Are There A Lot Fewer Americans With HIV Than We Think?

A new study brings CDC estimates into serious question.
From: NewNowNext

 A new study suggests there are fewer Americans living with HIV than originally believed, and more of them are successfully using anti-retroviral drugs to suppress the virus.

According to the CDC, there are approximately 1.2 million HIV-positive people in the U.S., 86% of whom have been diagnosed.

Of those, 40% are reviving regular medical care, just 37% are on anti-retroviral meds and only 30% have undetectable viral loads.

 But a report published in the Journal of Acquired Immune Deficiency Syndromes (JAIDS), claims an estimate of only 819,200 Americans with the virus. Of that number, 86% have been diagnosed, and a whopping 72% are receiving care. More notable, 68% were on anti-retroviral meds—almost twice the CDC estimate—and 55% are undetectable.

That would seem to be good news—the more people receiving treatment and the more people with undetectable viral loads, the less HIV can spread. Right?

But, as POZ magazine points out, if the nation’s leading health organization is way off in its estimates about one of the most serious medical issues of our time, it’s a problem.

“The CDC method risks overestimating the number of [people] living with HIV/AIDS if duplicate cases were not identified… and deaths were missed by routine death registry matches,” says Dr. Qiang Xia of the New York City Department of Health and Mental Hygiene (DOHMH) and the lead author of the study. “Our method is not subject to these limitations and provides a more accurate estimate of the number of persons diagnosed with HIV.”

 So, how did we get two different sets of stats?

To estimate the number of people living with diagnosed HIV in 2011, the CDC researchers used HIV case reporting data, counting all those who have tested positive for the virus and who were not known to have died by the end of that year. To avoid artificially inflating the HIV-diagnosed population, surveillance researchers attempt to “deduplicate” records; but this process is by no means foolproof.

Xia and his team relied on HIV laboratory reporting data to make their own estimate of the size of the HIV-diagnosed population. First, to measure the number of people in care for the virus, they looked at reports from New York City and 19 other jurisdictions, counting as in care all those who had at least one CD4 and viral load test in 2011.

Next, they relied on observed patterns of individuals who were lost to and later returned to HIV care in order to extrapolate the number of those not in care during 2011. Then they added that figure to their estimate of the in-care population to arrive at an estimated number of people diagnosed with the virus. Last, to estimate the total HIV population, they presumed an 86 percent diagnosis rate, just as the CDC has, and extrapolated accordingly.

To arrive at their own estimate of the number of people with HIV who were retained in care in 2011, the CDC researchers looked at a sample of individuals who had at least one HIV care visit between January and April 2011.

Experts seem unsure which data to put their trust in.

“Are we really only 30 percent virally suppressed in this country?” Dr. Jennifer Kates, director of global health and HIV policy at The Kaiser Family Foundation, asked POZ. “We know that in some cities it’s much higher than that. Is [the national figure] as high as 55 percent? I don’t know the answer to that.”

Getting to the right number is essential—not just in understanding how to allocate resources, but to accurately predict how certain interventions will work.

The CDC estimates, for example, that use of PrEP could slash the rate of new HIV infections by 20% in five years—but that’s based on its assumption that only 30% of carriers are virally suppressed. If it’s more like 55%, we should see less of a decline.

For its part, the CDC promises it will release updated information later this year.