A review in the current issue of The Lancet Infectious Diseases has caused quite a hubbub and generated much media coverage, including this Seattle Times article.  The review states that the evidence that the flu vaccine saves lives in older people is quite flimsy and that the assumed mortality benefit of the flu vaccine in older people is vastly exaggerated.  One reason for this claim is that the original randomized studies that showed that the flu vaccine was effective in preventing the flu and effective in preventing deaths caused by flu had very few patients older than 70.  Though this age group (and young children) are at highest risk of complications from the flu, they also have immune systems that are least likely to respond strongly to a vaccine, casting doubt on the assumed mortality benefit that the flu vaccine provides.

The overwhelming reaction to this review seems to have been “OK.  So what?”  Even if the flu shot doesn’t save lives there are many other benefits, especially in older people, that make the vaccine a very good idea.  A prevented hospitalization, a prevented emergency room visit, or even a prevented miserable week in bed is well worth the brief jab and arm soreness that most people experience with the flu shot.

With the flu season approaching, the CDC recently made a statement encouraging the use of the flu vaccine.  The CDC page about the flu season, and flu prevention and treatment is here.  The CDC recommends that “in general, anyone who wants to reduce their chances of getting the flu can get vaccinated” but specifically recommends the flu vaccine for the following groups:

People at high risk for complications from the flu, including:

Children aged 6 months until their 5th birthday,
Pregnant women,
People 50 years of age and older,
People of any age with certain chronic medical conditions, and
People who live in nursing homes and other long term care facilities.

People who live with or care for those at high risk for complications from flu, including:

Household contacts of persons at high risk for complications from the flu (see above),
Household contacts and out of home caregivers of children less than 6 months of age (these children are too young to be vaccinated), and
Healthcare workers.

We just received our first supply of the vaccine last week.  If you have any questions about the vaccine, please let me know.

This week’s Annals of Internal Medicine has a very well designed study that examined the effect of exercise on patients with diabetes.  Previously sedentary diabetics were randomized to four groups:  one group was enrolled in an aerobic exercise program, a second group was enrolled in a resistance training program, a third group was enrolled in a program with both aerobic exercise and resistance training, and the last group (the control group) was encouraged to return to a sedentary lifestyle.  The patients were all followed to see the effect of these interventions on their diabetic control.

Not surprisingly, the aerobic exercise group and the resistance training group had a bigger decline in their blood sugar (meaning they had better control of their diabetes) than the sedentary control group.  The group that did both aerobic and resistance training had an even bigger decline than the groups that did either one alone.

By the way, the appendix of the article has a detailed description of both the aerobic and the resistance exercise programs, which may be handy if you’re planning an exercise program for yourself.

Even though the results are exactly what we would expect, I think the study is still very valuable.  A study that confirms our suspicions and puts them on a solid foundation of evidence is as helpful as a study that surprises us and forces us to reverse our opinions.  Doctors have always assumed that exercise helped diabetic control; now we know.

Tangential Miscellany:

Many of you have emailed me medical myths, popular but false beliefs about health and illness.  Thank you.  I’m still collecting them, so keep them coming, please.

My regular readers (both of them) have noticed that I spend almost as much time writing about new studies you should ignore as about new studies you should pay attention to.  That’s because the media is driven by hype, not by sober science, and there’s no incentive for an editor to get rid of a story just because the study is misleading or meaningless.  (I’m not complaining.  That’s a consequence of having a free press, and it’s much better than the alternative.)  So it’s up to us, the consumers of news, to figure out how to separate fact from fluff.

The upcoming LA Times health section on Monday has an important article that helps us with that task and explains why there are so many misleading studies out there.  You may have noticed in my previous posts that what separates reliable from unreliable studies is whether the study was observational (also called epidemiologic) or randomized.  Don’t get intimidated by the jargon; the difference is simple.  Pretend I want to test whether drinking four cups of coffee per day increases the risk of heart attacks.  An observational study would consist of me getting lots of people, inquiring about their coffee intake (or actually having assistants observe them and measuring their coffee intake) and then following them to see how many heart attacks they have.  A randomized study would involve enrolling lots of volunteers and randomly splitting them into two groups.  One group would be forced to drink four cups of coffee daily, and the second would not be allowed to drink coffee.  These groups would then be followed to see how many heart attacks happen in each group.

The Times article does a great job of detailing the reasons that observational studies are unreliable.  Even if coffee has no effect on heart attacks, my imaginary observational study above may show an effect simply because some other factor (sleep deprivation? smoking?) causes people both to drink more coffee and have more heart attacks.  The only way to know for sure is to do a randomized trial.  Observational studies have caused enormous confusion and much harm to patients.  The article relates how physicians were fooled for a generation into believing the health benefits of estrogen replacement on the basis of observational studies.  Randomized trials shocked us by proving the opposite.  Epidemiology has fooled us again and again, about estrogen, vitamins, the effects of diet on cancer, and many other subjects.  Hopefully the Times will help us all ignore such studies in the future.

Tangential Miscellany:

Did you know that anyone certified by the American Board of Internal Medicine after 1990 has to retake an examination and complete other requirements every ten years to maintain certification?  It’s true, and in a field that changes as quickly as internal medicine, I think it’s a very good idea.  If you’ll excuse a moment of bragging, I took the examination a few months ago and I’m happy to announce that I’m certified for another ten years.  You can check if an internist is board certified here.

Food additives are ubiquitous in packaged foods, and they have been blamed for many health problems despite the lack of evidence one way or another.  It’s easy to imagine patient groups or physicians noticing that their particular disease of interest is on the rise, whether asthma or breast cancer, and desperately searching for a cause.  Food additives entered the market in the second half of the twentieth century, so they provide a prime suspect for diseases that have worsened during that time.  Still, additives have passed the safety standards of the relevant government agencies, and no well-designed study has definitively linked them to any health hazard.  Until now.

This week’s issue of The Lancet publishes a study of the effects of food additives on hyperactivity in children.  The study attracted much attention from the media, including this article in Time.

The study randomized children to three groups.  Each group drank one of three fruit drinks daily.  One group drank a drink containing the amount of food coloring and sodium benzoate (a preservative) that is typical in a British child’s diet.  The second group drank a drink with lower amounts of coloring and sodium benzoate.  The third group drank a drink without any additives.  The drinks looked and tasted the same.  The kids’ behavior was rated by parents and teachers using standardized behavior questionnaires, and importantly the parents and teachers didn’t know which group the kids were in.

The kids that had the drinks with the additives were significantly more hyperactive.  Though the effects weren’t great enough to diagnose ADHD, the author speculates that the effects could diminish learning during school time.

I’ve always been very skeptical about the health concerns surrounding food additives, thinking that it was another manifestation of the misconception that natural substances are safer than artificial substances.  But there’s nothing like evidence to overcome my skepticism.

Tangential Miscellany:

I’m collecting medical myths, and I need your help.  Please email me health-related beliefs that lots of people believe but that are false.  Thank you.