Friday, August 10, 2007

Medical Studies: Examine the Sample, Ignore the Media

Most studies use college students for the sample. For example, my biggest pet peeve study is the use of the Hep B vaccine in newborns. The vaccine study used not only on adults as test subjects, it used only on men. One could argue that we now have heaps of data since babies have been vaccinated for years, but that's just the point. The children were experiments. The vaccine required, for political reasons. On the outside chance the child turns out to be gay or an IV drug user, he or she is ostensibly protected from Hep B. There's all sorts of controversy about mandatory HPV vaccination. I'm still amazed that people willingly vaccinate their child against a disease, Hep B, that is easily preventable and entirely lifestyle dependent. Don't believe me? Here's the risk pool for Hep B:

What groups of adults are at increased risk of HBV infection?

  • Healthcare workers and public safety workers with reasonably anticipated risk for exposure to blood or blood-contaminated body fluids
  • Men who have sex with men
  • Sexually active people who are not in long-term, mutually monogamous relationships
  • People seeking evaluation or treatment for a sexually transmitted disease
  • Current or recent injection drug users
  • Inmates of long-term correctional facilities
  • People with end-stage kidney disease, including predialysis, hemodialysis, peritoneal dialysis, and home dialysis patients
  • Staff and residents of institutions or group homes for the developmentally challenged
  • Household members and sex partners of people with chronic HBV infection
  • Susceptible (non-infected) people from United States populations known to previously or currently have high rates of childhood HBV infection, including Alaska Natives, Pacific Islanders, and immigrants or refugees from countries with intermediate or high rates of chronic HBV infection. To see a list of these countries, go to
  • International travelers to regions with high or intermediate rates of HBV infection. To see a list of these countries, go to
Is your baby at risk? I think not. In addition, recent research shows that by adolescence, only 60% of kids show immunity. So the kids need to be boosted in youth? Why not just make the vaccine voluntary and give it to all the little junkies and sexpots with their HPV vaccine when they turn twelve so they can enjoy blow jobs and heroin in the back of the bus and not worry about consequences? Except, oops, they might still have to worry about throat cancer. Just keep the number of blow job partners under five. You should be fine.

Nuance. Or, you could just wait to get married to have sex. Or you could forgo using IV drugs.

Because college student samples are such a small population segment, it's difficult to understand why anyone cites them with any confidence. The numbers guy focuses on this problem. You should read his whole article.

But psychologists may be getting what they pay for. College students aren't representative by age, wealth, income, educational level or geographic location. "What if you studied 7-year-old kids and made inferences about geriatrics?" asks Robert Peterson, a marketing professor at the University of Texas, Austin. "Everyone would say you can't do that. But you can use these college students."

"People have always been aware of this issue," Prof. Peterson says, but many have chosen to ignore it. A 1986 paper by David Sears, a UCLA psychology professor, documented the increased use of college students for research in the prior quarter century and explored the potential biases that might introduce. In the meantime, the use of college students has, if anything, risen, researchers say.

And while the studies may have limited value, and researchers know it, reporters will jump on interesting research and put it in easily digestible language that misinterprets the results. It can be worse than misleading. Reporters rarely have a medical background and often get it wrong. Hmmm....reminds me of some of the military reporting.

Proceed with caution.

1 comment:

Sharon said...

When confronted with this vaccine while my son was a newborn (before we went home from the hospital), the pediatrician that was trying to talk me into vaccinating my innocent child admitted that it was an unnecessary vaccine for him. She said the thought behind the "requirement" (which turned out to be a recommendation) was that kids won't get the vaccination when they are teens, which is actually the time when they MIGHT become at risk. I declined...thankfully I had that much of my wits about me within 24 hours of giving birth!