Newsflash: I am an epidemiologist. One of the important dimensions of epidemiology is using indicators correctly. I stress to my students that it’s important to consider when to use a relative measure vs. an absolute measure.
For example, there were 6 cases of cholera in the USA in 1999 (MMWR, 1999). Every case of cholera makes public health officials very nervous, because it may signal a potential outbreak. But 6 cases constitute a prevalence rate that is vanishingly small.
In 1998, there were 5 new cases of cholera. The additional case in 1999 meant an increase of 20%! A 20% incidence increase in any disease sets off public health alarm bells. But, really, there were only 6 cases in total. No biggy.
The relative measure was a 20% increase. The absolute measure was a single new case. Depending on which statistic you look at, you get a whole different picture of the cholera burden of the USA.
Now, my public health colleagues are going to have a fit over what I’m going to talk about next…
A recent study concluded that 30% of women who date online have had sex on the first date with gentlemen they’ve met online. (Zod bless those fine, upstanding women). Moreover, the study found that 77% of these women had had unprotected sex in those encounters. Of course, public health officials are outraged. The STI specialist quoted in the linked articled said,
“When you have unprotected sex with people you are meeting online, you are playing russian roullette [sic] with your health. It’s not a matter of ‘if’ you’ll get a sexually transmitted disease, but rather ‘when’ and ‘how many’.”
Well, I’m here to report that, epidemiologically, this is a bit of hyperbole.
There is no question that STDs/STIs are bad. There is no question that globally, and among some sub-populations, they exist in epidemic proportions. There is no question that one should always err on the side of protection, and wear a condom to protect oneself from pregnancy, STIs and overall ooginess.
However, that is no reason to conflate the risks suggested by the actual numbers! Let’s break it down..
In Canada, chlamydia is overwhelmingly the most common STI. The most recent reliable stats we have are from 2004. In that year, there were a total of nearly 63,000 cases detected. Chlamydia is a reportable disease, which means that the government is notified of every detected case; almost none fall through the cracks. Undiagnosed cases are, of course, unknowable, but are often tracked down if the infected person spreads it to others. In other words, 63,000 is probably a fairly accurate estimate of the chlamydia burden of Canada. (Compare this to about 9000 cases of gonorrhea and maybe 1000 cases of syphilis… very roughly.)
The Canadian STI surveillance report states that STIs are on the rise. Public health officials are worried about this trend. I’ve heard some use the word “epidemic”. In terms of chlamydia, there was a 70% rise from 1997 to 2004, from 113.9 to 197.1 per 100,000 population. The current prevalence is164 cases per 100,000 population, or about 0.16% of the total population, assuming a conservatively estimated base population of 35 million.
A 70% rise is a staggering number that necessarily warrants concern. But the prevalence is still only 0.16%. That means that probabilistically, you’d have to have unprotected sex with 625 random people before you were guaranteed to be exposed to someone with chlamydia.
Now let’s break it down further. Let’s say you’re one of these single on-line women, aged 35, currently disease free. The age-specific chlamydia burden among Canadian men aged 25+ is 9374 cases. Using an adult male population of about 20 million, that gives us a prevalence estimate of 0.05%. Thus, one of these single women would then have to have unprotected sex with 2000 random men in order to guarantee being exposed to chlamydia.
So far I’ve been talking about the chances of being exposed to an STI. What about actually contracting one? Well, the transmission rate of chlamydia is between 30% and 40%. In other words, only 30-40% of sexual encounters with an infected person will result in the disease being transmitted. This means that our hypothetical woman, in a worst case scenario, would have to have unprotected sex with 5000 random Canadian men before being guaranteed to contract chlamydia. And, of course, the number is even more outrageous for the less common STIs.
Given these numbers, I think our STI specialist above was being a tad hyperbolic when he said such women were guaranteed to become infected. Don’t you agree? To him I say, “Get a freakin’ grip, buddy.”
The truth is, thousands of people around the country are having unprotected sex all the time, and nothing bad is going to happen to most of them. This is not a reason to advocate unprotected sex– not at all. Do not mistake what I am saying! I am not condoning unprotected sex. Even a 0.16% risk is too much to always take lightly, in my opinion, when you can reduce it to near zero by using very basic controls, like a condom.
Rather, it is never justifiable to exaggerate risk, even if the intentions are pure. I would rather a society that treats its adults like adults and presents the numerical risks reasonably and accurately, instead of one whose public health officials shout out unfounded absolutes, which quickly devolve into medical propaganda.
