Projecting the benefits of antiretroviral therapy for HIV prevention: the impact of population mobility and linkage to care.
BACKGROUND
Recent mathematical models suggested that frequent human immunodeficiency virus (HIV) testing with immediate initiation of antiretroviral therapy (ART) to individuals with a positive test result could profoundly curb transmission. The debate about ART as prevention has focused largely on parameter values. We aimed to evaluate structural assumptions regarding linkage to care and population mobility, which have received less attention.


METHODS
We modified the linkage structure of published models of ART as prevention, such that individuals who decline initial testing or treatment do not link to care until late-stage HIV infection. We then added population mobility to the models. We populated the models with demographic, clinical, immigration, emigration, and linkage data from a South African township.


RESULTS
In the refined linkage model, elimination of HIV transmission (defined as an incidence of <0.1%) did not occur by 30 years, even with optimistic assumptions about the linkage rate. Across a wide range of estimates, models were more sensitive to structural assumptions about linkage than to parameter values. Incorporating population mobility further attenuated the reduction in incidence conferred by ART as prevention.


CONCLUSIONS
Linkage to care and population mobility are critical features of ART-as-prevention models. Clinical trials should incorporate relevant data on linkage to care and migration to evaluate the impact of this strategy.
Division of Infectious Diseases, Massachusetts General Hospital, 50 Staniford St, 9th Fl, Boston, MA 02114, USA. jandrews6@partners.org
Jason R
JR
Andrews
Robin
R
Wood
Linda-Gail
LG
Bekker
Keren
K
Middelkoop
Rochelle P
RP
Walensky
D000293:Adolescent; D019380:Anti-HIV Agents / Q000008:administration & dosage*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods*; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D004641:Emigration and Immigration; D015658:HIV Infections / Q000175:diagnosis / Q000188:drug therapy* / Q000517:prevention & control* / Q000635:transmission; D006297:Health Services Accessibility; D006801:Humans; D008962:Models, Theoretical; D010342:Patient Acceptance of Health Care; D013019:South Africa
D019380:Anti-HIV Agents