Cost Utility and Budget Impact Analysis of Early Treament Initiation With Trastuzumab in the Treatment of Her2 Positive Breast Cancer Patients in Kenya

Abstract

Background Breast cancer is the leading cancer in Kenya with a total of 5985 new cases in 2018. Approximately 15-30 percent of breast cancer cases overexpress human epidermal growth factor receptor 2 (HER2). The treatment regimen for HER2+ breast cancer as per the Kenyan National guidelines for cancer management 2013 recommends the use of trastuzumab for a period 52 weeks which consists of 18 cycles. The National Health Insurance Fund (NHIF) currently only pays for 4 cycles of treatment while the patient covers the cost of the remaining cycles. The cost-effectiveness of this treatment in most low and middle income countries such as Kenya is under debate. Trastuzumab based regimens can be given for 9-weeks and 6, 9, 12, 16 and 24-months. It remains uncertain which of these regimens is most cost-effective. The impact of adoption of any of these regimens on the five-year budget of the NHIF has not been accessed. Objective The objective of this study was to compare the cost effectiveness of early initiation of trastuzumab in the treatment of HER2+ breast cancer as well as to conduct a budget impact assessment of early initiation on the budgets of NHIF and Kenyatta National Hospital (KNH). This was done from the payers perspective Methodology The study was conducted in three different parts. The first part was a cost analysis done using a micro-ingredient/bottom-up approach with the aim of identifying direct medical costs associated with trastuzumab for the management of HER2+ breast cancer. The costing perspective was that of the payer. The second part was a cost utility analysis. Utilities and effectiveness data were obtained from literature. A Markov model was used to evaluate costs and benefits of treatment with trastuzumab over a 5-year time horizon. The cycle length was one month. A willingness to pay threshold for Kenya of US$ 919.11 / KSh 111,212.31 (1 USD was KSh 121 as of 9/10/2022) was used. Probabilistic sensitivity analysis was done to determine the impact of uncertainty of the data. The final part was the budget impact analysis. Modelling was done using base R software, a sensitivity analysis was done using dampack package and transition probabilities were computed using heemod package. xv Results The regimen with the lowest incremental cost effectiveness ratio (ICER) value of 5517148.58 KSh per QALY gained was the 9-week regimen and the 6-months’ regimen had the highest ICER value of 7152616.73 KSh per QALY gained. The 9-, 12-, 16- and 24-month regimens had ICER values of 6640186.45, 6804768.23, 6873653.66 and 6874095.83 KSh per QALY gained respectively. Chemotherapy without trastuzumab was the cheapest but also the least effective option. The 9-week regimen would cost NHIF KSh 4198272901.11 for a period of 5 years for the projected 6100 new patients. The number of vials of trastuzumab consumed by a patient was the most sensitive parameter as per the sensitivity analysis and the effectiveness of the treatment also affected the ICER. Conclusion Based on the costing analysis, the 9-week regimen was cheapest trastuzumab containing regimen. With the current willingness to pay threshold for Kenya of US$ 919.11 / KSh 111,212.31 none of the trastuzumab containing regimens are affordable in the Kenyan context. In order to make any of the trastuzumab containing regimens affordable, the government would need to get significant discounts on trastuzumab and train health care workers on good dispensing practices to avoid wastage. Patients would also need to have good adherence to the treatment for better outcomes and in-turn this will improve the cost-effectiveness ratio. Further studies on the safety and treatment outcomes of trastuzumab are needed in the Kenyan setting