Doxy PEP Offers Alternative To Condoms

[Simon Suraci]

1 hour ago, Simon Suraci said:

and advisable considering your particular body and overall health

@Unicorn I acknowledge it’s not for everyone. Some people’s bodies can’t tolerate PrEP. There are side effects for some people, albeit a minority.

[SirBillybob]

20 hours ago, mike carey said:

I'm replying to the maths (or statistics) not the effectiveness of PrEP. No, a probability of 99% does not mean that in every set of 100 instances the event (in this case infection) will occur. It means that every time there is a 1% chance of it happening, including the 100th. Probability is calculated by a large number of observations and does not indicate that the event will occur regularly every n instances. Think of tossing a coin. There is a statistical probability that it will fall as a head on 50% of instances, but we know that that doesn't happen every second throw.

These estimates can be calculated using the “probability of at least one” algorithm.

For 1/100 chance per event, 100 events produces a 63.4% likelihood of minimally one occurrence.

For the actual HIV risk estimate of 1/72 per event, 72 events produces a 63.8% likelihood of minimally one infection transmission; 100 events produces a 75.6% likelihood of infection transmission. 

Again, these figures relate to unprotected receptive anal intercourse with one or more ‘topping’ poz partners with detectable viral load. In Canada about one-quarter of people living with HIV have detectable viral load. 

Edited August 5, 2023 by SirBillybob

[nate_sf]

So back to the original post asking about Doxy PEP. Yes, it's been around for a while, but I think awareness has been increasing lately. A friend of mine mentioned it to me a few months ago, and the last time I saw my doc he suggested it before I asked about it. This was when I was doing my quarterly bloodwork and STI check, so it made sense that he'd suggest it in that context.

I also had the concern about the potential for mass long term use of various antibiotics may accelerate the development and spread of antibiotic resistant strains of STIs. Doc said he is not too concerned given the relatively low dosages of the antibiotic, and provided they are taken as advised (just after sex). Take that for what you will... maybe the doc is a shill for the pharmaceuticals, but I know he also keeps up with the medical journals so I trust his judgement. I'm not obsessing over or wanting to argue over statistics; instead my thoughts are if Doxy PEP can prevent or lessen the transmission of STIs, that's something I'm interested in.

[Rudynate]

On 7/30/2023 at 4:49 AM, pubic_assistance said:

Deterioration of kidney function in men over 50 is his major concern.

The stomach issues are more uncomfortable than dangerous.

Some liver damage reported but not common.

DESCOVY appears (thus far) to have fewer incidents than Truvada.

If they are monitoring  your serum creatinine closely the way the are supposed to be, they can catch it before it becomes permanent kidney damage. 

[Rudynate]

On 8/4/2023 at 6:53 AM, CuriousByNature said:

I'm definitely not a mathematician.  If PrEP is 99% effective, doesn't that mean if a person on PrEP has intercourse 100 times with positive partners who are not undetectable, it almost guaranteed they will contract HIV even if they are staying true to a PrEP regime?  Since PrEP is effective 99/100 times?

What is the incidence of infection if PrEP and condoms are used?  I don't remember how to calculate that properly.

 

No - it means that every time you have sex in the scenario you have described, there is a 1% possibility that you will become infected with HIV from that encounter.  The probablity doesn't carry over from one encounter to another - it resets with each encounter.

 

Edited August 6, 2023 by Rudynate
add content

[SirBillybob]

2 hours ago, Rudynate said:

No - it means that every time you have sex in the scenario you have described, there is a 1% possibility that you will become infected with HIV from that encounter.  The probablity doesn't carry over from one encounter to another - it resets with each encounter.

 

Well, no.

It is true that the single event probability is static and that probability is not influenced by successive exclusion, as in, say, lotteries where each ball number can only be drawn once.

A clinician would certainly not present the ‘reset’ idea to a HIV serodiscordant couple.

The probability does carry over in this context. 1% the first time, 1.99% combining 2 times, 2.97% combining 3 times, and as I wrote, 63.4% by the 100th time. Well, not literally 63.4% THE 100th time, but the aggregate of 100 events produces a risk of at least 63.4% overall.

Additionally, the higher the number of risk events the greater the chance of an unspecified number of additional infection events occurring, beyond 1, although only one infection event is basically relevant for probability purposes. Clinical factors related to multiple transmissions may pose additional implications. 

One can reverse engineer the formula to calculate the number of risk events that produces an arbitrary probability, say 10%. 

The formula contains an exponential component, so 20 times in total does not exactly double the risk of 10 times in total, and so on. In research we call this a nonlinear function.

