Cost-effectiveness analyses of the conversion of patients with non-insulin-dependent diabetes mellitus from glipizide to glyburide and of the accompanying pharmacy follow-up clinic.

At the Department of Veteran's Affairs Outpatient Clinic in Columbus, Ohio, patients with non-insulin-dependent diabetes mellitus who were receiving glipizide therapy were converted to glyburide therapy over a 6-month period starting in mid-1993. A pharmacy follow-up clinic was instituted to help patients with problems associated with the transition. The conversion was intended to reduce costs by converting from a more expensive to a less expensive drug (in terms of acquisition cost) within the same therapeutic class. An initial analysis of the conversion indicated a savings of $65,000.00 to the Department of Veterans' Affairs (VA) based on the drug acquisition cost differential alone. The purpose of our study was to retrospectively evaluate the cost-effectiveness of the conversion and pharmacy follow-up clinic from the perspective of the VA pharmacy department. Relevant costs and effectiveness (percentage of patients who achieved good glycemic control) were examined for three groups: group I--patients who were treated with glipizide, group II--patients who were treated with glipizide; group II--patients who were switched from glipizide to glyburide, accompanied by a pharmacy follow-up clinic; and group III--patients who were switched from glipizide to glyburide, with no follow-up clinic. Overall, group II had the lowest costs, and group II had to be the most effective. Cost-II effectiveness analysis indicated that, in general, the conversion from glipizide to glyburide was cost-effective. Incremental analysis performed for the follow-up group over the no follow-up group showed that for every 1% of patients who achieved good glycemic control, the VA would spend $1.01 more for the follow-up groups. This was considered to be cost-effective for the VA.