Monitoring Viral Load in HIV Infection

Joseph Eron, MD: How do you monitor someone, Colleen, once you start them on therapy?

Colleen Kelley, MD: Basically, I’m going to be monitoring their viral load. If we’re starting with one of these highly potent regimens, their viral load is going to drop very quickly in a matter of weeks.

Joseph Eron, MD: That’s so critical, right? A matter of weeks.

Colleen Kelley, MD: It used to be months. You would just watch people and wait for their viral loads to come down. Now, you can check them at 2 weeks, 4 weeks, and many people will already be undetectable—depending on how high they start with their viral infection.

Joseph Eron, MD: And if you don’t see that, something’s happened.

Colleen Kelley, MD: That’s worrisome.

Joseph Eron, MD: Maybe they didn’t go to the drugstore and pick it up? Sometimes, this happens. I’ve certainly had that happen. They’re not taking it as they should. Even like Eric mentioned with PrEP [pre-exposure prophylaxis], sometimes you believe they’re taking it like they should, but they’re actually not. This has happened to me. Sometimes a drug interaction is either unanticipated or not actually queried about. That can happen. By 2 weeks, you should see a 10- to 100-fold drop. What are your expectations in terms of CD4? How does that usually go?

Colleen Kelley, MD: CD4 is traditionally much longer in responding. I tell my patients that the CD4 count is on a months-to-years timeframe, depending on where you’re starting. So, we focus a lot less on CD4 count. For those people who are newly starting on therapy, we focus a lot on the viral load and getting that viral load to undetectable. That’s where their health is going to improve, regardless of what their CD4 count is.

Joseph Eron, MD: Are there people who you’re particularly worried about, who start therapy? You mentioned the people with advanced disease?

Daniel Kuritzkes, MD: Yes. The older you are, the lower your CD4 count when you start. The sicker you are, in terms of HIV disease, the smaller the increase in CD4 count. And for people who start with really low CD4 counts, less than 50, a reasonable proportion of them are never going to get above 200. They may continue to need prophylaxis to prevent opportunistic infections. We don’t fully understand why that is—that they don’t reconstitute their T-cell counts the way we’d like them to but they are still potentially at risk. That’s another reason why it’s so important to be doing active screening and to get people on treatment as soon as possible.

Colleen Kelley, MD: But even with a low CD4 count, their health is infinitely improved with a suppressed viral load. I take care of a lot of people with very low CD4 counts, so that’s what we focus on.

Eric Daar, MD: Yes. I think the biggest change in the guidelines over the last several years is, as said, less is more.

Joseph Eron, MD: In terms of testing?

Eric Daar, MD: Yes. For that subset of people who are really doing well, who have CD4s of over 500, who maintain viral suppression, the guidelines say, “Follow-up CD4 testing is optional,” because it will never change what you’re going to do in that setting. They hedge a little bit in the 300-to-500 group and say, “In this group, you may be able to test once a year if they’re maintaining viral suppression.” The likelihood that they’re going to drop below 200 and need prophylaxis is low in that setting. So, we’re doing less and less CD4s because they’re less meaningful once somebody has a high count and doesn’t need prophylaxis, as long as their virus is suppressed.

Then, we’re also doing less and less viral load testing. We used to do it every month, every 3 months, every 4 months, because we were desperately waiting for people to fail and we know that people who do well will continue to do well, unless something changes. Now, the guidelines are starting to say, in that patient who has been virologically suppressed for a couple of years, every 6 months may be plenty. You could even argue for less than that. We have patients who don’t show up. They miss all of their appointments. They come in once a year. They’re always undetectable.

Daniel Kuritzkes, MD: I think it really depends on the patient and the relationship with the patient. From a medical perspective, you certainly could be monitoring virus loads as infrequently as once a year. But there are some patients who really need that contact with their HIV therapy provider. Seeing them on a quarterly basis to tell them that their virus load is still suppressed is such a positive reinforcement for continued adherence. So, I think you have to judge who the patient is and what’s going to work best for them.

Joseph Eron, MD: I haven’t yet encountered a patient who wants to completely give up testing their CD4s.

Daniel Kuritzkes, MD: Yes.

Joseph Eron, MD: I get it. It’s in the guidelines. I haven’t quite gotten to the person that says, “OK, never test it again. That’s fine.”

Eric Daar, MD: In none of those people do we do anything other than tell them that the drop from 600 to 500 is not relevant.

Transcript edited for clarity.