As I was writing this blog post, I was surprised to find others exploring the same topic. This press release, for example, laments Canadian clinicians’ poor understanding of the true risks associated with unprotected sex and STIs.
I fully expect a public health practitioner to write to me now and tell me what a horrible person am. Here it comes…
Due to the sensitive nature of this post, I thought it best to clarify some things, in response to what was brought up in the comments:
- It is entirely possible that women who have unprotected sex with men they meet online share common behavioural characteristics that put them in a higher risk group for reasons beyond their “promiscuity”. (I don’t like using such judgment-filled terms, but whatever.) In other words, it’s possible that they’re not sleeping with random Canadian men, but with men who have a higher probability than the average of having an STD; club-goers, for instance, or atypically “promiscuous” men; or single men in general, who have a higher chance of infection than do married men. These women’s risk is therefore possibly orders of magnitude higher than I’ve indicated. But the numbers I’ve presented are based on known data; arguments about a higher risk “promiscuous” population are speculative.
- I have identified chlamydia as the #1 STD/STI in Canada. This is true, according to the Canadian STI surveillance system. But HPV may have much higher incidence and prevalence.
- While, according to my analyses above, the risk of contracting an STD is small, the fact remains that there’s a very small –but non-zero– chance of contracting HIV, which can kill you. One can argue that a risk of death is never trivial.
- The issue boils down to this: knowing how low the actual risk is may end up promoting the risky behaviour. But I’d rather my public health system give me the facts and not rely on fuzzy data and shock tactics to scare me into safe behaviour.
Today is Science Day at Deonandia. We begin with a submission from Anju G, this one titled, “Abdominal fat greater health risk for Chinese and South Asians“. Here’s the deal: we all know that fat is bad, despite what the busybodies advocating for “average” looking models might tell you. Fat increases your risk of a host of ailments, many of them life threatening. We also know that all fat is not created equal. Abdominal fat is far far worse than, say, chin fat or hip fat. People with “pear shaped” bodies are better off than those with “apple shaped” bodies. The worst fat is that deposited between the abdominal mesenteries, these membranes that cobweb through your peritoneal cavity (i.e., torso). The harder your fat, the worse, because hard fat is denser fat and therefore more abundant and unyielding, putting all sorts of untoward pressure on your internal organs.
Now, according this study, the effects of this deep, mesenteric fat are ethnicity dependent. South Asians and East Asians (i.e., Indians and Chinese people, for the most part) suffer more deleterious effects from this deep mesenteric fat than do Caucasians. Why is this important? For two reasons: first, all of our scales of risk are calibrated to the Caucasian case, because most Western medicine has been done by Caucasian scientists on Caucasian subjects, with the reasonable assumption that all races are physiologically identical. Second, this is important for the very reason that it reminds us that, despite our deepest political desires, all races are not physiologically identical.
This should be inherently obvious on a first-pass assessment. Different races look different, have different distributions of blood types and different prevalences of ailments. These data are confounded by social, economic and geographic factors, but there’s no denying that some biology is raciallt differentiated. Our peripheral blood vessels’ response to cold, for example, falls along a racial gradient, with Inuit people unsurprisingly having the most efficient heat-retention control with respect to peripheral circulation, Caucasians having second best, and those people originating in more temperate climes having the poorest control.
I don’t think this realization it hurts the basic premise that all human beings are created equal, just as an acceptance that men and women are biologically different should affect our supposition that both genders have equal intellects, contributions and rights.
On an entirely different topic is the story of this guy, who donated sperm throughout much of his 20s, and is now the acknowledged father of scores of children, all of whom call him “Dad”. As a fellow who has been approached on numerous times to be a sperm donor for either single women or lesbian couples, this story has special resonance for me. In the past, I’d said no, partly because of the inherent sadness of knowing there would be children out there with my DNA whom I could never claim as actual, functional family. Now comes this superhuman sperm machine to turn this supposition on its ear. Hmmm, thinks me….
I’m watching a French cartoon right now, in which our French hero travels to Scotland. The weird part is hearing French actors speak French with feigned Scottish and English accents! Beeeezarre!
Okay, looky what I found this morning at the much proclaimed online home of Canadian “conservative” thought, the Western Standard Blogs:
“Canadian Natives are fat Neanderthals living of the WAPs (White Anglo Persons). White Anglos must start organizing to fight for our rights. We are the down-trodden now. Wake up. Between Quebec, the Indians, the Muslims and the Leftist haters, we are screwed. It’s time to fight back!” –Yanni
I know, it’s like someone is doing performance art in the guise of a stereotypical bigot; but I guess stereotypes come from somewhere, huh?
