Purpose: Five novel drugs introduced since 2006 improve outcomes for patients with advanced Human Immunodeficiency Virus (HIV) infection virus at a median annual cost of US $11,800 each. We compared the cost-effectiveness of a treatment strategy using these new antiretrovirals compared with a strategy using conventional antiretrovirals in patients with multi-drug resistant HIV.
Method: We updated a published HIV model of HIV infection to characterize advanced disease. Health states were defined according to regimen, viral load, CD4 count, adverse event history, and intercurrent AIDS illness. We derived data from the Options in Management of Antiretrovirals trial for parameters describing the clinical course, costs, and utility of treatment-experienced patients with multi-drug resistant HIV who received conventional antiretrovirals. Additional parameters were derived from the literature. We calibrated the model to observed survival, development of new AIDS illnesses, cumulative costs, and quality-adjusted life years (QALYs) in the trial. We estimated the efficacy of new antiretrovirals from a systematic review of randomized trials and pooled data to estimate the odds of increasing virologic suppression. We estimated costs assuming that a new regimen would contain one or two new antiretrovirals, that individuals could discontinue ineffective drugs, and that individuals would have two chances to achieve viral suppression before exhausting treatment options that aim to suppress the virus.
Result: At the pooled odds ratio for virologic suppression with new antiretrovirals (3.4) the projected increase in life expectancy was 4.6 years. At the upper and lower bounds of the 95% confidence interval (2.7 and 4.4), the increases were 3.9 and 6.0 years, respectively. For regimens containing one additional new antiretroviral, the cost-effectiveness ratio was $38,019/life year and $56,234/QALY compared with conventional treatment. With two new antiretrovirals added and 0, 1, or 2 conventional antiretrovirals discontinued, the cost/QALY ratios compared to conventional treatment were $83,059, $72,668, and $63,465 respectively. For patients with extensively drug-resistant HIV (probability of suppression with conventional antiretrovirals <10%), substituting two new antiretrovirals was associated with cost/QALY ratios below $56,000. Results were also sensitive to assumptions regarding toxicity, quality of life, and disease progression.
Conclusion: New antiretroviral drugs for the treatment of HIV are cost-effective at conventional thresholds, particularly for patients with extensively drug resistant HIV and when ineffective antiretroviral drugs are removed simultaneous with the addition of new drugs.
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