Fully consistent condom use only 87% effective against HIV?

[marko]

@mhendo

It seems to me that the church might have gotten their figures from this study:

Karen R. Davis and Susan C. Weller, “The Effectiveness of Condoms in Reducing Heterosexual Transmission of HIV,” Family Planning Perspectives, Vol. 31, No. 6 (Nov. - Dec., 1999), pp. 272-279.

Link to first page. You need a JSTOR account to get the whole article. Here’s the article abstract:I have the whole article, and about one-quarter of it is devoted to a discussion of the results. The discussion contains a whole bunch of caveats, and makes clear that the results of studies like this are subject to many factors that are difficult to control for.

For example, the authors note that, while it is relatively easy to find good figures for transmission rates among consistent condom users, finding “unconfounded” rates for nonusers is more difficult, due to a variety of problems including selection bias. They also note that, in many cases, it is difficult to control for HIV risk factors not related to sex and condom use, such as intravenous drug use, and it’s not always clear, for example, whether those who do not use condoms might also be at higher risk of attracting HIV due to these other factors.

They note, in their conclusion:Note that the 87% figure for this study does NOT mean that, if a couple where one person is HIV+ have sex using condoms, they have a 13% chance of infecting the other partner. It means that the rate of transmission is 87% less than for couples where one partner is infected and condoms are not used. As the figures quoted in the abstract show, the 87% figure is found by comparing the transmission rates per 100 person-years for no-condom and always-condom use.

The figures the Vatican is using seem to be borne out by the literature. It seems to me, though, that the biggest problem is what the Catholic Church concludes, based on those figures. While it’s clear from the study that condoms are not 100 percent effective, the authors make clear that much ineffectiveness comes from improper use, which can in turn be at least partially offset by proper education. Also, while condoms aren’t perfect, i think it’s highly irresponsible to argue against their use simply because of that fact.

Admittedly, complete abstinence would be more efficacious, and this presumably is what the church is striving for outside of monogamous marriages. But we’ve already seen here in America how ridiculously unrealistic abstinence education is. It’s easy for the church to stand on the pedestal and shout that everyone would be fine if they’d just stop having sex, but that ain’t gonna happen.

Thanks for your legwork on this, and thanks for a great and informative post!

[ianzin]

@Malacandra

The point is that someone who makes such statements ought not to be viewed as incapable of making the same kind of verifiable statements about mundane matters as you or I.

This is true, but whether such a person is ‘capable’ of making such statements is hardly a matter of debate or contention (clearly, they are capable).

The point, often relevant to debates such as this, is whether such a person chooses to invoke an empirical approach (= develop understanding based on good evidence and good reasoning) when it suits them and then abandon it when it does not. This is at least culpably inconsistent, and at worst may be regarded as mendacious. If they wrap themselves in the cosmetic acceptability of empirical science only when they find it expedient to do so, and at other times disregard empirical science or even argue against its findings, they abandon any claim to integrity or fair participation in the debate. It is analogous to the man who says, ‘I am law-abiding when it suits me’, and who is therefore not actually law-abiding at all.

It seems that when the RCC speaks about condom efficacy, it has grounds for doing so - and it is insulting to presume out of hand that it would not.

Quite agreed, any such presumption would be unfair. However, I think we are entitled to ask the RCC or its representatives whether they think decisions should be based on empirical evidence or not. If they say no, then why should they be referring to these recent evidential findings and statistics about the efficacy of condoms? If they say yes, then we may ask for the evidence supporting some of their other contentions that they say should be respected and taken seriously, including proclamations about how millions of people should lead their lives.

[Spoke]

@mr.jp

The claimed condom failure rate for preventing HIV transmission is in the same ballpark as the failure rate for preventing pregnancy, so it sounds right to me.

Or that may just mean that 13% of people lie to scientists about always using a condom.

[Really_Not_All_That_Bright]

@Harriet_the_Spry

3. The risk of HIV transmission without condoms as reported in this study is about 7 per 100 person years.
4. The risk of HIV transmission with always use of condoms as reported in this study is about 1 per 100 person years.

That’s an 87% decrease (give or take).

[brazil84]

@mr.jp

One thing that people are also often mistaken about, is the risk of getting HIV from normal unprotected intercourse, which is about 0.05-0.1% per intercourse with an infected partner.

I’m not an epidemologist, but it seems to me that you need to break this statistic down between (1) male to female transmission; and (2) female to male transmission.

[theR]

@brazil84

I’m not an epidemologist, but it seems to me that you need to break this statistic down between (1) male to female transmission; and (2) female to male transmission.

What about male to male and female to female? I’m guessing that the gender of the person doing the transmitting is what matters the most, i.e. it’s easier for a male to transmit HIV than for a female.

[brazil84]

@theR

What about male to male and female to female?

Lol. I guess I understood “normal unprotected intercourse” to mean traditional carnal knowledge between a man and woman (without the use of a condom).

I’m guessing that the gender of the person doing the transmitting is what matters the most, i.e. it’s easier for a male to transmit HIV than for a female.

I think you are probably right.

[Bryan_Ekers]

Meh. Cecil made the point some time ago - condom use might drop the risk by a factor of ten (or eight - close enough) but being selective about one’s partners drops it by a factor of a thousand or more.

That the Church is stubbornly dumb (or dumbly stubborn) on this issue comes as no real surprise.

[SteveG1]

@Sage_Rat

It’s effectiveness is 87%. 87 times out of 100, it will be effective. Look at the sentence in the 3rd post, “Generally, the condom’s effectiveness at preventing HIV transmission is estimated to be 87%, but it may be as low as 60% or as high as 96%.”

87 percent is a LOT better than the 0 percent of not using them. Even 60 percent is better than 0 percent.