One must account for successively avoiding the 1% single event undesired outcome. (Well, not successive in succession because the infection may occur prior to one of the events in the aggregate that did not transmit infection)

That is why during COVID peaks where infection transmissibility status was unknown the recommendation given for, say, 6 as opposed to 10 guests at a holiday dinner, or 6 as opposed to 10 1:1 lunches to carry less overall risk. 

Edited August 6, 2023 by SirBillybob

[Guest]

48 minutes ago, Rudynate said:

No - it means that every time you have sex in the scenario you have described, there is a 1% possibility that you will become infected with HIV from that encounter.  The probablity doesn't carry over from one encounter to another - it resets with each encounter.

I think 99% efficacy means 100X better than using nothing (99% reduction in risk). The actual odds for an unprotected bottom with one encounter is 1.4%:

 

Exposure type	Estimated infections per 10,000 exposures	Estimated risk for a single exposure
Receiving anal sex	138	1.4%
Insertive anal sex	11	0.1%

If PrEP being on PrEP meant a 1% chance of getting the virus with each encounter, then it wouldn't be doing much. Actually, being on PrEP means an under 0.014% chance per encounter. Of course, if you're an escort, having sex 200 times per year, the odds can still stack up pretty quickly, so adding the condom is wise. 

 

[Rudynate]

1 hour ago, Unicorn said:

I think 99% efficacy means 100X better than using nothing (99% reduction in risk). The actual odds for an unprotected bottom with one encounter is 1.4%:

 

Exposure type	Estimated infections per 10,000 exposures	Estimated risk for a single exposure
Receiving anal sex	138	1.4%
Insertive anal sex	11	0.1%

If PrEP being on PrEP meant a 1% chance of getting the virus with each encounter, then it wouldn't be doing much. Actually, being on PrEP means an under 0.014% chance per encounter. Of course, if you're an escort, having sex 200 times per year, the odds can still stack up pretty quickly, so adding the condom is wise. 

 

Odds are different from probability.  The odds of successful infection increase with the number of events, but the probability of infection from a single event is unaffected.   Having given this a little more thought, I can see that odds are a much more useful way of expressing the probability of infection.  But odds would only be accurate if each event was substantially identical.

[SirBillybob]

5 hours ago, Unicorn said:

I think 99% efficacy means 100X better than using nothing (99% reduction in risk). The actual odds for an unprotected bottom with one encounter is 1.4%:

 

Exposure type	Estimated infections per 10,000 exposures	Estimated risk for a single exposure
Receiving anal sex	138	1.4%
Insertive anal sex	11	0.1%

If PrEP being on PrEP meant a 1% chance of getting the virus with each encounter, then it wouldn't be doing much. Actually, being on PrEP means an under 0.014% chance per encounter. Of course, if you're an escort, having sex 200 times per year, the odds can still stack up pretty quickly, so adding the condom is wise. 

 

Odds are ratios. Just ask your bookie or the bored mechanical rabbit at the dog track.

Probability can be computed as an odds ratio and vice versa. 1.4% probability is odds p/(1-p): .014/.986, commonly depicted as .014:.986, but because odds are best depicted as x:1, more steps are required to find the multiplier, 71.43 in this case, to convert the ratio to 1:70.4 … It’s just faster to divide 100 by 1.4 to yield the chance 1/71.4 

In some cases chance is a better descriptor than probability. As @Unicorn correctly states, PrEP infection probability is reduced to .014%, but that may be less relatable compared to 1.4%. Therefore 1/7,144 chance of infection may be employed. At that high a figure an odds of 7,143:1 of NOT infection does not add much info. 
[I had mistyped 1/9,091 as opposed to 1/7,144 in an earlier post, edit window having expired]

Of course, chance is just an informal synonym for probability but I prefer not to use them interchangeably because probability has a defined range 0-100% or 0.0-1.0

Edited August 7, 2023 by SirBillybob

[SirBillybob]

8 hours ago, nate_sf said:

So back to the original post asking about Doxy PEP. Yes, it's been around for a while, but I think awareness has been increasing lately. A friend of mine mentioned it to me a few months ago, and the last time I saw my doc he suggested it before I asked about it. This was when I was doing my quarterly bloodwork and STI check, so it made sense that he'd suggest it in that context.

I also had the concern about the potential for mass long term use of various antibiotics may accelerate the development and spread of antibiotic resistant strains of STIs. Doc said he is not too concerned given the relatively low dosages of the antibiotic, and provided they are taken as advised (just after sex). Take that for what you will... maybe the doc is a shill for the pharmaceuticals, but I know he also keeps up with the medical journals so I trust his judgement. I'm not obsessing over or wanting to argue over statistics; instead my thoughts are if Doxy PEP can prevent or lessen the transmission of STIs, that's something I'm interested in.

