Medication adherence, first episode duration, overall duration and time without therapy: the example of bisphosphonates

Authors

  • Elizabeth E. Roughead PhD,

    Corresponding author
    1. Quality Use of Medicines and Pharmacy Research Centre; Sansom Institute, University of South Australia, Australia
    • Quality Use of Medicines and Pharmacy Research Centre; Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, GPO Box 2471, Adelaide, South Australia 5001, Australia.
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    • Associate Professor.

  • Emmae Ramsay BSc G.Dip.App.Stats,

    1. Data Management and Analysis Centre, Discipline of Public Health, University of Adelaide, Australia
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  • Kym Priess PhD,

    1. Quality Use of Medicines and Pharmacy Research Centre; Sansom Institute, University of South Australia, Australia
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  • John Barratt B Pharm, B App Sc (Computer Science) Grad Dip Community Pharmacy Practice,

    1. Quality Use of Medicines and Pharmacy Research Centre; Sansom Institute, University of South Australia, Australia
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  • Philip Ryan MBBS,

    1. Data Management and Analysis Centre, Discipline of Public Health, University of Adelaide, Australia
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  • Andrew L. Gilbert PhD

    1. Quality Use of Medicines and Pharmacy Research Centre; Sansom Institute, University of South Australia, Australia
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  • Conflict of interest was declared.

Abstract

Purpose

We aimed to determine the duration of first episode of therapy and overall therapy as well as time without treatment for bisphosphonates.

Methods

Data were extracted from Department of Veterans' Affairs (DVA) dataset for those with at least one dispensing for a bisphosphonate between April 2001 and April 2007. Episodes of use were determined as the number of treatment days between the first and last prescription plus 35 days once a dispensing gap of 105 days had been reached, or where no treatment gaps were recorded, the study end date. Kaplan–Meier analyses were undertaken for the first episode of use, overall duration and time without treatment.

Results

When considering only the duration of first episode, median bisphosphonate use was 1.19 years. The median duration extended to 3.27 years when all episodes of use were considered. Overall, 52.0% of subjects reached at least 3 years of treatment and 66.5% of existing users had a duration of at least 3 years. Median time without treatment was 1.65 years. Overall, 81% of the cohort had enough medicine dispensed to be considered adherent throughout their duration of use.

Conclusion

Over 50% of subjects and 66% of existing users had duration consistent with the minimum recommended. Adherence within an episode was high. The focus for improving duration of bisphosphonate use should be on reducing the time without treatment, rather than adherence at the time of use. Studies assessing only the first episode of use in new users of medicines may underestimate duration. Copyright © 2008 John Wiley & Sons, Ltd.

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