Predicting treatment discontinuation among patients with multiple sclerosis: application of the transtheoretical model of change.

Objective: To delineate factors associated with discontinued use of the multiple sclerosis (MS) medication Avonex (interferon beta-1a--Biogen) as part of an effort to develop an intervention to promote treatment persistency.

Design: In-depth telephone interviews followed by a 12-page written questionnaire delivered by mail.

Setting: United States.

Participants: Of 946 patients with MS who were contacted, 531 (56%) completed questionnaires; 79% of respondents were currently using Avonex for treatment of MS.

Main Outcome Measure: Discontinuation of Avonex treatment, with analysis based on the theoretical framework of the Transtheoretical Model of Change.

Results: Four key variables (pros of Avonex use, cons of Avonex use, highest level of education completed, and level of disability) accurately identified 82% of patients who discontinued Avonex use, while also correctly identifying 81% of patients who stayed on the drug.

Conclusion: Constructs from the Transtheoretical Model of Change were effective in differentiating patients who had discontinued their Avonex treatment versus patients who continued treatment. This behavioral model likely would be an effective framework for a medication persistency intervention.