Pharmacoeconomic evaluation of efavirenz-based antiretroviral therary compared with nevirapine-based therapy among Thai HIV/AIDS Patients

Abstract

NVP-based or GPO-VIR has been recommended for the first line therapy for Thai HIV/AIDS patients. Negative consequences from serious adverse drug reactions such as Hepatotoxicity, Steven Johnson Syndrome (SJS), Toxic Epidermal Necrolysis (TEN) raised concern among health care providers. The aim of this study was to evaluate cost-effectiveness of the treatment starting with EFV-based therapy as compared with NVP-based therapy in Thai HIV/AIDS patients. A probabilistic Markov model applied to HIV/AIDS patients aged 15 to 65 years was developed to compare the marginal cost and marginal benefit of starting with EFV-based regimens and NVP-based regimens. Input parameters were extracted from cohort study of the four regional hospitals under this study. Only relative risk of death of the two medications from published article was used in the survival rate calculation. The study explored the effects of uncertainty around input parameters, presented as cost-effectiveness plane and cost-effectiveness acceptability (AC) curves. The results indicated that starting with NVP-based increase the risk of having serious adverse events such as hepatitis, cirrhosis, SJS, and TEN (11.3, 5.2, 3.5, 0.9 per 1,000 person-year, respectively), compared with EFV-based regimens. Using a health care provider perspective, the lifetime treatment cost of patients who started with EFV-based was less costly than NVP-based regimens in all age groups except for those who were 20 years. Starting with NVP-based had slightly higher LY gain than EFV-based in aged-group of 30 to 60 years, but had less DALY averted than EFV-based regimens. The findings from AC curves revealed that in patients 20 years, starting with NVP-based was the preferable choice at no extra budget available, however, starting with EFV-based was preferred when the WTP was above 3,000,000 Baht/LY gained. In each group of patient aged 30, 40, 50, and 60 years, the initial therapy using EFV-based was the preferable choice. In terms of cost-utility (baht per DALY averted), starting with EFV-based regimens was the preferable choice in all age groups except those who were 20 years. In this group, starting with EFV-based was preferable when the WTP was above 1,000,000 Baht/LY gained. Given a maximum acceptable willingness to pay threshold of 270,000 Baht/DALY starting with EFV-based was cost effective in all aged group except those who were 20 years. It can be concluded that EFV-based was a preferable choice in terms of cost per DALY averted as well as cost per LY gained, except in patients with 20 years. Presently, due to the decrease of the cost of EFV resulting from the compulsory licensing by the Ministry of Public Health, starting with EFV-based is more cost-effective than NVP-based. It is recommended that EFV-based should be used as the first line regimen for Thai HIV/AIDS patients.