Background: It is hoped that eliminating CD4 count thresholds for ART eligibility will increase the number of HIV-infected persons receiving therapy and reduce transmission of HIV. However, little is known about the impact of relaxing eligibility thresholds on uptake of ART.
Methods: Clinical records were analyzed for all patients presenting for HIV care in the Hlabisa sub-district public sector ART program. We estimated the distribution of first CD4 counts for patients presenting in 2013 (Figure, left). We then estimated the conditional probability of ART initiation within six months for each CD4 count under two counterfactual states of the world (Figure, right): if CD4-eligible and if not CD4-eligible. Multiplying the conditional probabilities by the distribution of CD4 counts, we estimated the probability that a person would initiate ART under expanded guidelines (CD4< 500, or elimination of CD4 criteria) and under older guidelines (CD4< 350). We forecast the number of new initiators expected if South Africa adopts new WHO recommendations.
Results: In 2013, 20.0% of patients presented at 350-500 cells and 38.9% >500 cells. 8.4% of patients 350-500 cells and 8.0% of patients >500 cells would have initiated ART under the old guidelines. 29.7% of patients 350-500 cells and 19.2% of patients >500 cells would initiate ART if CD4 criteria were eliminated. 62.1% of patients at 350-500 cells and 72.8% > 500 cells are not expected to initiate under expanded guidelines despite being eligible. If these numbers hold nationally, then South Africa can expect 130,000 additional initiators per year from raising the threshold to 500 and a further 164,000 initiators per year from eliminating CD4 criteria, representing a 5% increase in persons on ART.
Conclusions: Removing CD4 criteria alone, without improving HIV testing, linkage, and ART initiation procedures, will not achieve the country''s 90-90-90 targets.

Figure. Distribution of first CD4 counts and probability of starting ART at different CD4 counts.
[Figure. Distribution of first CD4 counts and probability of starting ART at different CD4 counts.]