On Risk and STDs

[mattbell]

I've recently been frustrated that people either tend to dramatically overestimate or underestimate risks of particular activities.  Neither one is good... people can end up paralyzed with fear or regretting their recklessness.  The frustration around unknown risk came up recently in  discussions of sexually transmitted diseases.  There are a lot of scary stories of bad things that can happen to you, and ... well... they can happen to you.  But if your response to these stories is to just sit around and remain abstinent until marriage like the Bush administration advises, well, you're missing the point and you're missing the fun. 

I decided to fix that.  After a few hours of research online, I now have as good a sense as I can about the risks of various STDs.  There are nice ways of quantifying risk.  For example, you can think of the risk of a particular activity or lifestyle in terms of the number of days it shortens your life on average.  For example, every time you skydive, you run about a 1 in 70,000 risk of dying.  If you're in your twenties, each skydive will cost you on average about six hours of your life.  I have a coworker who has done about 4000 skydives.  His lifetime of skydiving has carried a three year risk that he's fortunately beaten the odds on, but for him, it's worth it.

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Here's how this kind of thinking works:

There are some people who are very worried about catching HSV1 (oral herpes, aka cold sores) because it can lead to the fatal disease herpes encephalitis.  Crunching the numbers, catching HSV1 costs you about 4 days (or, if you prefer, 16 skydives :-).  Not too bad.  Which is good, considering 90% of people have HSV1 by age 50. 

Don't want to get Hepatitis B?  Get immunized.  It will add 9 days to your life.   

The big one, though, is HIV.  Because HIV is so deadly, there has been a lot of research on how dangerous the transmission is. 

Just one act of unprotected vaginal sex (receiving) from an HIV+ partner costs you 73 days (or 292 skydives).  If your regular partner catches HIV, they will very quickly suck the life out of you.   Use a condom, and it goes down to 1.5 days per act.  Unprotected fellatio with an HIV+ man costs the woman 5.8 days per act. 

Now there's a great reason to make sure your sex partner(s) are trustworthy and tested regularly. 

Then there's HPV.  What's frustrating about HPV is that the actual risks in transmission are not clear, and there's no way to test guys for it.  While the chance of HPV-induced cervical cancer killing you is low if you get regular pap tests, it can still lead to unpleasant surgery.  What's actually more dangerous is oral cancer caused by HPV.  HPV-induced oral cancer is currently shortening the average American's life by 22 days.  There's currently no oral pap test, and virtually no education on it.  This is one reason why I'm so excited about getting the HPV vaccine approved for guys -- from what I can tell of the pathology, there's no reason it wouldn't work to prevent oral cancers as well as it works to prevent cervical cancer.

This reasoning can be applied to other kinds of risks too. 

A lifetime of driving a car shortens your life by 91 days due to the chance of dying in a car accident.   However, all you have to do is wear your seatbelt, and you get 57 of those days back.  Sweet.  I'm looking to buy a new car.  I can get side impact airbags for an extra few hundred dollars.  It turns out that a lifetime of side impact airbags saves me 5.3 days.  Not bad. 

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Now, one important thing to remember is that all risks are based on averages.  If you're really choosy with your partners, the Hep B vaccine may only save you a few hours.  If you frequent gay bathhouses, it will likely save you hundreds of days. 

Also remember that the risks listed here are risks of death... there is also quality of life to consider as well. 

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I'm now feeling a lot better about STD risks.  It's a lot better than living in the dark.

Comments

[inferno0069.livejournal.com]

I have a coworker who has done about 4000 skydives. It's taken about three years off his life, but for him, it's worth it.

Not quite. The 4000 skydives he's completed safely have taken no time off his life. The next 4000 he may be planning, while their outcome is still undetermined, will take an expected three years off his life, unless his chances have been modified by his experience.

[crasch.livejournal.com]

Fascinating. What sources would you recommend for the statistical data? Texts you would recommend for learning to make such calculations?

[lynthia.livejournal.com]

Your brain is clearly still a fascinating place to be. :)

[yami-mcmoots.livejournal.com]

The HIV prevalence rate in the United States is only 0.6%, which means that unprotected fellatio on a randomly-chosen American man will take only 50 minutes off your life. With a randomly-chosen Swazi man it would be 2.3 days.

[chellmer.livejournal.com]

I have a few friends with HPV, and while it's not a big deal for most, two of them have had to have more aggresive treatments to cut the pre-cancerous cells out of the cervix. This can build up scar tissue and cause problems with getting pregnant. Oh, and it fucking hurts.

But like you say, you can't be afraid of everything.

[neoteny.livejournal.com]

So how would you evaluate non-life-threatening aspects for chronic conditions such as HSV-2, or being a carrier for HPV? Those things won't likely shorten your lifespan, but will definitely impact your quality of life.

[radiantsun.livejournal.com]

This is great, would you mind posting it as a comment here: http://www.sophisticatedrelationships.com/blog/?p=61 as it has to do with risk assessment and I think your math of this is fabulous!

