Pharmacoeconomic modelling for policy decision-making : the case of sofosbuvir for hepatitis C infection in South Africa
The main purpose of this study was to empower policy-makers to make informed decisions about the treatment of chronic hepatitis C in light of the vast array of novel treatments being developed for this disease. A two-dimensional research method was employed, consisting of a literature review and an empirical investigation. The main objective of the literature review was to provide background to the study by conceptualising chronic hepatitis C and other relevant aspects of the disease. The empirical investigation consisted of constructing a decision-analytic Markov model based on the natural history of chronic hepatitis C virus infection and using the resulting model to determine the cost-effectiveness, the public health impact and the budget impact of sofosbuvir, or sofosbuvir-containing regimens for hepatitis C in South Africa. The study design was founded on the concept of pharmacoeconomic modelling and the target population of this research project was patients with chronic hepatitis C virus infection living in South Africa. During the modelling phase, a mathematical decision-analytical model was constructed to simulate the progression of hepatitis C virus infection. The model was then populated with data, including annual transition probabilities, cost data, effectiveness data and utility values. Additional data required for the public health analysis and budget impact analysis included South African prevalence and incidence data. Available literature served as the data source for the transition probabilities, treatment efficacy and health state utilities used in this model. Drug costs were taken from the Official Pharmaceutical Blue-book, whereas costs related to disease or treatment management, including outpatient attendance and inpatient palliative care, were taken from the National Health Referencing Price List. Cost estimates for procedures, diagnostic tests and inpatient admissions for complications of CHC were obtained from private sector cost data. Once the model was complete, TreeAge Pro software (TreeAge Pro 2014, R1.2) used the visual model structure to automatically generate the algorithms required to evaluate the model and yield results. Outcomes from the cost-effectiveness model show that the fixed-dose combination of sofosbuvir-ledipasvir will be cost-effective for South African patients infected with hepatitis C virus genotype 5 at a price of R123 193 (US$10 500) for 12 weeks. Assuming that only 0.18% of all diagnosed patients with hepatitis C are treated annually, liver-related morbidity and mortality in South Africa will continue to rise over the next two decades; with a 32% increase in the number of hepatocellular carcinoma cases, a 38% increase in decompensated cirrhosis cases and a 58.5% increase in the number of liver-related deaths, irrespective of the treatment option chosen. However, if policy-makers and physicians were to aim to scale up the active treatment of hepatitis C to at least 10% of all diagnosed non-cirrhotic chronic hepatitis C patients annually, the impact of antiviral therapy on chronic hepatitis C virus infections is more demonstrable. Furthermore, if policy-makers were to decide to treat patients with sofosbuvir-based regimens such as sofosbuvir-ledipasvir or sofosbuvir + pegylated interferon and ribavirin, instead of the current standard of care, a total of 185 cases of decompensated cirrhosis, 133 cases of hepatocellular carcinoma and 183 liver-related deaths could be avoided over the next two decades. Outcomes from the budget impact analysis showed that the estimated expenditure on hepatitis C virus in South Africa is approximately R29 million per annum, assuming that 100 new patients are treated with the current standard of care each year, and those who failed treatment are followed up. Assuming a price of R82 129.32 (US$7 000) for a 12-week course of sofosbuvir and R123 193 (US$10,500) for sofosbuvir-ledipasvir, treating and managing the same number of patients with sofosbuvir-based therapy would result in a cost-saving of more than R5 000 000 (US$426 157) per year, or R26 338 793 (US$2 244 893) over five years. The estimated budget required to treat ~80% of all patients currently infected with hepatitis C virus in South Africa by the end of 2020 is approximately R76 billion. The next decade will be will be one of rapid innovation in antiviral therapy for chronic hepatitis C. Decision models can help design and evaluate new treatment paradigms that maximise benefits to society as a whole, while promoting a patient-centred healthcare system. Pharmacoeconomic analyses should be used by policy decision-makers as tools to sustain a healthcare system that can continue to reward innovation and afford the next generation of ‘miracle drugs’, such as sofosbuvir.
- Health Sciences