Lesson on Confounds: When comparing circumcised to intact, don't forget the foreskin

Confound (freedictionary.com):

1. To cause to become confused or perplexed.
2. To fail to distinguish; mix up: confound fiction and fact.
3. To make (something bad) worse: Do not confound the problem by losing your temper.
4. To cause to be ashamed; abash: an invention that confounded the skeptics.

The first time I heard the word "confound" was in a graduate class where the professor was teaching us to be critical of published papers. She was talking about how to look for "confounds" which would render the results of the studies or experiments in the papers to be caused by something other than what the authors listed in their conclusions.

What makes me think of confounds today is the sudden appearance of news articles saying "Scientists Disagree about Circumcision Sensation" quoting two recent studies that contradict each other on whether or not a circumcised penis has less sensation than an uncircumcised one. Since I have a healthy distrust of the news media (they are trained and paid to find sensational stories, not be critical thinkers), I decided to go straight to the sources.

First, the news clip:

Kimberley Payne of the Riverside Professional Centre in Ottawa, Canada, and her colleagues tested the sensitivity of 20 intact
and 20 circumcised men's penises as they watched erotic movie
clips, by touching the penises with filaments that press down
with predetermined amounts of pressure.... They found no
difference in penile sensation between circumcised and
uncircumcised men.
However, when Robert Van Howe of Michigan State University used a similar method to measure sensitivity at 19 points along the penises of 163 men, he found that the five most sensitive points were all in portions of the penis removed by circumcision,
especially those in folds exposed as the penis becomes erect....

Something should already be fishy: Howe used more subjects, and we know how many points along the penises he measured. The reporter tells us how Payne measured sensitivity, but was that 1 point? 3? 10?

Now for the first study:

Sensation and Sexual Arousal in Circumcised and
Uncircumcised Men.
Kimberley Payne , Lea Thaler , Tuuli Kukkonen , Serge Carrier
, Yitzchak Binik
Introduction. Research, theory, and popular belief all suggest
that penile sensation is greater in the uncircumcised as
compared with the circumcised man. However, research involving
direct measurement of penile sensation has been undertaken only
in sexually functional and dysfunctional groups, and as a
correlate of sexual behavior. There are no reports of penile
sensation in sexually aroused subjects, and it is not known
how arousal affects sensation. In principle, this should be
more closely related to actual sexual function. Aim. This
study therefore compared genital and nongenital sensation as a
function of sexual arousal in circumcised and uncircumcised
men. Methods. Twenty uncircumcised men and an equal number of
age-matched circumcised participants underwent genital and
nongenital sensory testing at baseline and in response to
erotic and control stimulus films. Touch and pain thresholds
were assessed on the penile shaft, the glans penis, and the
volar surface of the forearm. Sexual arousal was assessed
via thermal imaging of the penis.
Results. In response to the erotic stimulus, both groups
evidenced a significant increase in penile temperature, which
correlated highly with subjective reports of sexual arousal.
Uncircumcised men had significantly lower penile temperature
than circumcised men, and evidenced a larger increase in
penile temperature with sexual arousal. No differences in
genital sensitivity were found between the uncircumcised and
circumcised groups. Uncircumcised men were less sensitive to
touch on the forearm than circumcised men. A decrease in
overall touch sensitivity was observed in both groups with
exposure to the erotic film as compared with either baseline
or control stimulus film conditions. No significant effect
was found for pain sensitivity. Conclusion. These results
do not support the hypothesized penile sensory differences
associated with circumcision. However, group differences in
penile temperature and sexual response were found.

OK, so Payne measured two points on the penis and one on the forearm (?) at different stages of arousal, also measuring temperature on the penis. They measured sensitivity on the shaft and head, but hmmmm, isn't there another part of the penis? the foreskin? isn't that cut off with circumcision? why not measure that, Ms. Payne?

Now for the other study:

Fine-touch pressure thresholds in the adult penis.

Morris L Sorrells , James L Snyder , Mark D Reiss ,Christopher Eden , Marilyn F Milos , Norma Wilcox , Robert S Van Howe

