Home testing and counselling to reduce HIV incidence in a generalised epidemic setting: a mathematical modelling analysis

Background Home HIV testing and counselling (HTC) achieves high levels of HIV testing and linkage to care. Periodic home HTC, particularly targeted to those with high HIV viral load, might facilitate expansion of antiretroviral therapy (ART) coverage. We used a mathematical model to assess the effect of periodic home HTC programmes on HIV incidence in KwaZulu-Natal, South Africa. Methods We developed a dynamic HIV transmission model with parameters, primary cost data, and measures of viral suppression collected from a prospective study of home HTC in KwaZulu-Natal. In our model, we assumed home HTC took place every 5 years with ART initiation for people with CD4 counts of 350 cells per mu L or less. For individuals with CD4 counts of more than 350 cells per mu L, we compared increasing ART coverage for those with 350-500 cells per mu L with initiating treatment for those who have viral loads of more than 10 000 copies per mL. Findings Maintaining the presently observed level of 36% viral suppression in HIV-positive people, HIV incidence decreases by 33.8% over 10 years. Home HTC every 5 years with linkage to care with ART initiation at CD4 counts of 350 cells per mu L or less reduces HIV incidence by 40.6% over 10 years. Expansion of ART to people with CD4 counts of more than 350 cells per mu L who also have a viral load of 10 000 copies per mL or more decreases HIV incidence by 51.6%, and this was the most cost-effective strategy for prevention of HIV infections at US$2960 per infection averted. Expansion of ART eligibility CD4 counts of 350-500 cells per mu L is cost-effective at $900 per quality-adjusted life-year gained. Following health economic guidelines, expansion of ART use to individuals who have viral loads of more than 10 000 copies per mL among those with CD4 counts of more than 350 cells per mu L was cost-effective to reduce HIV-related morbidity. Interpretation Our results show that province-wide home HTC every 5 years can be a cost-effective strategy to increase ART coverage and reduce HIV burden. Expanded ART initiation criteria that includes individuals with high viral load will improve the effectiveness of home HTC in linking individuals to ART who are at high risk of transmitting HIV, thereby preventing morbidity and onward transmission.