AIDS/HIV | Health | Truvada

'New York Times' Explains Conflicting Truvada Effectiveness Stats

The New York Times has published an insightful, data-driven rundown clarifying the sometimes conflicting information concerning Truvada that’s in circulation.

IPrEx_OLE_logoThe primary point of contention, writes Josh Barro, is linked to Truvada users actually taking the drug consistently, the way it’s prescribed. iPrEx, the first large scale, randomized PrEP trial using human subjects, found that Truvada users were 44% less likely to test HIV positive at the end of the trial compared to participants given a placebo. Participants who didn’t consistently take the drug, however, did not display the same immunity:

Of 48 iPrEx subjects who were assigned to take Truvada and contracted H.I.V. anyway, just four had any detectable level of the drug in their system when they were diagnosed, indicating a 92 percent reduction in risk for people who were actually taking the medicine.

But wait, there’s more: Those four subjects who took Truvada and became infected had its active ingredients in their blood only at levels consistent with taking the drug twice a week. That is, in the study, there were zeroapparent cases of subjects taking their pills daily and contracting H.I.V.

iPrEx’s sample size was relatively small sample size of 2,500 people and the fact that only 18% of participants were shown to have taken the drug daily made it difficult for researchers to claim 100% efficacy.

But by looking at the handful of infections among people taking their pills less than daily, the iPrEx researchers were able to build a statistical model of how the risk of infection declines as the number of pills taken weekly rises. In 2012, they estimated that actually taking Truvada every day produces a 99 percent reduction in the risk of H.I.V. infection, despite not directly observing any such infections.

The general consensus within the HIV/AIDS research community is that Truvada is, in fact, helpful in the prevention of contracting the, but doctors remain wary of putting a precise percentage on current studies.


Read through a an in-depth iPrEx fact sheet AFTER THE JUMP...

iPrEx Fact Sheet: About the iPrEx Study

 

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Comments

  1. This seems a little "ignore the man behind the curtain", I'm keenly aware how statistics are used is drug trials but this explanation seems to be accounting for compliance and human nature, both things we are usually instructed to ignore/mitigate during our trials...different standards maybe?

    Posted by: Epic | Jul 18, 2014 8:12:26 AM


  2. $400 month co-pay. Rubbers and viagra are cheaper.

    Posted by: Qj201 | Jul 18, 2014 8:19:33 AM


  3. @ QJ201 - it sounds as if you won't need the rubbers if you skip the Viagra.

    Posted by: Mike in the Tundra | Jul 18, 2014 8:33:17 AM


  4. From the link above...

    "The other big finding of the trial was that while 93% of trial subjects reported taking the pills correctly, on the basis of drug-level monitoring in blood tests only 51% actually did so. The investigators calculated that if participants had taken their pills every time, the efficacy of the drug regimen would have been at least 92%, compared with a placebo."

    Umm, we can't know this as only 51% took the regime correctly but they didn't test everyone randomly or consistently they only tested a self selected group. Unless they tested a statistically significant portion of the group for compliance they can't really claim existence of a group they fabricated.
    "
    The researchers estimated adherence on the basis of the number of pill bottles dispensed and empty ones returned, and via self-report – though, as discussed below, this turned out not to be a reliable indicator of adherence. Average adherence reported by study subjects on this basis was between 86 and 95%, depending on whether pills in unreturned bottles were regarded as having been taken or not. In subjects reporting greater than 50% adherence, the efficacy of tenofovir/FTC was 50%. In subjects reporting over 90% adherence, efficacy was 73%."

    How did they arrive at 95% efficacy when the highest level of adherence could only have achieved 73% ? Why would you take a prophylaxis that was only effective if it was taken while using condoms?? Seems like an incredible waste of money that could be much more effectively used then satisfying white/rich guilt, because they're not providing this to brown people as any sort of service.

    Truvada is a great drug, this seems like a awful cash grab...oh well.

    Posted by: Epic | Jul 18, 2014 8:37:09 AM


  5. With this kind of compliance in a larger population engaged in unprotected sex with multiple partners, welcome to an emerging drug-resistant HIV virus. This is nuts, absolutely nuts.

    Posted by: Anonymous | Jul 18, 2014 8:47:19 AM


  6. I'm sorry I hate to beat dead horse but this is starting to become absurd

    "But by looking at the handful of infections among people taking their pills less than daily, the iPrEx researchers were able to build a statistical model of how the risk of infection declines as the number of pills taken weekly rises. In 2012, they estimated that actually taking Truvada every day produces a 99 percent reduction in the risk of H.I.V. infection, despite not directly observing any such infections."

