Analytical approach:
The analysis was based on a mathematical model of the long-term clinical and economic outcomes of using the 21-gene profile to guide chemotherapy decisions, for women with lymph node-positive hormone receptor-positive breast cancer. A lifetime horizon (40 years) was considered. The authors stated that the perspective of the US health care payer was adopted.
Effectiveness data:
The key data for the treatment effect and the patient characteristics were from a subset of participants in a published clinical trial that compared the 21-gene assay with standard care. Other inputs, especially for the long-term analysis, were from other published sources. Some adjustment of the data was required to reflect the population enrolled in the RxPONDER trial, and some assumptions were made. Survival was a key input for the model.
Monetary benefit and utility valuations:
The utility values were from published sources.
Measure of benefit:
Quality-adjusted life-years (QALYs) were the summary benefit measure, and they were discounted at an annual rate of 3%. Expected QALYs were converted into monetary values using an incremental net benefit approach.
Cost data:
The analysis included the costs of adjuvant chemotherapy, the 21-gene assay, primary and secondary prophylaxis with granulocyte-colony stimulating factor, and the management of recurrence. The costs of implementing the RxPONDER trial were considered. The cost of adjuvant chemotherapy was from a retrospective claims analysis, and the other costs were from published studies. All costs were in US $ and they were discounted at a yearly rate of 3%. The price year was 2010.
Analysis of uncertainty:
The assessment of the expected value of sample information followed a Bayesian framework that simulated the inputs in the model across their distributions. Different distributions were assigned to groups of inputs. The subsequent value of research was extrapolated to the US population, over a 10-year horizon, using nationwide epidemiological databases. Three willingness-to-pay thresholds were used ($100,000, $150,000, and $200,000 per QALY gained).