OBJECTIVE To map the fine-touch pressure thresholds of the adult
penis in circumcised and uncircumcised men, and to compare the
two populations.
SUBJECTS AND METHODS Adult male volunteers with no history
of penile pathology or diabetes were evaluated with a
Semmes-Weinstein monofilament touch-test to map the
fine-touch pressure thresholds of the penis. circumcised
and uncircumcised men were compared using mixed models for
repeated data, controlling for age, type of underwear worn,
time since last ejaculation, ethnicity, country of birth,
and level of education.
RESULTS The glans of the uncircumcised men had significantly
lower mean (sem) pressure thresholds than that of the
circumcised men, at 0.161 (0.078) g (P = 0.040) when
controlled for age, location of measurement, type of underwear
worn, and ethnicity. There were significant differences in
pressure thresholds by location on the penis (P < 0.001).
The most sensitive location on the circumcised penis was the
circumcision scar on the ventral surface. Five locations on
the uncircumcised penis that are routinely removed at
circumcision had lower pressure thresholds than the ventral
scar of the circumcised penis. CONCLUSIONS The glans of the
circumcised penis is less sensitive to fine touch than the
glans of the uncircumcised penis. The transitional region
from the external to the internal prepuce is the most
sensitive region of the uncircumcised penis and more
sensitive than the most sensitive region of the circumcised
penis. Circumcision ablates the most sensitive parts of the
penis.

Ouch, the most sensitive parts are cut off in circumcision and the circumcision scar is the most sensitive part left over? That's not very nice. They measured many locations on the penis, seeming to use the same method as Ms. Payne. But first, they eliminated all volunteers with penis problems. And then they ask how old they are, when they last ejaculated, what kind of underwear they had, their country of birth, education level, ethinicity.. dang they really want to make sure that nothing can confound their results. And by the way, those P values are results of statistical tests to prove the data is statistically significant, i.e. it's not a result of random chance.

Although, I do see one confound - Howe doesn't tell us what state the penis is in. Was it soft, hard, both? Looks like both parties may need further research.

And that, folks, is the lesson in confounds. If you don't control for everything that might change your results, critical thinkers won't believe your assertions. Since Ms Payne's group didn't measure sensitivity on the portions of the penis that are removed in circumcision, can she really say that circumcised penises have the same sensitivity? The only thing I get from her study is that the shaft and head of the penis feel the same, but I'm still curious about the foreskin. Hell, she didn't even say whether she turned away volunteers that had penis problems, but she did have age matched volunteers.

When using research to guide serious decisions, like whether or not to cut off the end of your newborn son's penis, you might want to look for confounds before you form your final opinion.

Circumcision HIV news frenzy

There's been alot of press lately covering two studies in Africa that show circumcised men contracting HIV at a slower rate than uncircumcised men. Pushing aside all the debate over what this does or doesn't mean, I want to know why there's so little press attention given to contradicting studies. For example an even newer study has shown that African adolescents who are still virgins, but have been circumcised are much more likely to have HIV than uncircumcised ones because they were circumcised in unsanitary conditions with shared knives.

My only guess is that the typical American man who was circumcised at birth doesn't want to admit his circumcision is useless. He doesn't want to admit his parents made a mistake. He doesn't want to admit that an ancient ritual body mod from the Bible is nothing more than an ancient ritual leftover in modern society. He doesn't want to admit he's missing out on something special. A recent South Korean study surveyed a large number of men who were circumcised after sexual maturity, and the majority reported worse sex, but that news story was drowned out by all the "Circumcision = HIV Vaccine!" headlines.

Judging by my previous posts, I have no readers, but if you read this, please comment on why you think there's no balance in the press coverage, or whether you had even heard of the contradicting studies.

Circumcision craziness

Anyone who knows me well knows that I'm strongly opposed to circumcision, but I've found it difficult to change the opinions of proponents and convince relatives I was doing the right thing by leaving my son intact.

The reason I'm opposed is becaused although the risks are low, I suffered from a side effect until I was about 20 and could find the cause and remedy. So it's very emotional to me, but one of my good friends has told me that my old way of arguing about it was just wrong, even though people who think circumcision is good just look stupid to me, nobody likes being told they are stupid, so I was just making them angry and closing them off, rather than drawing them over to my point of view.

I only started convincing my mom after reading up on all the statistics and numbers and studies, so I could show her counterpoints and examples of why common reasons to circumcise aren't that good. Lately I've been getting into economics, reading up stuff on finance and mostly microeconomics just so I can understand the ebb and flow of money to and from me, trying to control it more. So let's put my new economic knowledge to use on the circumcision debate. I could do a raw statistical argument, but there are a million websites out there already that try to do that from both points of view.

I'm going to do a quick rough cost-benefit analysis of neonatal circumcision with the common reasons why people advocate it, and hopefully try to explain why the American Academy of Pediatrics' official stance on circumcision is: "Existing scientific evidence demonstrates potential medical benefits of newborn male circumcision; however, these data are not sufficient to recommend routine neonatal circumcision."


