Economic evaluation of inhalers used in the treatment of asthma

Summary

Asthma is an important disease for New Zealand in terms of prevalence and costs, both direct and indirect. The objective of this study was to determine if there were any differences in primary care medical costs between treatment of asthma with four corticosteroid inhaler drug delivery systems (Autohaler? [AUTO], Diskhaler? [DISK], metered dose inhaler [MDI] and Turbuhaler? [TURB]) in a general practice setting.

The retrospective observational data-based research completed for this study involved a large population and recorded actual general practitioner prescribing practice. The perspective taken was that of the funder of health care. Data were obtained from the computerised clinical records of 28 New Zealand general practices. Cost data were on a per year per patient basis.

The largest single cost item identified in this study was that of corticosteroid inhalers which ranged from 41% of total primary care cost for MDI to 52% for the TURB group. Total drug acquisition cost (inclusive of dispensing costs and wholesale and retail markups) was highest for TURB at $490 and lowest for MDI at $265, a difference of 85%. There was less variation in general practitioner consultations for asthma with total costs ranging from $104 for AUTO to $127 for DISK. Total primary care costs were lowest for MDI at $392 per annum and highest for TURB at $608, a difference of 55%. If the MDI total primary care costs are used as the base for an index (MDI total primary care costs set at 100) then AUTO becomes 116, DISK 134 and TURB 155.

The model was robust with respect to conclusions relating to cost differences between the treatment groups. In all but one instance TURB remains the highest cost group.