nos-trum. pronunciation: \nos'-trum\. noun. Etymology: Latin, neuter of noster our, ours.
1. a medicine of secret composition recommended by its preparer but usually without scientific proof of its effectiveness.
2. a usually questionable remedy or scheme.
See here for more discussion.

Sunday, July 11, 2010

Study: Increase In STD's Among Men Who Use Viagra

My first thought was...duh.  But looking at the details, I found that this is a much more interesting piece of research.

It's interesting because the simplest view of what's going on here... isn't correct.  See the USA Today Blog (July 11).

Guys take Viagra, they start taking advantage of the result, and the risk of exposure goes up, right?  It's like the old saying:  why does the dog lick himself?  Because he can.

(begin tortuous logical research analysis - bear with me)

But the study (Annals of Internal Medicine, June 9) was done in such a way that it appears the drug didn't lead to the risky behavior...rather, the behavior led to the drug, maybe.

The key to reversing the alleged cause and effect relationship--from Viagra -> increased behavior that risks STD's, to men with increased risk of STD -> seeking out Viagra--was to design the study such that you assess the risky behavior BEFORE they started taking the drug, and then compare that to the risk-taking AFTER the drug.

It turns out that those older men with ED who sought Viagra had higher rates of STD's in the year before taking Viagra.  In the year after taking Viagra, they were still at increased risk over men who didn't use Viagra.

The data the researchers were using for the study came from billing records that show diagnosis.  They matched up the paperwork on Viagra prescription, and treatment for STD.  There was no survey of the men involved, so there was no way to know whether taking Viagra increased sexually activity.  But you would expect so...else, why take it?

So, first interesting result.  This finding, only suggestive at this point, that older men with ED sought out Viagra not because their ED had made them sexually inactive...they weren't inactive (clearly...they had higher STD rates before taking the Viagra).  Possibly they sought Viagra for...well...the dispassionate way to put it is "to enhance the sexual experience."

[Note:  no data supported whether these men were more likely to be gay or not.  It wasn't relevant to the study.  It's important not to over-read what the data says.]

Second interesting result (and not adequately addressed).  STD rates fell in the year while taking Viagra from what they were in the year previous to taking the drug.  Is this just an ongoing falling STD rate, because the drop in STD rates occurred in the Viagra users AND the non-users.  Or was the apparent falling STD rate one that disappeared once the population was adjusted by various factors.   The authors believe the latter.  I can't tell.

For the research minded (Onion Peelers) (the boring data):
Users of ED drugs had higher rates of STDs than nonusers the year before initiating ED drug therapy (214 vs. 106 annually per 100 000 persons; P = 0.003) and the year after (105 vs. 65; P = 0.004). After adjustment for age and other comorbid conditions, users of ED drugs had an odds ratio (OR) for an STD of 2.80 (95% CI, 2.10 to 3.75) in the year before initiating drug therapy; the OR was 2.65 (CI, 1.84 to 3.81) in the year after.

(resume normal English)

One thing is clear.  Older men shouldn't assume they are less likely to get STD's.

Doc D

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