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Summary:

The preprint “Excess HIV infections and costs associated with reductions in HIV prevention services in the United States: Projections using real-world-data” seeks to estimate the impact of decreasing PrEP coverage in the United States in response to looming funding cuts. PrEP (pre-exposure prophylaxis) is a highly effective way of reducing a person’s risk of acquiring HIV.

The preprint builds on previously published work connecting ecological data on PrEP coverage to HIV diagnosis rates. The authors estimate that an annual reduction of 3.3% in PrEP coverage over the next decade would lead to 8,618 new HIV infections that would have otherwise been averted, incurring additional lifetime medical costs of $3.6 billion (discounted) and $9.3 billion (undiscounted). Though there is significant uncertainty in this estimate, it is likely very conservative as the authors do not include secondary HIV infections arising from unaverted infections. The 3.3% annual decrease in coverage was chosen as a decrease of this size, over the next decade, would reverse the past decade’s hard-won progress in PrEP coverage. This preprint’s findings and message are urgent; its methods are robust enough to support its broader claim. It is publishable with few edits.

Major Issues

1. The preprint uses a regression model, with new HIV diagnoses as the outcome and an ecological measure of PrEP coverage as a continuous predictor. In adapting the model for this analysis, the authors assume that decreasing PrEP coverage would have an equal and opposite effect on HIV infection rates as increasing PrEP coverage. While consistent with the model, this assumption should be explicitly addressed in the discussion. 

   While this assumption introduces some bias into the model, the model provides relevant guideposts for what we can expect to see under a regime of decreased PrEP funding. The author’s estimates are biased in a conservative way by their exclusion of secondary HIV cases arising from those who would otherwise not have been infected.

2. The preprint performs sensitivity analyses of PrEP coverage decreasing by 2% annually or by 10% annually, which are described as low- and high-impact scenarios. A clear justification of the rationale for selecting these values is needed.

Minor Issues

1. In Table 1, the title box stating, “HIV infections not averted” should be broadened, so as not to cut “infections”. 

2. Table 1 would benefit from a column indicating net-lifetime costs, as net-lifetime costs are more extensively discussed in the preprint than “net cost over 10 years”.

Recommendations/Possible Extensions

1. The preprint may be strengthened by providing a conservative estimate of how much funding to PrEP related programs would need to be cut to arrive at a 3.3% annual reduction in coverage over the next decade.

2. Core to the author’s argument is that decreasing funding for PrEP would lead to greatly increased human- and healthcare-cost. In Table 1, they present net-costs over a decade arising from unaverted cases due to decreasing PrEP coverage. The preprint would be strengthened by more strongly highlighting these net costs, as these estimates undermine any financial-efficiency argument for cutting funding to PrEP. 

3. The point made in 2) could be supported further by including net-lifetime cost estimates in the preprint’s analysis. 

4. This preprint is published in direct and urgent response to funding cuts that would affect PrEP coverage and HIV prevention, including those to NIH, and CDC. While unusual, I believe that this preprint would benefit from a more explicit discussion of these funding cuts, as well as more extensive citations of news sources covering these developments. These may form an important part of contextualizing the preprint’s research. (Examples may include What Does the Future Hold for the Ending the HIV Epidemic Initiative (EHE)?, KFF or Trump Administration Dialing Back Support for H.I.V. Prevention, NYTimes)

5. We agree that the preprint should be published as soon as possible, as part of a greater argument in defense of spending on PrEP and preventative measures more generally. While much energy should be directed towards preventing funding cuts, future work may estimate how best to apply more limited public or private funds for HIV prevention.

Competing interests

The authors declare that they have no competing interests.