Methodology
Estimating the Impact of a 3-Month Treatment Interruption for 15 Million People on HIV Treatment
Estimating total lifetime deaths associated with viremia over a 90 day period
What would happen if 15 million people who receive antiretroviral therapy (ART) through PEPFAR experienced a 3-month pause in treatment? This approach is similar to that taken in our previous work [1] and work we've advised on [2]. Here's how we arrived at our estimates:
Impact on Health:
A pause in treatment leads to people living with HIV having unsuppressed viral loads, which we know increases health risks over a lifetime, as well as contributes to onward transmission of HIV. On average, each year of being unsuppressed is associated with losing 2.45 healthy life years (DALYs) (range 1.35-3.55) [3]. Often we 'discount' future health effects to get a better understanding of how the impact relates to today. When we discount DALYs at 3% per year (often used in economic analyses), this would result in losing 1.47 disability adjusted life years for each person-year spent not on treatment (range 0.52-2.41) [3]. This adjusted figure is what we have used in our primary analysis.
For 20 million people, being unsuppressed for these 3 months could result in an average of a discounted 5.6 million healthy life years lost (with a range from 2.0 million to 9.1 million).
Deaths Estimated:
To make DALYs more intuitive, we translated these lost healthy life years into an estimated number of deaths. Assuming the average person living with HIV is 40 years old and would have otherwise lived to 61 (when discounted at 3% per year, this results in 15 DALYs), this translates to a discounted 370,000 deaths on average (ranging from 130,000 to 605,000) in the worst-case scenario. (Number of DALYs divided by 15)
This highlights the catastrophic consequences of even short-term interruptions in HIV treatment at scale and underscores the importance of ensuring continuous access to life-saving ART.
Estimating infant deaths associated with mother to child transmission of HIV and no access to antiretrovirals during the 90-day period
Unlike the long-term impacts of viremia, there are both immediate impacts of vertical transmission as well as long-term. We used estimates from amfAR on the number of infants expected to be born with HIV during the 90-day period as a result of this PEPFAR funding gap (approximately 26,000 infants). We then assumed that the infants would be born uniformly between day 1 and 90. Of the infants born with HIV that are not treated for their infection, 20% will die within the first three months of life [4]. For this calculation, assuming the midpoint of the three-month period, we assume that 10% of infants born during this 90-day window will die due to lack of access of PEPFAR-procured antiretroviral treatment. For infants that survive the period without PEPFAR-funded treatment, we assume they access treatment and are assigned 7.5 DALYs associated with their lifetime infection. Similar to above, we then aggregate across immediate deaths and longer term DALYs to estimate the total long term number of premature deaths associated with these 26,000 infant infections: 7,700 deaths (ranging from 6,600-8,500) including the 2,600 immediate deaths during the 90 day period.
Economic impact of PEPFAR funding
The economic impact of health gains can roughly be described as: for every life year saved, one times the GDP per capita will be generated within a respective country [1]. To understand this economic impact, we estimated the number of life years saved per year per country since the inception of PEPFAR. This has leveraged data from UNAIDS [5], GDP per capita data from the World Bank [6], and an assumption that ±43% of the HIV funding in the countries analysed has come from PEPFAR. We then took the total economic value of those life years saved and subtracted the total PEPFAR investment ($110 billion) to estimate the net economic gain- a total of $375 billion as of the end of 2024.