Cost‐effectiveness of zoledronic acid and strontium‐89 as bone protecting treatments in addition to chemotherapy in patients with metastatic castrate‐refractory prostate cancer: results from the <scp>TRAPEZE</scp> trial (<scp>ISRCTN</scp> 12808747)

Abstract

<jats:sec><jats:title>Objective</jats:title><jats:p>To evaluate the cost‐effectiveness of adding zoledronic acid or strontium‐89 to standard docetaxel chemotherapy for patients with castrate‐refractory prostate cancer (<jats:styled-content style="fixed-case">CRPC</jats:styled-content>).</jats:p></jats:sec><jats:sec><jats:title>Patients and methods</jats:title><jats:p>Data on resource use and quality of life for 707 patients collected prospectively in the <jats:styled-content style="fixed-case">TRAPEZE</jats:styled-content> 2 × 2 factorial randomised trial (<jats:styled-content style="fixed-case">ISRCTN</jats:styled-content> 12808747) were used to assess the cost‐effectiveness of i) zoledronic acid versus no zoledronic acid (ZA vs. no ZA), and ii) strontium‐89 versus no strontium‐89 (Sr89 vs. no Sr89). Costs were estimated from the perspective of the National Health Service in the <jats:styled-content style="fixed-case">UK</jats:styled-content> and included expenditures for trial treatments, concomitant medications, and use of related hospital and primary care services. Quality‐adjusted life‐years (<jats:styled-content style="fixed-case">QALY</jats:styled-content>s) were calculated according to patients' responses to the generic EuroQol <jats:styled-content style="fixed-case">EQ</jats:styled-content>‐5D‐3L instrument, which evaluates health status. Results are expressed as incremental cost‐effectiveness ratios (<jats:styled-content style="fixed-case">ICER</jats:styled-content>s) and cost‐effectiveness acceptability curves.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The per‐patient cost for <jats:styled-content style="fixed-case">ZA</jats:styled-content> was £12 667, £251 higher than the equivalent cost in the no <jats:styled-content style="fixed-case">ZA</jats:styled-content> group. Patients in the <jats:styled-content style="fixed-case">ZA</jats:styled-content> group had on average 0.03 <jats:styled-content style="fixed-case">QALY</jats:styled-content>s more than their counterparts in no <jats:styled-content style="fixed-case">ZA</jats:styled-content> group. The <jats:styled-content style="fixed-case">ICER</jats:styled-content> for this comparison was £8 005. Sr89 was associated with a cost of £13 230, £1365 higher than no Sr89, and a gain of 0.08 <jats:styled-content style="fixed-case">QALY</jats:styled-content>s compared to no Sr89. The <jats:styled-content style="fixed-case">ICER</jats:styled-content> for Sr89 was £16 884. The probabilities of <jats:styled-content style="fixed-case">ZA</jats:styled-content> and Sr89 being cost‐effective were 0.64 and 0.60, respectively.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>The addition of bone‐targeting treatments to standard chemotherapy led to a small improvement in <jats:styled-content style="fixed-case">QALY</jats:styled-content>s for a modest increase in cost (or cost‐savings). <jats:styled-content style="fixed-case">ZA</jats:styled-content> and Sr89 resulted in <jats:styled-content style="fixed-case">ICER</jats:styled-content>s below conventional willingness‐to‐pay per <jats:styled-content style="fixed-case">QALY</jats:styled-content> thresholds, suggesting that their addition to chemotherapy may represent a cost‐effective use of resources.</jats:p></jats:sec>