Open Access

ARTICLE

Cost-effectiveness analysis of metformin with enzalutamide in the metastatic castrate-resistant prostate cancer setting

Jordan Hill¹, Mike Paulden², Christopher McCabe², Scott A. North³, Peter Venner³, Nawaid Usmani¹

1 Department of Radiation Oncology, University of Alberta, Edmonton, Alberta, Canada
2 Department of Health Economics, University of Alberta, Edmonton, Alberta, Canada
3 Department of Medical Oncology, University of Alberta, Edmonton, Alberta, Canada
AddresscorrespondencetoDr.NawaidUsmani,Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2 Canada

Canadian Journal of Urology 2019, 26(6), 10045-10053.

Abstract

Introduction: Enzalutamide (Enza) is an effective treatmentformetastaticcastrate-resistantprostatecancer (mCPRC). However, Enza is not cost-effective (CE) at willingness to pay (WTP) thresholds from $0-$125 000/quality adjusted life years (QALYs) and is therefore a strain on valuable health care dollars. Metformin (Met) isinexpensive(~$8.00/month)andisthoughttoimprove prostate cancer specifc and overall survival compared to thosenottakingMet.Wehypothesizedthattheremustbe an added effect Met could provide that would make Enza CEtherebyalleviatingthisfnancialstrainongovernment health care budgets.
Materials and methods: We constructed a Markov model and performed a threshold analysis to narrow in on the added effect needed to make such a combination therapy cost-effective at various WTP thresholds.
Results: At a WTP threshold of $50 000/QALY Enza + Met is unlikely to be CE unless it increases Enza’s effcacy by more than 30%. At a WTP threshold of $100 000, Enza + Met could be CE barring Met adds 18.73% to the effcacy of Enza.
Conclusions: Enza + Met is unlikely to be CE at WTP thresholds less than $100 000/QALY; these results make sense because a therapy that is not CE at these WTP thresholds by itself is unlikely to be CE with an adjuvant therapy that keep a patient on such a treatment for even longer. Finally, our model suggests that the mCRPC setting is not the optimal place to trial adding Met as the relative costs are high and utility values low.

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