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Uptake and characteristics of zoledronic acid and denosumab patients and physicians in Ontario, Canada: impact of drug formulary access

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Abstract

Summary

The addition of Limited Use criteria (less restrictive access) for zoledronic acid resulted in an immediate and significant increase in uptake and resulted in differences in patient/physician characteristics. In comparison, the uptake of denosumab (only listed with Limited Use) was rapid. Thus, formulary access restrictions have significant implications for prescribing.

Introduction

We sought to describe the use of zoledronic acid and denosumab by physicians and patients over time and examine the impact of a 2012 provincial formulary modification that removed the administrative burden on physicians when prescribing zoledronic acid.

Methods

We identified users of zoledronic acid and denosumab using Ontario pharmacy claims data. The number of new patients and physicians was plotted and examined over time. Interrupted time series analysis examined the impact of a formulary modification to zoledronic acid use and prescribing. Descriptive characteristics of patients and prescribers were summarized pre- and post-formulary modification for zoledronic acid and overall for denosumab.

Results

We identified 1463 zoledronic acid patients treated by 627 physicians and 16,736 denosumab patients treated by 2904 physicians. In the first 2 months on the market, we identified a rapid uptake of denosumab (>450 physicians and >1200 patients) in contrast to zoledronic acid (<10 physicians and <10 patients). Zoledronic acid use increased significantly in the 2-month post-formulary change, yet no change in denosumab was observed. Prior to the formulary modification, more zoledronic acid patients had a history of osteoporosis therapy (41 vs. 26 %) or bone density testing (30 vs. 10 %). Compared to zoledronic patients (post-formulary modification), more denosumab patients had prior osteoporosis therapy (55 vs. 26 %), yet fewer had a gastrointestinal diagnosis (6 vs. 11 %).

Conclusion

We identified a rapid uptake of denosumab in only 15 months of observation. A provincial formulary modification to zoledronic acid resulted in an increase in utilization and impacted patient characteristics.

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Acknowledgments

This research was supported by a research grant to Dr. Cadarette from the Ontario Ministry of Research and Innovation (OMRI, Early Research Award ER09-06-043). Dr. Cadarette was supported by a CIHR New Investigator Award in Aging and Osteoporosis (MSH-95364), Andrea Burden was supported by an Ontario Graduate Scholarship for doctoral research, and Mina Tadrous was supported by a CIHR Doctoral Award—Frederick Banting and Charles Best Canada Graduate Scholarship (GSD-11342). The authors acknowledge Brogan Inc. for providing access to drug identification numbers used to identify eligible drugs and the Institute for Clinical Evaluative Sciences (ICES) where all data analyses were completed. ICES is a non-profit research corporation funded by the Ontario Ministry of Health and Long-Term Care. As a prescribed entity under Ontario’s privacy law (Section 45 of the Personal Health Information Protection Act and Regulation 329/04, Section 18), ICES is legally permitted to receive and use personal health information for health services research. To have this privilege, ICES maintains policies, practices, and procedures that are approved and regularly audited by the Information and Privacy Commissioner of Ontario (www.ipc.on.ca). The opinions, results, and conclusions are those of the authors and are independent from the funding sources. No endorsement by CIHR, ICES, OMRI, or the Ontario Ministry of Health and Long-Term Care is intended or should be inferred.

A portion of this research was presented at the following conferences: The International Osteoporosis Foundation World Congress on Osteoporosis, Osteoarthritis, and Musculoskeletal Diseases in Seville, Spain, April 2014; The Canadian Association for Health Services and Policy Research Annual Conference in Toronto ON, Canada, May 2014. This work has also been accepted for presentation at the American Society for Bone and Mineral Research Annual Meeting in Houston, TX, USA, September 2014, and at the International Conference of Pharmacoepidemiology and Therapeutic Risk Management in Taipei, Taiwan, October 2014.

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Authors and Affiliations

  1. Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON, M5S 3M2, Canada

    A. M. Burden, M. Tadrous & S. M. Cadarette

  2. Institute for Clinical Evaluative Sciences, Toronto, ON, Canada

    A. Calzavara & S. M. Cadarette

Authors
  1. A. M. Burden
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  2. M. Tadrous
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  3. A. Calzavara
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  4. S. M. Cadarette
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Correspondence to A. M. Burden.

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Burden, A.M., Tadrous, M., Calzavara, A. et al. Uptake and characteristics of zoledronic acid and denosumab patients and physicians in Ontario, Canada: impact of drug formulary access. Osteoporos Int 26, 1525–1533 (2015). https://doi.org/10.1007/s00198-014-3023-8

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  • DOI: https://doi.org/10.1007/s00198-014-3023-8

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