Well, Doxy PEP certainly holds promise but bacterial STI drug resistance is a genuine concern that requires further investigation and has put most of the clinical world outside San Fran Health on greater pause. In fact, the known higher level of already existing gonorrhea tetracycline class resistance in France compared to USA is put forward as a possible explanation for the difference in some of the research findings regarding Doxy PEP impact between the two settings. 

Another important factor is the overall high gonorrhea incidence in trials for both treatment and control arms, compared to syphilis and chlamydia. One might be impressed by risk reduction figures but not be comfortable with the actual incidence rate of gonorrhea that nevertheless occurs on PEP, in spite of a small average handful of different partners. 

There may be some good news regarding the potential for gonorrhea infection risk reduction conferred by Meningococcal B vaccine, as it has shown significant effects on its own in research tacking it on to Doxy PEP study, I believe not yet assessed in combination. Unfortunately, just one small trial recruiting in USA at this time: in Chapel Hill, but with a urethral gonorrhea exposure challenge (!; I doubt a fun one, and the cohort upper age limit is decades below our median)

Therefore, global efforts may eventually involve a multi-pronged approach. That said, one major way to reduce incidence and prevalence remains via regular surveillance and diagnosis-centred treatment prn. If this were to be done assiduously the effects would be enormous. 

Edited August 7, 2023 by SirBillybob

[Luv2play]

On 8/5/2023 at 12:23 AM, Unicorn said:

I agree with the rest of your post, but, really, NO reason??

Possible DESCOVY for PrEP® Side Effects

WWW.DESCOVY.COM

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Learn about DESCOVY® (emtricitabine200 mg and tenofovir alafenamide 25 mg) tablets. See important warnings. DESCOVY.com

 

What are the other possible side effects of DESCOVY for PrEP?

Serious side effects of DESCOVY may also include:

• Kidney problems, including kidney failure. Your healthcare provider should do blood and urine tests to check your kidneys before and during treatment with DESCOVY. If you develop kidney problems, your healthcare provider may tell you to stop taking DESCOVY.
• Too much lactic acid in your blood (lactic acidosis), which is a serious but rare medical emergency that can lead to death. Tell your healthcare provider right away if you get these symptoms: weakness or being more tired than usual, unusual muscle pain, being short of breath or fast breathing, stomach pain with nausea and vomiting, cold or blue hands and feet, feel dizzy or lightheaded, or a fast or abnormal heartbeat.
• Severe liver problems, which in rare cases can lead to death. Tell your healthcare provider right away if you get these symptoms: skin or the white part of your eyes turns yellow, dark "tea-colored" urine, light-colored stools, loss of appetite for several days or longer, nausea, or stomach-area pain.

Common side effects in people taking DESCOVY for PrEP are diarrhea, nausea, headache, fatigue, and stomach pain. Tell your healthcare provider if you have any side effects that bother you or do not go away.

Common side effects for DESCOVY

The results were analyzed when everyone had been in the study for at least 2 years (~96 weeks). At that point, common side effects† included:
	DESCOVY	TRUVADA
Diarrhea	5%	6%
Nausea	4%	5%
Headache	2%	2%
Fatigue	2%	3%
Stomach Discomfort‡	2%	3%

 

Bear in mind that the above side-effect rates were from those who stuck in the study for at least 2 years. It does not include those who quite earlier due to side-effects.

Most people over the course of two years will suffer from one or more of those side effects in any event. Headaches? Diarrhea? Fatigue? 

So how do they know it is caused by their taking PreP? In those stats, is the condition chronic if on PreP?

[Guest]

51 minutes ago, Luv2play said:

...

So how do they know it is caused by their taking PreP? In those stats, is the condition chronic if on PreP?

Drug manufacturers are only required to disclose side-effects which are significantly more common with the medication than with the placebo. As with all approved medications, approval is given only if there are double-blinded placebo-controlled randomized clinical studies to back up the safety and efficacy. (Neither the researchers nor the patients know if they are getting the medication or the placebo)

[pubic_assistance]

On 8/6/2023 at 1:44 PM, Rudynate said:

If they are monitoring  your serum creatinine closely the way the are supposed to be, they can catch it before it becomes permanent kidney damage. 

I'm not on PreP. So no monitoring necessary. Condoms work just fine for me as a top.

 

[Rudynate]

1 hour ago, pubic_assistance said:

I'm not on PreP. So no monitoring necessary. Condoms work just fine for me as a top.

 

But you offered that as one of your reasons not to go on PrEP.

[pubic_assistance]

Yes 

I am following the recommendation of my Doctor. 