    "build a statistical model" and "despite not directly observing any such infections" seem to combine and form "because we said so, and magic". They first can't directly attribute "the number of pills taken every week" because only 51% were compliant, and the number that they did test for compliance would invalidate the significant members of that population of the study to the point were they had participants numbered in 10s of people, not 2400...

    Posted by: Epic | Jul 18, 2014 9:02:22 AM


  7. a % of "severe liver problems" developing would have been nice as well

    per truvada's own website and there exact words = "SEVERE LIVER PROBLEMS"

    no transplant (which takes a long time to get) = death when the liver goes

    Posted by: Moz's | Jul 18, 2014 9:38:14 AM


  8. Well, at this point it's clear that this could be a way to end the AIDS epidemic. Men who have anal sex with men should be required to be put on this, so they can't go on and infect each other, and occasionally even the rest of us who are saner and don't engage in questionable practices like anal sex.

    Posted by: Pandion | Jul 18, 2014 9:50:21 AM


  9. "the rest of us who are saner and don't engage in questionable practices like anal sex."

    Sweetie, you keep telling yourself it's your choice, and not because no one would fvck yo' ugly ass.

    Posted by: crispy | Jul 18, 2014 10:00:16 AM


  10. Example of pharmaceutical marketing gone awry so I decided to read the actual research paper published in NEJM.


    Interesting point:

    High-risk sexual behavior was substantially DECREASED in all participants of the study. This means decreased barebacking and multiple sexual partners. Why? Because the participants did not know which group they were in --placebo vs Truvada. The authors of the study worried that if the word got out and Truvada becomes the sole means of safe sex, high-risk sexual behavior might increase and the true effectiveness of Truvada will be tested.

    Bottom line, no one knows the true effectiveness of the drug yet, unless you do a study where the entire cohort practice only unprotected sex and then compared the placebo vs drug groups. However, such study is unlikely due to the unethical nature of it.

    Posted by: philip | Jul 18, 2014 10:20:49 AM


  11. interesting point philip

    Posted by: Moz's | Jul 18, 2014 1:00:14 PM


  12. @epic Compliance and human nature aren't relevant when you're looking at the effectiveness of a drug pharmacologically, but they're very, very relevant when your looking at its effectiveness as a public health strategy.

    Posted by: Distingue Traces | Jul 18, 2014 6:21:09 PM


  13. Sorry, but is just don't buy PrEP as a better solution to condoms. I'd far rather use a condom only when needed as opposed to popping a pill daily that has scary side effects, is far more expensive and is difficult to maintain a consistent regimen. A condom can't protect you from everything, but it protects you from more than just HIV and you KNOW when you or your partner is using it, as opposed to trusting that they are on PrEP or that you have used it properly. Until there's a real cure, use a condom, folks.

    Posted by: graphicjack | Jul 18, 2014 9:00:22 PM


  14. Compliance comes with difficulty even to diagnosed population. I take Truvada once a day, have been poz for 23 years. The regimen has changed, but compliance coupled with improved self management of health, as opposed to "risky behavior" modification, lol, have helped me survive and thrive. Liver damage mans someone is still drinking, not ODg on Truvada. Be real.

    Posted by: chevytexas | Jul 18, 2014 10:54:46 PM


  15. I was in the clinical trial of Truvada that led to the approval of PrEP, and I would like to take it now but I can't. Truvada is an extremely expensive drug which few would be able to afford if it were not for subsidized pricing for some -- but not all -- people below a certain income level. Those who are ineligible for subsidized Truvada are men receiving Medicaid or Medicare, and I'm one of them. What can be done to end this irrational and harmful discriminatory practice?

    Posted by: Stuart | Jul 18, 2014 11:58:49 PM


  16. @GRAPHICJACK. I don't think anyone is saying that PrEP is better than condoms. It's intended to be a way to deal with the fact that many people - for whatever reasons - have anal sex without condoms. Those advocating for PrEp are saying it is better than unprotected sex in helping prevent the spread of HIV.

    Posted by: David | Jul 19, 2014 12:15:06 AM


  17. @ chevytexas

    check truvada site the company that makes it=gilead sciences, own website states nothing about drinking but just taking truvada risks

    "sever liver damage"

    http://www.truvada.com/truvada-side-effects

    believe your own eyes and the company that makes it

    Posted by: Moz's | Jul 19, 2014 1:23:25 AM


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