Why getting regular HIV tests is good for your health

 

We’ve all heard the message: GET TESTED!

For those of us who aren’t HIV positive, getting a regular HIV test is the only way to be sure that we’re negative. It’s generally recommended that we get tested at least twice a year to best be informed about our status. However, not everyone (in fact, probably most people) don’t get tested that regularly.

Luuk Gras and colleagues reported on their ATHENA study in the most recent issue of the journal AIDS.

A little off-topic, but ATHENA is one of those funny acronyms that sort of cheat a little and use letters other than just the first letter of each word. It stands for AIDS THerapy Evaluation in the NetherlAnds.

Anyway, the authors were concerned about how late some people are getting an HIV diagnosis. They feel that these late diagnoses are the main reason that life expectancy for people with HIV is still lower compared to the general population, since so many people are getting that diagnosis too late, after HIV has already done some serious damage.

Life expectancy is much higher for people with an early HIV diagnosis, and actually approaches the life expectancy of the general population.

They wanted to show that it was in fact better to get tested for HIV more often than it was to get tested less often. I was surprised a study like this hadn’t actually been done before, and so were they. From the article: “Although seemingly obvious, it has never been demonstrated that patients who were repeatedly tested for HIV before testing positive have a better clinical prognosis than patients who initially tested positive”.


Who were the study participants?

The study looked at almost 5500 patients who got a positive HIV test in the Netherlands between 2004 and 2008. For some reason, they only included people who reported getting infected through sex, so the study group didn’t include people who inject drugs. They divided these patients into three groups:

• People whose first-ever HIV test was positive (meaning it’s unknown when they got infected). I’ll call them “First-time-testers”

• People who last had a negative HIV test 1 to 2 years before, and then tested positive

• People who had last tested negative less than a year before, but who now tested positive (most frequent testers)

What this allowed the researchers to do was split people into how frequently they got an HIV test (bad, better, best) and compare them at the time they were diagnosed with HIV and how they fared over time.


There were differences among the groups

Of the 5494 patients studied, WAY too many tested positive on their first-ever HIV test (almost 3 in 4). In comparison, 10% of patients were in the group that was infected within the past 1 to 2 years, and 16% were regular testers who were infected within the year.

There were some interesting differences between these groups. More of the first-time-testers, were immigrants to the Netherlands (mostly from Sub-Saharan Africa), and there were more women and more people who got HIV through heterosexual transmission compared to the other groups. In contrast, the more frequent testers were more likely to be men who have sex with men (MSM) and were overall slightly younger than those who were first-time-testers (34.7 versus 36.0 years old). This group was getting tested about every 6 months on average.

To me, all this seems to indicate that gay men, including younger guys, are definitely getting the message that they should be getting frequent HIV tests. However, there are some groups that for some reason are not testing as regularly as they should. Women were overrepresented in the people whose first-ever HIV test came back positive. So were immigrants to the Netherlands, and heterosexual people. This seems to call for some increased targeting of these groups of people who are still at risk but aren’t getting tested as often as they should.


What was the effect of testing frequency on health?

So, did getting tested more frequently improve the health of people when they actually got infected? Yes.

As we know, HIV targets a part of the immune system called CD4 cells, which die over time in people with HIV who aren’t on treatment. These cells are important in coordinating the immune system response, and when they dip below 200 cells per cubic millimetre (about the size of a drop of blood), that’s when you run the risk of opportunistic infections that healthy immune systems can usually fight off. In fact, a CD4 cell count below 200 is what’s known as an “AIDS-defining event”, meaning it automatically triggers a diagnosis of AIDS by a doctor.

Patients who tested most frequently had much higher CD4 counts than those who tested less frequently. They started off with 550 cells at diagnosis versus only 350 in the first time testers. Almost half of first-time-testers had a CD4 count below 200, versus only about a quarter of those receiving tests within one year. Basically, this says that by getting tested frequently, HIV has less time to do its damage to our immune systems before we get a positive diagnosis. This makes sense. Getting tested more frequently means that we can catch our infection early if we do end up testing positive.

The most frequent testers were far less likely to be diagnosed with AIDS when they tested HIV positive (1.5% versus 16% in the patients whose first HIV test came back positive).

Most importantly, patients who tested more frequently were way less likely to die than those whose first test was positive. Frequent testers had about half the risk of death compared to the first-time-testers. That’s a big effect just from regularly keeping up to date on your HIV status. The lower death rates are probably due to fewer AIDS diagnoses and better CD4 counts, both indicating healthier immune systems.

The authors even propose that this lower risk for death may even be higher than what their numbers show. That’s because the first-time-testers were more likely to be “lost to follow-up” than the other patients, meaning basically that they couldn’t be located or contacted anymore. The authors found that people with lower CD4 counts were actually more likely to be lost to follow-up than people with higher CD4 counts. Since having a low CD4 count puts someone at a higher risk of death, it’s likely that a lot of people who were lost to follow-up actually died without the authors finding out. That means that the number of first-time-testers who died may have been underestimated, and so more frequent testers may have an even lower risk of death compared to that population.


All in all, getting regular HIV tests means that if we do end up getting a positive result, we’ll be healthier and have a lower risk of dying. Sounds good to me.

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