler devices are prescribed for adults at significantly higher doses than the aerosol inhaler devices. Clinical databases of this type yield valuable information on drug utilization in large patient populations and usefully assess clinical prescribing practices.