Purpose: To explore the cost-effectiveness of interventions to improve adherence to combination antiretroviral therapy in patients with human immunodeficiency virus (HIV) infection.
Methods: A simulation model of HIV infection, incorporating CD4 cell count and HIV ribonucleic acid levels as predictors of disease progression, was used to estimate the lifetime costs and quality-adjusted life expectancy associated with clinical interventions to improve adherence to antiretroviral therapy (e.g., directly observed therapy, automatic medication dispensers, beepers, portable alarms) in a clinical trial cohort with early disease (mean CD4 count, 350 cells/microL), a clinical trial cohort with advanced disease (mean CD4 count, 87 cells/microL), and an urban cohort (mean CD4 count, 217 cells/microL). Data were from clinical trials, national databases, and published literature.
Results: For relatively healthy patients with early disease, interventions that reduced virologic failure rates by 10% increased quality-adjusted life expectancy by 3.2 months, whereas those that reduced failure by 80% increased quality-adjusted life expectancy by 34.8 months, as compared with standard care. The cost-effectiveness ratio was below 50000 US dollars per quality-adjusted life-year (QALY) for interventions costing 100 US dollars per month provided that failure rates were reduced by at least 10%, and for those costing 500 US dollars per month provided that failure rates were reduced by more than 50%. For both patients with advanced disease and those from an urban cohort, adherence interventions costing about 500 US dollars per month (e.g., directly observed therapy) had to reduce failure by about 25% to have cost-effectiveness ratios below 50000 US dollars per QALY.
Conclusion: In patients with lower baseline levels of adherence or advanced disease, even very expensive, moderately effective adherence interventions are likely to confer cost-effectiveness benefits that compare favorably with other interventions.