Methodology

1. Three schemes of monitoring patients on ART were modeled using a cohort of HIV infected patients treated with AZT/3TC/Efavirenz WHO Treatment Guidelines US DHHS Treatment Guidelines Reduced Viral Load Sampling 313 ARV-naïve patients from Parkland Hospital HIV Clinic Systems database followed up over 5 yr VL performed at least every 6 months (median 79 days) Each strategy was assessed for cost, time to virologic failure and emergence of TAMs Cost effective model of reduced sampling of viral loads for monitoring anti-retroviral therapy in resource limited settingsSylvia Ojoo, Philip Keiser, Ivy Mwangi, Nathaniel Smith

2. Methodology • Time to virological failure was based on a cohort of 313 ARV naïve patients on AZT/3TC/EFV from the Parkland Hospital HIV Database (UTMB) of which 84 experinced virologic failure over a 5 year period • Cost was based on tests in use in RLS (BD FACSCount and Cavidi ExaVir) modeled on the abive cohort • Time to immunologic failure was based on published data • Potential for development of TAMS was derived from published data

3. Frequency of VL Monitoring

4. Time to Detection of Virologic Failure and Costs of the Three Strategies

5. Conclusions • Reduced viral load sampling detected virologic failures almost as frequently as the DHHS Treatment Guidelines • Emergence of TAMS would be more likely using WHO monitoring strategies • Reduced viral load testing is significantly cheaper than the DHHS and less likely to result in resistance than the WHO treatment strategy and merits further evaluation