I have reproduced “Yanni”‘s drivel here, not to list yet another example of that disgusting site’s evolution into a home for troglodytes, but rather to point out a phenomenon that may be obvious to many, but that nonetheless needs saying: the reason the extreme Right and extreme Left will never get along is that they are essentially identical, and those who preach hatred always hate themselves most. “Yanni”‘s post screams victimhood, a label most often applied to the Left. And indeed the extreme Left is rightly condemned for its penchant for blaming “The Man” for every ill that befalls the seaon’s favoured minority. Where the extreme Left and Right diverge is in their disagreement on which group has endured the most/worst/loudest victimization.
For those of you living under rocks (or in Timmins, Ontario… same diff), the head of the World Bank, Paul Wolfowitz, is in hot water for serious ethics violations. Wolfowitz was one of the chief neocons of the Bush II reign, and an author of the retarded War of Global Domination… sorry, Global War on Terror.
EK Hornbeck has expressed surprise that no prominent anti-Conservatives in Canada have expressed more public disappointment in how this country’s government is one of the few (of three, I think) World Bank members to continue to support Wolfowitz. Harper’s refusal to demand the former Bushite’s resignation is seen as irrational toadyism to Bush himself. More on this here.
What does the army of droogs out in Deonandia-space think of all this?
The Unkindest Cut
I miss my foreskin, I really do. It was taken from me without my consent and at great personal distress (I imagine). As I approach middle age, I’m convinced that every square millimetre of erectile tissue is worth triple its weight in platinum, and odds are that I will desperately need those few flaccid milligrams in a few years.
I never realized I was missing anything –since this generation of Canadians is populated almost exclusively by the helmeted set– until one day in youth I caught a glimpse of the Greek neighbour’s toddler son naked and uncut, and I exclaimed aloud, “What’s wrong with his?!” My father then took me aside to explain the horrific mutilation they had forced upon me and my brothers.
Okay, the baby-arm-holding-an-apple look has more character and visual charm than the baby-elephant-trunk or the tube-snake-in-a-turtleneck. But visual appeal aside, why do we non-semites do this to our sons? The semites do it for religion. But for the rest of us, the common argument is hygiene. And it’s true: circumcised men who do not practise good penile hygiene are far more likely to transmit sexual diseases, including HIV, to their partners.
As a result of this statistic, medical professionals in many countries, especially those with high HIV rates, are seriously discussing mandating the circumcision of every male child as a public health measure. I have a serious problem with this.
I believe it is an individual and a family’s right to cut or not to cut, though I would argue against it if asked my opinion. But to require the de-collaring of a shlong is another matter entirely, one which every civil libertarian should be concerned about. The analogy of vaccination is oft brought up in support of this Draconian proposal. We require the medical alteration of bodies through immunization as a public health measure, after all, so why not circumcision?
Well, vaccination simulates a natural process. It’s “shooting practice” for your immune system for when it does come into contact with an evil pathogen. Vaccination augments and props up the body’s innate defence mechanisms, at least in principle and philosophy. Circumcision, however, is quite the opposite: it’s the removal of a natural part of the body, thereby constituting mutilation; and there is evidence that this actually harms rather than helps the child.
Specifically, there is some evidence that circumcision without anaesthetic (which is commonly done at a very young age) impels a lower pain threshold throughout life. Furthermore, the lack of a foreskin may cause something called “keratinization”, in which the glans (or head) of the penis gradually becomes desensitized over time; in short, circumcision reduces sexual pleasure in the long run. There is, of course, also the small but real danger of botched circumcisions, which are genuinely horrific and life-ruining events.
Other analogies include appendectomies and tonsillectomies. But is anyone really advocating for the mandatory removal of one’s appendix and tonsils at birth? Why not laser blast all hair follicles while we’re at it? Or install a colostomy bag right away, so we’ll never have to worry about colon cancer, hemorrhoids or deforestation due to toilet paper overuse?
Lastly, consider this: what if it were shown that female circumcision also conferred a significantly reduced rate of STD and HIV transmission? Would the medical world be in as much of a rush to advocate mandatory female circumcision, too? The two procedures are not similar, I agree; we generally consider the female variety to be barbaric because it eliminates sexual pleasure. But if it’s true that male circumcision also reduces sexual pleasure, how is this then more moral?
As a society, we are becoming increasingly trigger happy with the “banning” and “mandatory this and that” guns. Instead of mandating circumcision to reduce STD transmission, why not mandate penile hygiene?
Suddenly I’m thinking back to that scene in Europa Europa. You know the one.