In addition, countries will need to think very carefully about the resource implications of a move to earlier treatment, since current estimates of the numbers of symptomatic people with HIV – those in WHO stages 3 and 4 and therefore already eligible under most national guidelines– may need to be raised as a result of recent refinements of HIV prevalence estimates.
Previous estimates of the numbers requiring treatment were based on a life expectancy estimate of two years after becoming eligible for antiretroviral treatment. The UNAIDS Reference Group on Estimates, Modelling and Projections recommended that this period should be increased to three years, and that the time from seroconversion to death in the absence of antiretroviral therapy should be revised from 9 years to 11 years, and that the time from seroconversion to antiretroviral therapy eligibility should be revised from 7 years to 8 years
Prof. Charlie Gilks told the HIV Implementers’ Meeting that the numbers eligible for treatment according to current guidelines are likely to be 30% higher than previously estimated despite the declines in HIV prevalence estimates for some African countries that were also a result of the epidemiology review, and an increase in the threshold for starting treatment to 350 cells would see the numbers in need of treatment grow by 50%. Countries currently showing strong progress in achieving high treatment coverage could post less encouraging results in the future.
“You will see your coverage dropping by 50% [if the threshold for treatment is raised to 350]. This will be catastrophically undermining unless you prepare your president, your minister of health, your press,” he told the meeting.
The World Health Organization is currently engaged in revision of its treatment guidelines, and part of that process will be scenario modelling of the costs of different national approaches, using varying thresholds for treatment and first-line drug regimens.
He said that more information on the quantifiable advantages of treatment at 350 cells/ mm3 would be needed in order to persuade policy makers of the need for change at national level.
A modelling exercise comparing the effects of starting treatment at a CD4 count of 350 or at the current thresholds laid out in South African guidelines, using a d4T-based regimen, found that treatment costs would be increased by $13 billion over five years, but that indirect costs (GDP lost due to early loss of life) would fall by $61 billion, and that earlier treatment was highly cost-effective for the South African economy.15
A mathematical modelling exercise by researchers at Imperial College, London, suggests that CD4 cell monitoring and initiation of treatment at a threshold of 350 cells, together with a much greater frequency of HIV diagnosis, would have the most substantial impact on mortality in sub-Saharan Africa. However the study also found that earlier treatment would have significantly less impact on mortality if it was not accompanied by a much higher rate of HIV diagnosis.
Speaking during the rapporteur session at the close of the HIV Implementers’ Meeting, Dr Francois Venter suggested that the short-term effect of changing the threshold would benefit only a limited number of patients at first.
“Starting CD4 cell counts are usually very, very low, so in fact, increasing the threshold is unlikely to make a huge impact in terms of the number of people or what CD4 cell count they actually are initiated at," he told the conference.
Offering treatment to those already in care but not yet eligible for treatment may be the best way to retain those people in treatment, and a number of speakers at this year’s HIV Implementers’ Meeting expressed concern about the ongoing difficulties that treatment programmes face in retaining untreated people in care.
“The hidden part of loss to follow-up is the people who are eligible for all other care but antiretroviral therapy,” said Diane Noble of the Clinton Foundation. Loss to follow-up in this patient group is not as well quantified as in those who have started treatment, and those lost to follow-up are not flagged as in need of investigation in the same way as those already on treatment.