Saying there is no monitoring necessary because I chose to avoid the risks of PreP in favor of continuing to use condoms. ( If I were a bottom I might think differently). 

[+ Lucky]

A friend was told that Medicare does not cover HIV Prep, so he went to Green Cross Pharmacy online and could order a 90-day supply for about $70.

The shipping charge is $1000!

[Guest]

8 hours ago, Lucky said:

A friend was told that Medicare does not cover HIV Prep, so he went to Green Cross Pharmacy online and could order a 90-day supply for about $70.

The shipping charge is $1000!

Regular Medicare doesn't cover medications. For medication coverage, one needs to add Medicare Advantage or Part D coverage. 

[chitownguy]

Medicare will soon begin to pay for PREP.  CMS recently issued a draft NCD-National Coverage Determination on PREP.  It is proposing to pay for PREP both oral and injectable without any out of pocket cost, including the related HIV testing.

https://www.hiv.gov/blog/cms-proposes-medicare-coverage-for-prep-invites-public-comment-by-august-11/

 

[Luv2play]

On 8/5/2023 at 5:50 PM, SirBillybob said:

These estimates can be calculated using the “probability of at least one” algorithm.

For 1/100 chance per event, 100 events produces a 63.4% likelihood of minimally one occurrence.

For the actual HIV risk estimate of 1/72 per event, 72 events produces a 63.8% likelihood of minimally one infection transmission; 100 events produces a 75.6% likelihood of infection transmission. 

Again, these figures relate to unprotected receptive anal intercourse with one or more ‘topping’ poz partners with detectable viral load. In Canada about one-quarter of people living with HIV have detectable viral load. 

Where did that statistic come fron about detectable viral load? Does it include newly discovered infections prior to treatment? It seems very high and what one might expect in the third world.

Edited August 24, 2023 by Luv2play

[SirBillybob]

18 hours ago, Luv2play said:

Where did that statistic come fron about detectable viral load? Does it include newly discovered infections prior to treatment? It seems very high and what one might expect in the third world.

There are a few sources with different figures, and quite a range of UDVL percentages, with variation among subpopulations but I provided a rough estimate 25% DVL, based on what I read, less representation by IVDUsers’ meds adherence (they inflate DVL rates) but accounting for infected yet undiagnosed. In contrast, MSM UDVL rates for diagnosed & on treatment are good. You have to sometimes just pick a rough estimate for a specific context. In this case the estimate of MSM HIV prevalence (UDVL + DVL) is 20%.

I can revise according to a few scenarios. 

The 1.4% per-event DVL risk (based on exclusively detectable insertive partner) for random encounters status unknown would be reduced by the estimate of percentage of MSM infected and the rate of undetectable, so with these metrics 1.4/20 (where 20 is 1/5 times 1/4) = 07%. Even then, the 1.4% from the literature estimates has a 95% confidence interval spread that puts adjusted risk metrics within a lower bound and upper bound that might seem quite a difference when probability is calculated as 1 in thousands. Obviously, these variations impact on cumulative event transmission probability as well.

Edited August 25, 2023 by SirBillybob

[LookingAround]

I’m on Apretude (the shot).  Anyone else on it?

[+ BenjaminNicholas]

5 hours ago, LookingAround said:

I’m on Apretude (the shot).  Anyone else on it?

Yep 👍

[Guest]

On 8/7/2023 at 7:33 PM, Luv2play said:

Most people over the course of two years will suffer from one or more of those side effects in any event. Headaches? Diarrhea? Fatigue? 

So how do they know it is caused by their taking PreP? In those stats, is the condition chronic if on PreP?

In my case it was pretty easy to tell. I took PrEP and got terrible diarrhea that was mostly water. I stopped taking it and the diarrhea went away. I tried again and it came back.

Condoms only from here on out fellas.

[spidir]

I'm on Doxy PEP after learning from my doctor that it significantly reduces the risk of chlamydia, gonorrhea, and syphilis. SFAF explains that it reduces bacterial STIs by 66% at About Doxy PEP for prevention of STIs.

[Your Man in Arlington]

On 10/21/2023 at 11:11 AM, spidir said:

I'm on Doxy PEP after learning from my doctor that it significantly reduces the risk of chlamydia, gonorrhea, and syphilis. SFAF explains that it reduces bacterial STIs by 66% at About Doxy PEP for prevention of STIs.

My doctor gave me a Doxy PEP prescription, and disclosed that he uses it as well. He did mention that if you're having frequent exposure periods (eg. 7 days a week), he doesn't recommend taking an antibiotic daily. My exposures are far enough in between that it I feel the added protection is worth it. In fact, due to my current schedule, I've only used on once so far and didn't experience any of the negative digestive side effects that he warned me of.