LHRS 2018

From individual care trajectories to HIV care cascade at population level in rural KwaZulu-Natal (South Africa): the impact of population dynamics


Oral communication presented May 31 2018 at Life History Research Society Conference in Paris.


Joseph Larmarange, Mamadou Hassimiou Diallo, Nuala McGrath, Collins Iwuji, Rodolphe Thiébaut, Frank Tanser, Till Bärninghausen, Deenan Pillay, François Dabis, Joanna Orne-Gliemann for the ANRS 12249 TasP Study Group



The universal test-and-treat strategy (UTT) was developed to maximize the proportion of all HIV-positive individuals on antiretroviral and virally suppressed, assuming that it leads to reduction in HIV incidence. The evolution over time of the cross-sectional population HIV care cascade is determined by longitudinal individual trajectories through the HIV care continuum and the underlying HIV population dynamics. This structural effect could dilute the impact observed at population level of a UTT strategy RT: either add impact on what (incidence) or delete sentence. The purpose of this paper is to quantify the contribution of each component of population change on the population HIV care cascade in the context of UTT.


We used prospective individual-level longitudinal data from the ANRS 12249 cluster-randomized trial which was implemented in rural KwaZulu-Natal, South Africa between 2012 and 2016 to test such an approach.


HIV tests results and information on clinic visits, ART prescription, viral load and CD4 count, migration and deaths were used to calculate residency status, HIV status and HIV care status for each individual on a daily basis. Position within the HIV care continuum was considered as a score ranging from 0 (undiagnosed) to 4 (virally suppressed). We compared the cascade score of each individual joining or leaving the HIV population with the average score of their cluster at the time of entry or exit. Then, we computed the contribution of each event on the average cascade score and the annualised total contribution of all events, considering 5 components of HIV population change: aging into the cohort, HIV seroconversions, in-migrations, out-migrations, and permanent exits (including deaths).


While the average cascade score increased over time in all clusters, that increase was limited due to population dynamics, the total contribution of all population entries and exits being negative. Permanent exits and individuals already infected when reaching the age of 16 had a marginal effect. Although migrants had a lower position than the rest of the population, their overall impact on the cross-sectional population cascade remained limited as in- and out-migration compensated each other.


In a context of high HIV incidence, the continuous flow of newly infected individuals slows down the efforts to increase ART coverage and population viral suppression.


Larmarange Joseph, Diallo Mamadou Hassimiou, McGrath Nuala, Iwuji Collins, Thiébaut Rodolphe, Tanser Frank, Bärnighausen Till, Pillay Deenan, Dabis François, Orne-Gliemann Joanna and ANRS 12249 TasP Study Group (2018) “From inspanidual care trajectories to HIV care cascade at population level in rural KwaZulu-Natal (South Africa): the impact of population dynamics” (communication orale), presented at the Life History Research Society Conference, Paris.