Saturday, November 26, 2005

The normalisation of cosmetic surgery

Seems these days cosmetic surgery is a normal part of life. More worryingly it's referred to repeatedly without the risks being highlighted. The latest strange move is that the NHS is offering staff a 10% discount on cosmetic treatments.

Now - just to try something really dramatic - compare and contrast having plastic surgery and having unprotected sex...

Plastic Surgery has a 0.21% (one in 476) mortality rate. That's based on data from St George's hospital, you can see it here.

The mortality rate from unprotected sex is basically related to the risk of catching HIV, since other STDs are generally considered to be manageable or curable. Unlike plastic surgery you might get another 20 years or more of life with HIV, but lets treat it as instantly fatal. The risk of catching HIV from unprotected heterosexual sex in the UK? 0.0006% (one in 1.7 million). The numbers I've worked on are below, with links to justify all my working...

So you're three and a half thousand times more likely to die during plastic surgery than to die from having unprotected sex. And actually thats a pretty conservative estimate as you can see from all the allowances I've made.
Now of course I'm not encouraging unprotected sex, of course not. But I don't think the NHS would want to encourage their staff to engage in it, do you? Why is it that cosmetic surgery can be talked about freely without mentioning the risks, while much less dangerous activities carry innumerable warnings?
What we need to address is why so many women (and it is almost always women) feel that they need plastic surgery. What is society doing to continually reinforce critical focus on their appearances? And isn't it irresponsible to do so without talking about less dangerous ways to improve self image? Such as ignoring media messages about idealised feminine forms?

And here are the HIV infection risk calculations:

There are approximately 58,300 people who are HIV positive in the UK. Here's the link. That's out of an overall population of 60,400,000. Of course we have to take into account the way in which HIV affects the population. So lets assume that it only affects people in the age range 20-49, there are 48,800,000 of them. Data here. And lets assume that 40% of them are, for religious or personal reasons, entirely celebate or at least monogamous throughout their lifetimes with one partner. So we'll exclude them from our numbers. Now on the other hand I think its fair to assume that two-thirds of HIV-positive people know their status and are careful to insist on precautions to avoid infecting others. So we have 19,400 HIV positive people who are at risk of passing it on, from a sexually active population of 29,300,000. Now of course one incident of unprotected sex with an infected person does not guarantee transmission of HIV. In fact it's estimated that the likelihood of transmission from one incident is 0.0009, or 0.09%. Data here. I'm ignoring the skew towards gay communities and intravenous drug-users in HIV infection, which would reduce the risk for women and those not involved with intravenous drug-use communities. Anyway we end up with a risk of 0.00006% per incident of unprotected heterosexual sex in the UK. (One in 1.7 million).


darky said...

Hi from the antipodes.
The stats exercise was fun.
My first reaction to your 6 to the minus 6 odds (damn no full html) was - gee that looks much too easy to catch.
My treatment of the two probabilities gave 6 to the minus 7.

The way to make some meaningful hypotheses around this kind of population stuff is to get hold of a population boffin, squeeze some trends out of them and then run the stuff through a Bayesian analysis. Bayesian gives a lot more useful stuff where conventional bell-curve stats always assumes that everything is unknown - thus the probabilities for things where one has intuitive or at least a common-sense overview often sound more-or-less ridiculous.
The above is not to try to sound like I am a stats mavin, it's just that you write about it as though you like doing that kind of thing - as I do.

Whatever, I've always wondered why the bloody panic over HIV contagion in our sexually repressed protestant healthy immune-sufficient little lives.

Andy said...

Hi. I'm no stats expert but there's a glaring flaw in your analysis in that you assume, if one has unprotected sex with somebody, then the chance of it being with someone HIV positive is just the fraction of HIV positive people in the sexually active population. Of course there is a completely non-flat distribution of sexual proclivity amongst adults in the UK, and the most sexually active are the most likely to have HIV. I can't think of any reliable way of quantifying this effect but I would suggest it could increase the probability of your one-night-stand being HIV positive by orders of magnitude from your estimate.

Also the phrase "So you're three and a half thousand times more likely to die during plastic surgery than to die from having unprotected sex" is misleading because people who have plastic surgery, do so once or maybe a few times in their life. People who have unprotected sex with new partners are likely to do so far more times - it's a lifestyle. This makes a comparison of the risk per incident meaningless.

Cruella said...

Interesting. Couple of things - firstly darky, I don't think there's much point doing complicated statistical analysis on the numbers. There are far too many estimates and assumptions.

And both of you, yes I'm not claiming to be perfectly accurate, but since my numbers come out at a skew of 3,500 times, seems like even with different assumptions, it is likely that we'd still see plastic surgery the more dangerous activity.

andy - one point though, I've been surveying my friends on the subject, asking them how many times in their lives they're had an unprotected sex one night stand. Almost all of them have(!), but few have done so more than 5 or 6 times. I am inclined to agree that there may be a sexual "more at risk" group of people who have had, lets say, more than 100 incidents of unprotected sex. This group might comprise sex workers, those who visit them (from the friends I've surveyed so far only one has ever visited a prostitute, and only one, and only for oral sex), those who enjoy "dogging" (none of my surveyed friends have done this, though one hid in a bush once and watched other people doing it!) and those who due to drug addiction or others extreme personal circumstances might find themselves being co-erced into having repeated unsafe sex. Since I'm guessing my average reader is outside that group, and unlikely to be going home with anybody in that group - the risks would be even lower since we would expect infection rates outside the "more at risk" group to lower than just a population average.

Of course the "I asked my friends" arguement doesn't prove anything. People who have had plastic surgery are much more likely to have further surgery than new customers are to have surgery for the first time. In order to balance out the risk of one surgical proceedure, I'd have to have unprotected sex 3,500 times. That would be pretty tiring!

Ethan_24 said...

Cruella - I was born with three bums, i had a medical condition called asstriophacy. After reading your article I must confess that i feel quite guilty of having three bums, I think i may now longer go ahead with my operation. After all -what is normal? ... im happy with my extra friend. Thanks!

Cruella said...

Great news. You should consider yourself bottomly-gifted and celebrate your extra ass!

I do think that plastic syrgery is a slightly different issue when dealing with disfigurements. But drawing a balance between wanting to have a normal appearance and challenging what society sees and treats as normal is a positive step.

There is a fascinating article about Vicky Lucas, who has refused surgery for her cherubism here:

Ethan_24 said...

Thats great - im still not entirely sure if i should go ahead and cancel my operation? I think my girl friend would be dissapointed, I have to wear all the CK trunks she has bought me back to front to fit - i know shes excited to see them on the correct way round.

breast said...

plastic surgery is ok as long as people use it to improve themselves rather than changing themselves