1. UTI's in the first year of life - a neighbor that had a son after us was frustrated that he got sent home without circumcision due to being too jaundiced to have it done yet. She was afraid that he would get a Urinary Tract Infection, no doubt referring to a study that said uncut baby boys are a whopping 10 times more likely to get one in the 1st year of life than cut boys. If you look at the numbers from that study, it was something on the order of 1 in 100 uncut boys versus 1 in 1000 cut boys. In other words, that giant 10 times more likely was 1% instead of 0.1%. The cure for a UTI is a round of antibiotics. If you don't have insurance, the circumcision would cost about $150 and the antibiotics about $40..... so getting your baby boy circumcised to avoid a UTI in the first year of life is the same as paying $150 now to reduce your chance of possibily paying $40 in the next year from 1 in 100 to 1 in 1000. Granted most people have insurance that would distort the money they see out of pocket, but some insurance plans, most notably Medicaid in 16 states have dropped coverage of neonatal circumcision, like the UK national health service did in the 1940's.

2. Phimosis/Balanitis - Phimosis is a condition where the foreskin cannot be retracted fully. Technically all babies are born with it, since the foreskin starts off fused to the head of the penis, and should fully separate by sexual maturity, but some grown men still can't, and their condition is called Phimosis. Balanitis is inflammation of the head of the penis, and when really bad with the foreskin retracted, the foreskin can't go back to its natural state, covering the head. Both have simple nonsurgical cures, but when a man has these problems repeatedly or severely, he might want to be circumcised. So in America, alot of parents circumcise to avoid these problems. Let's say there are 1 million boys born every year and they all get circumcised. At $150 each, that's $150 million, alot of money. Even if Phimosis/Balanitis affected 6% of them, and all of those affected chose circumcision, that will only be 60000 men times $150, resulting in $9 million. Again, you might say "but insurance paid for the circumcision" and I'll say "but you paid for the insurance". Ignoring the medical costs of the boys who suffered circumcision complications (I'll get to that next) that's $141 million extra the insurance companies would have to pay out, and recover somewhere: higher insurance premiums... and people wonder why our health care costs are going up faster than inflation. Again, this boils down to paying for surgery on an infant because he may need it as an adult... paying $150 now to avoid a 6% chance of paying for it later at a possibly higher price.

3. Penis Cancer - Hopefully, the sheer probability numbers will show how weak the penis cancer argument is, but I'll try to break it down with a cost benefit analysis. A study has shown that penis cancer occurs in about 1 in 100000 uncircumcised men over 80 years old. Is the life expectancy for men even 80 yet in USA? A quick check with google shows it to be 75, meaning most men are expected to die before they are old enough to even get penis cancer. Ignoring the actuaries, my mom wanted us to circumcise our son to avoid penis cancer. Let's say there's 1 million boys born this year and all get circumcised at $150 each to avoid penis cancer. And let's say 10% live to be old enough to get penis cancer, so 100000. With the above probability, only one of them would have gotten penis cancer had he been left uncut. So $150 million worth of circumcisions have to be performed to prevent one case of penis cancer, but I won't stop there, I'm going to add in some of the circumcision complications. The rate varies depending on who you ask, but the complications vary from mild - excess bleeding, infection - to severe - loss of penis, loss of life. Let's take the low end, 0.2%, or 1 in 500, and while the medical costs to fix the complications vary, let's say they average out to $100 per person. Then 2000 boys suffered complications at a cost of $200000 to save this 1 old man from penis cancer, all while when caught early, penis cancer can be cured by freezing the tumor like you would a wart, or just cutting off the penis, probably at most $500. So when someone is asking USA to circumcise all our newborn boys to prevent penis cancer, they're asking society to pay $150 million now, $200 thousand real soon, just to avoid paying $500 on one old man about 85 years from now.

So there you have it: neonatal circumcision is not cost effective. Some people may point out the recent HIV studies. I deliberately left them out, because that issue is much more complicated, since it all boils down to sexual behaviors of a bunch of horny boys. So I won't pretend to know how much money dumped into sex ed it would take to convince teen boys to have safe sex or no sex, which is worlds better at preventing HIV than circumcision.

However, I do want to wrap it up with what convinced my sister we were doing the right thing by not circumcising. She was saying one of her boyfriend's frat brothers was embarassed because he had to miss class to recover from circumcision. She was concerned our son would have to go through the same thing in college. I told her that first of all, a low percent of uncircumcised men actually need it as adults, the ones that weren't circumcised and didn't need it also didn't feel the need to tell her about it. I then asked her if she would cut out the tonsils, appendix, or gallbladder of a newborn because it might cause problems later. She said no. It's the same thing. Doctors used to cut out kids' tonsils at the drop of a hat, but now they wait till they really really need to be taken out. I hope foreskins go the same way, doctors waiting to cut them off till they really need to go, insurance making non medically necessary circumcisions an out of pocket cost. In fact, the first intact boys I saw as a kid were sons of a doctor. The American Academy of Pediatrics knew what they were saying when they didn't recomend routine neonatal circumcision. Another way to phrase their stance is: the benefits do not outweigh the costs.