Supervised Exercise for Patients With Metastatic Breast Cancer: A Cost-Utility Analysis Alongside the PREFERABLE-EFFECT Randomized Controlled Trial

Abstract

Purpose: To evaluate the cost utility of a 9-month supervised exercise program for patients with metastatic breast cancer (mBC), compared with control (usual care, supplemented with general activity advice and an activity tracker). Evidence on the cost-effectiveness of exercise for patients with mBC is essential for implementation in clinical practice and is currently lacking.

Methods: A cost-utility analysis was performed alongside the multinational PREFERABLE-EFFECT randomized controlled trial, conducted in 8 centers across Europe and Australia. Patients with mBC (N = 357) were randomly assigned to either a 9-month, twice-weekly, supervised exercise group (EG) or control group (CG). Costs of the exercise program were calculated through a bottom-up approach. Other health care resource use, productivity losses, and quality of life were collected using country-adapted, self-reported questionnaires. Analyses were conducted from a societal perspective with a time horizon of 9 months. Costs were collected and reported in 2021 Euros (€1 = $1.18 US dollars).

Results: Compared with the CG, EG resulted in a quality-adjusted life-year (QALY) gain of 0.013 (95% CI, -0.02 to 0.05) over a 9-month period. The mean costs of the exercise program were €1,696 per patient with one-on-one supervision (scenario 1) and €609 with one-on-four supervision (scenario 2). These costs were offset by savings in health care and productivity costs, resulting in mean total cost differences of -€163 (scenario 1) and -€1,249 (scenario 2) in favor of EG. The probability of supervised exercise being cost-effective was 65% in scenario 1 and 91% in scenario 2 at a willingness-to-pay threshold of €20,000 per QALY.

Conclusion: Exercise for patients with mBC increases quality of life, decreases costs, and is likely to be cost-effective. Group-based supervision is expected to have even higher cost-savings. Our positive findings can inform reimbursement of supervised exercise interventions for patients with mBC.

Trial registration: ClinicalTrials.gov NCT04120298.

FIG 1.

CONSORT diagram. Flow of participants through the study.

FIG 2.

Cost-effectiveness plane (left) and cost-effectiveness acceptability curve (right) for (A) one-on-one supervision and (B) one-on-four supervision. WTA = WTP: points in the southwest quadrant are included if (difference in costs/difference in QALY) > WTP. WTA = 0: points in the southwest quadrant are excluded. The cost-effectiveness plane displays the difference in costs (vertical axis) and difference in QALY (QALYs, horizontal axis) between the intervention (EG; 9-month exercise program) and CG after 5,000 bootstrap iterations. Every dot indicates the difference in costs and QALYs (ie, a cost-effect pair) between EG and CG of one bootstrap iteration, thus representing the uncertainty of the analysis. The red dot indicates the difference in costs and QALYs between EG and CG before bootstrapping, while the shades of blue represent the density of bootstrap iterations (lighter = higher density). The percentage of bootstrap iterations per quadrant is displayed in the figures and Table 4. If the cost-effect pair falls within the NW or southeast quadrant, the choice between EG and CG is clear. In the southeast quadrant, EG is more effective and less costly compared with CG, and therefore dominates CG. In the NW quadrant, the opposite is true. In the SW and NE quadrants, the choice depends on the maximum cost-effectiveness ratio one is willing to accept. The cost-effectiveness acceptability curve displays the probability of cost-effectiveness of EG for every WTP threshold. This probability is based on the number of bootstrap iterations that are considered cost-effective at a certain threshold (ie, either lower costs and higher effectiveness for EG, or higher costs and higher effectiveness, whereby the costs per QALY gained are lower than the WTP threshold). The higher the WTP threshold, the higher the probability of cost-effectiveness. The primary one-on-four scenario is cost-effective at lower WTP thresholds than the one-on-one scenario. CG, control group; EG, exercise group; NE, northeast quadrant; NW, northwest quadrant; QALY, quality-adjusted life-year; SE, southeast quadrant; SW, southwest quadrant; WTA, willingness-to-accept (willingness to accept lower QALYs if it comes with lower costs); WTP, willingness-to-pay (willingness to pay for additional QALYs).