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Cost-effectiveness of routine radiation therapy following conservative surgery for early-stage breast cancer |
Hayman J A, Hillner B E, Harris J R, Weeks J C |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Routine radiation therapy following conservative surgery for early-stage breast cancer.
Study population 60-year old women following conservative surgery.
Setting Secondary care. The economic study was carried out in the United States
Dates to which data relate Effectiveness data were based on a study published in 1995. All cost estimates were in 1995 prices.
Source of effectiveness data The estimate for final outcomes was based on a review of previously completed studies.
Modelling A Markov model was used to assess the incremental cost-effectiveness of adding radiation therapy to breast-conserving surgery for the local treatment of early-stage breast cancer. Using a cycle time of 1 year, the model monitored an imaginary cohort of 60-year old women over a 10-year time horizon. For each year, the model tallied the proportion of patients who transitioned between health states, adjusting for quality of life and accounting for costs in the process. The outcomes and costs of the two competing strategies after 10 years were then compared and the incremental cost-effectiveness of radiation therapy in this clinical setting was calculated.
Outcomes assessed in the review The outcomes assessed in the review were the annual probability of a local recurrence, overall survival and the rate of distant metastases.
Study designs and other criteria for inclusion in the review Randomised controlled trials were included in the review.
Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Randomized trials with broad entry criteria and long follow-up period.
Methods used to judge relevance and validity, and for extracting data Number of primary studies included There have been five prospective fully published randomised trials which examined the impact of the addition of radiation therapy to breast-conserving surgery.
Methods of combining primary studies The authors used the National Surgical Adjuvant Breast and Bowel Project B-06 trial as the source of their baseline estimates of the efficacy of radiation therapy as it had the broadest entry criteria, used the type of breast-conserving surgery most commonly performed in North America, included patients who received adjuvant systemic therapy, and had the longest follow-up duration.
Investigation of differences between primary studies Results of the review The annual probability of a local recurrence as the first site of failure was 3.6% without radiation therapy and 0.9% with it, a relative reduction of 75%. However, based on the trial results to date, radiation therapy has no impact on overall survival in the baseline model and the rate of distant metastases was the same with or without radiation therapy.
Measure of benefits used in the economic analysis Quality adjusted life years (QALYs) were used as the outcome measure in the economic analysis. The utilities of 97 actual breast cancer patients who had been treated with lumpectomy and radiation therapy were collected during interviews using the standard gamble technique. A Markov model was used to assess the incremental effectiveness of adding radiation therapy to breast-conserving surgery for the local treatment of early-stage breast cancer over a 10-year time horizon.
Direct costs Costs were discounted at a baseline rate of 3%. Direct medical costs were included in the baseline analysis. Baseline hospital-based costs were calculated by first allocating the Medicare charges for these procedures to the appropriate cost-to-charge ratio. These cost-to-charge ratios were obtained from the Medical College of Virginia's 1995 Medicare Cost Report. Baseline professional costs were estimated by multiplying the relative value units (RVU) for the relevant procedure by an institution specific estimate of their cost per RVU. This estimate was based on the best estimate of professional effort in light of local patterns of payment by preferred provider insurance plans. Given that all patients were assumed to have undergone a lumpectomy and axillary dissection, the costs of these procedures were not included in this incremental analysis.
Indirect Costs Patients' time costs were estimated for treatment with radiation therapy, salvage lumpectomy and radiation therapy, and salvage mastectomy and reconstructive surgery by using estimates of the average hourly wage for females aged 60 to 64 and the number of hours expended by patients seeking and receiving treatment. The average hourly wage was estimated using 1995 age- and sex-specific wage data published by the US Census Bureau. Travel costs were calculated by estimating the average miles patients travel coming in for clinic visits and treatment (20 miles), an estimate of the average cost per mile (31 cents/mile) and the cost of parking ($2/hour).
Sensitivity analysis A sensitivity analysis was performed; all probabilities of outcomes and cost estimates were varied over clinically or economically relevant ranges.
Estimated benefits used in the economic analysis The average life expectancy was the same for both strategies, 7.81 years. However, when the quality of life was taken into account, the use of radiation therapy resulted in a better quality-adjusted survival (7.19 QALYs) than the strategy which involved no radiation therapy (6.84 QALYs). Benefits were discounted at a rate of 3%.
Cost results The baseline analysis demonstrated that the addition of radiation therapy increased the mean breast cancer treatment cost per patient from $17,400 to $27,200.
Synthesis of costs and benefits The incremental cost-effectiveness of the strategy of breast-conserving surgery plus radiation therapy, compared with breast-conserving surgery alone, was the ratio of the incremental cost ($9,800) divided by the incremental benefit (0.35 QALYs) or $28,000 per QALY. Sensitivity analyses show that the cost-effectiveness is most heavily influenced by the cost of radiation therapy and by the resulting quality-of-life benefit due to a reduced fear of local recurrence.
Authors' conclusions The ability of radiation therapy to improve women's quality of life and diminish future salvage costs justifies the additional initial cost and payers should therefore continue to consider such treatment a standard and cost-effective component of breast-conserving therapy for early-stage breast cancer.
CRD COMMENTARY - Selection of comparators The reason for the choice of comparator is clear. Validity of estimate of measure of effectiveness Further details of the other randomised controlled trials that have examined the impact of the addition of radiation therapy to breast-conserving treatment would have been helpful. As the authors noted, the utilities used in the model were based on actual patients who had undergone radiation therapy and had not experienced a recurrence and might, therefore, be biased toward radiation therapy. Furthermore, the model only considered the costs and benefits for 60-year old patients. Validity of estimate of costs Quantities were not reported separately from cost estimates. Treatment costs were based on estimates from only one institution. Other issues The results may not be generalisable to other settings or countries. However, appropriate comparisons were made with other cost-effectiveness studies. Bibliographic details Hayman J A, Hillner B E, Harris J R, Weeks J C. Cost-effectiveness of routine radiation therapy following conservative surgery for early-stage breast cancer. Journal of Clinical Oncology 1998; 16(3): 1022-1029 Indexing Status Subject indexing assigned by NLM MeSH Breast Neoplasms /economics /radiotherapy /surgery; Cost-Benefit Analysis; Female; Humans; Markov Chains; Mastectomy /economics; Probability; Quality-Adjusted Life Years; Radiotherapy /economics; Radiotherapy, Adjuvant /economics; Survival Rate AccessionNumber 21998000419 Date bibliographic record published 31/10/1999 Date abstract record published 31/10/1999 |
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