(P14) Cost Effectiveness of Radiation and Chemotherapy for High-Risk Low Grade Glioma

Abstract

The standard of care treatment for maximally resected, high risk (≥ 40 years old or sub-totally resected) low grade glioma (LGG) patients was established by RTOG 9802, which showed an overall survival (OS) of 13.3 years for patients treated with radiotherapy (RT) + PCV (procarbazine, lomustine [CCNU], vincristine) chemotherapy compared to 7.8 years for RT alone. In the era of value-based health care, cost-effectiveness analyses (CEA) have the potential to inform coverage decisions and patient care. To our knowledge, there has been no study assessing the value of RT+PCV as adjuvant therapy for high risk LGG. We sought to analyze the cost-effectiveness of this strategy. The base case comprised patients with high risk LGG after maximal safe resection with indications for adjuvant therapy. A decision tree with an integrated three-state Markov model was created to follow patients treated with RT and RT + PCV. Patients existed in one of 3 health states: stable, progressive, and dead. All patients were assumed to be free of progression at baseline. Survival and freedom from progression were modeled to reflect the results of RTOG 9802 using time-dependent transition probabilities. Health utility values and costs of care were derived from the literature and national registry databases. Starting at initial age of 40 years (median age on RTOG 9802), patients were followed monthly over a maximum time horizon of 60 years after diagnosis (effectively over their remaining lifetimes). Analysis was conducted from the healthcare perspective. Probabilistic sensitivity analysis of modeled parameter distributions was conducted with Monte Carlo simulation of 10,000 samples. Modeled outcomes demonstrated agreement with clinical data in OS, progression free survival (PFS), and expected benefit of addition of PCV to adjuvant RT. In our model, 5-year and 10-year OS rates for RT+PCV vs RT alone were 71.5% vs. 64.8%, and 62.1% vs. 39.2%, respectively; 5-year and 10-year PFS rates for RT+PCV vs RT alone were 61.7% vs. 45.2%, and 50.5% vs. 20.1%, respectively. Patients treated with RT alone accrued 5.17 quality-adjusted life-years (QALYs) (9.63 life-years) at a cost of $139,598. Patients treated with RT+PCV accrued 9.94 QALYs (21.45 life-years) at a cost of $188,234. The addition of PCV to RT yielded an incremental benefit of 4.77 QALYs at an incremental monetary cost of $48,637, leading to an incremental cost-effectiveness ratio of $10,188 per QALY gained. Probabilistic sensitivity analysis demonstrates that cost-effectiveness of RT+PCV was insensitive to variations in modeled distributions of input parameters, with 99.96% probability of cost-effectiveness at a willingness-to-pay threshold of $100,000 per QALY. Based on the impressive benefits in outcomes observed in RTOG 9802, the addition of PCV chemotherapy to RT provides high value for cost in the treatment of patients with high-risk low grade glioma.