The combined use of surgery and radiotherapy to treat patients with epidural cord compression due to metastatic disease: a cost-utility analysis

Abstract

Neoplastic metastatic epidural spinal cord compression is a common complication of cancer that causes pain and progressive neurologic impairment. The previous standard treatment for this condition involved corticosteroids and radiotherapy (RT). Direct decompressive surgery with postoperative radiotherapy (S + RT) is now increasingly being chosen by clinicians to significantly improve patients' ability to walk and reduce their need for opioid analgesics and corticosteroids. A cost-utility analysis was conducted to compare S + RT with RT alone based on the landmark randomized clinical trial by Patchell et al. (2005). It was performed from the perspective of the Ontario Ministry of Health and Long-Term Care. Ontario-based costs were adjusted to 2010 US dollars. S + RT is more costly but also more effective than corticosteroids and RT alone, with an incremental cost-effectiveness ratio of US$250 307 per quality-adjusted life year (QALY) gained. First order probabilistic sensitivity analysis revealed that the probability of S + RT being cost-effective is 18.11%. The cost-effectiveness acceptability curve showed that there is a 91.11% probability of S + RT being cost-effective over RT alone at a willingness-to-pay of US$1 683 000 per QALY. In practice, the results of our study indicate that, by adopting the S + RT strategy, there would still be a chance of 18.11% of not paying extra at a willingness-to-pay of US$50 000 per QALY. Those results are sensitive to the costs of hospice palliative care. Our results suggest that adopting a standard S + RT approach for patients with MSCC is likely to increase health care costs but would result in improved outcomes.

Figures

Fig. 1.

Analytic decision model for cost-utility analysis comparing surgical decompression followed by radiotherapy (S + RT) versus RT-only strategy in the palliative care of patients with metastatic spinal cord compression (MSCC). The decision node (square) indicates a choice facing the clinician with regard to the available strategy options for the base case. In this decision tree, a chance node (circle) represents an event with 2 possible consequences that are not under the clinician’s control. The 4 branches designated by (1) are symmetric and are followed by a Markov node (open circle with an “M” inside). For each Markov model, there are 9 Markov states. The terminal node (diamond) indicates that patients reached their life span.

Fig. 2.

Bubble diagram representation of the Markov model with 3 mutually exclusive health states such that, in any cycle, a patient of the cohort is in only 1 of the 9 Markov states defined by the patient's health state and disposition (alive in home care, alive in a hospice, and dead).

Fig. 3.

Graphic representation of the baseline analysis and 2-way sensitivity analyses comparing the strategy that combines surgical decompression and postoperative radiotherapy (S + RT strategy) with the standard of care (RT-only strategy). (A) Based on the baseline analysis, both strategies are located in the northeastern quadrant that is the nondominant, not-dominated quadrant. The S + RT strategy represents a more costly but more effective approach in comparison with the RT-only strategy. Two-way sensitivity analyses focused on (B) monthly overall costs and (C) effectiveness in quality-adjusted life years (QALYs) of hospice for non-ambulatory individuals with urinary incontinence reinforce the robustness of the model. Red signs indicate The S + RT strategy (the comparator) is identified by the solid area, whereas the RT-only approach (the baseline term) is shown in stripes. Asterisks indicate the actual results of the sensitivity analysis.

Fig. 4.

Comparisons of the strategy that combines surgical decompression and postoperative radiotherapy (S + RT strategy) with the standard of care (RT-only strategy). (A) In the incremental cost-effectiveness scatterplot for the probabilistic sensitivity analysis, the S + RT strategy was compared with the RT-only strategy that was set up as the baseline approach. Each dot represents a result of a Monte Carlo simulation. The ellipse delineates a 95% confidence interval, and the larger dotted line represents a willingness-to-pay of US$50 000. (B) In the acceptability curve, the willingness-to-pay was set from virtually zero dollars per QALY gained (a symbolic way to represent no willingness-to-pay for an extra effect) to US$2 000.000. The vertical dotted lines indicate the willingness-to-pay of US$100 000, US$500 000, and US$1 604 800 which correspond to a proportion of cost-effectiveness of 55.86%, 64.98%, and a maximum of 91.11%, respectively.