[easwaran.livejournal.com]

Where did the transmission factor come from for unprotected oral sex on an HIV positive man? I was under the impression that there are only a few cases where that's the expected source.

Depending on the coding involved, you might make some sort of form using actual actuarial mortality tables, and the actual 1, 5, and 10 year survival rates for various causes.

And what's up with the oral cancer stuff? I hadn't realized oral cancer was even very common at all, but your numbers suggest that somewhere between 1 in 400 and 1 in 40 Americans get oral cancer due to HPV, which seems remarkably specific.

Also, that other factor of the percentage of the population with various diseases would be a nice coefficient to be able to add also (especially if the numbers are available by gender, orientation, age, and metro area or something).

[mary-wroth.livejournal.com]

You sort of address this at the end, but I guess I am still hung up on the averages issue versus what reality actually looks like for the individual.

The main issue (for me) continues to be that when attempting to quantify the risks associated with STD transmission, it varies SO MUCH from population to population. Sort of like the Swaziland comment above. The risk calculations seem like they need to be tweaked on a case by case basis in order to make any sense or to be reliable guideposts for adjusting behavior.

To me - it seems more effective to identify the behaviors that reduce risk generally. Rather than trying to figure out the average risk in X situation, especially when the risk assessment of the situation might be really off or really accurate.

[serolynne.livejournal.com]

I know we discussed this in private e-mail.. but I just wanted to add to your thread just how important the Quality of Life impact STDs can have to some people, and that it's not all about how many days it may take off your life.

Most folks I know who are concerned about HSV really don't take into account the unlikely fatal impacts.. but rather the annoyance/pain of re-occurring sores, the stigma of an STD, having to disclose to future potential partners, possible insurance coverage denial, taking regular medication to reduce re-occurance, etc. HSV isn't likely to kill you... but it can be a damned pain in the arse (or vagina, or mouth) for life.

Same with HPV. Of the 6.2 million new infections each year, only 4000 women will die of HPV-caused cervical cancer. Pretty good odds if you ask me. But what if the much more likely cost of HPV to you as a man was having a piece (or all) of your penis removed - would you still consider the impacts of HPV to just be 'unpleasant'? That's about what women face with it, and quite often. As a woman with HPV, I have lost my uterus, my cervix, my insurability as an individual (which limits my professional options) and not to mention the 5 years of stress of dealing with it which impacted my mobility, my relationship and sexual options, etc. And if I happened to be a woman who wanted to bear children (which I'm not).. it would be far more than just an 'unpleasant' consequence for the fun of having had 7 partnerships in a lifetime that included sexual intercourse.



Oh.. and another fallacy with looking at the risks in this way is that if you have a fatal car crash - you don't just loose 57 days of your life as your numbers are trying to downplay the consequences of. You loose the REST OF YOUR LIFE. And unless you happen to be 57 days shy of your natural life span... And what about if that car crash was *nearly* fatal and left you in a severely incapacitated stated for the rest of your 40+ year remaining life?


But really.. life should come with a warning label. 'Caution.. living is dangerous to your health.' Heck, I do jump out of airplanes, have sex, snowboard, etc.

[spoonless.livejournal.com]

every time you skydive, you run about a 1 in 70,000 risk of dying.

There are a number of reasons why this statistic is misleading.

First, there are so few skydiving deaths per year that it's not a good sample size. In 2007, for instance, there were only 18 skydiving deaths in the US (out of about 2.1 million successful skydives) whereas some years it is as high as 40... it all depends on the year. But the more important things is that skydiving fatalities are almost never due to chance... nearly all of them result from people who are trying to do stupid tricks, like swooping across the ground while barely touching it, and running into a building. It's extremely rare that a beginner skydiver dies, because they are fitted with extra safe equipment that has lots of extra redundancy checks and watched over like a hawk while they go. Only when skydivers have been jumping for years and years do the start to get careless... "trash packing" their chutes between plane loads, swooping, having "low pull" competitions with each other, and BASE jumping. All of these are much more dangerous than just going on a regular skydive... and that's mostly where the 20-some odd death per year come from. So for someone to see "1 in 70,000" (or even "1 in a 100,000") and to think that's actually the risk they're taking if they make one jump is ridiculous. I would estimate it's more like less than 1 in a million.

One statistic often cited by skydivers is that you have more of a chance getting killed in a car wreck than while skydiving, but this statement is somewhat misleading and needs to be phrased very carefully to be accurate. (I've heard some skydivers incorrectly say that jumping once is more safe than getting in your car to drive home after jumping, which is not true.) The more accurate statement is that jumping about 17 times per year is as equally risky as driving 10,000 miles per year in a car. So if you drive at least 10,000 miles per year and skydive less than 17 times per year, you have a greater chance of being killed in a car wreck than on a skydive:

http://travel.howstuffworks.com/skydiving8.htm

However, this is again based on pure statistics, and ignoring the issue of control/safety. Wreckless skydivers have a much greater chance of dying, just as wreckless drivers do. However, in the driving case, you have a lot higher chance of being killed by some *other* wreckless driver, which means that you have less control over your own risk while driving.