In November I wrote about an important study in the Annals of Internal Medicine that demonstrated the effectiveness of an antibiotic for the symptoms of irritable bowel syndrome (IBS).  Dr. Mark Pimentel, the author of the study, is the director of the Cedars-Sinai Medical Center Gastrointestinal Motility Program.  Last year he published a book outlining his theories about the cause and treatment of IBS:  A New IBS Solution.  After reading my post about the Annals article, he kindly asked me to review his book.

The cause of IBS remains mysterious.  Dr. Pimentel makes the astute point that when the cause of a disease is unknown, it is very frequently initially presumed to be psychological.  A generation ago, stomach ulcers were thought to be due to emotional stress.  (They are not.  They are almost always due to a specific bacterium or to anti-inflammatory pain medicine.)  Heart attacks were thought to be more common in patients with the “type A” personality.  (They are not.)  The assumption that IBS has primarily psychological causes has stigmatized IBS patients, and has misdirected researchers away from potentially useful diagnostic tests and treatments.

Dr. Pimentel’s central theme is that bacterial overgrowth is a major cause of IBS.  Bacterial overgrowth is a condition that occurs when bacteria that normally live in the colon (large intestine) move into and colonize the small intestine which is normally free of bacteria.  Small intestine bacterial overgrowth can be diagnosed by testing for specific gasses in exhaled breath, and can be treated with antibiotics.  In language aimed for the general public, Dr. Pimentel summarizes the evidence supporting this theory, and details the protocol used at Cedars-Sinai to manage IBS.  The book is also peppered with patient testimonials which help put a human face on a medical problem that is frequently very miserable.

The ideas in A New IBS Solution are an important breakthrough in a very common disease for which treatments up until now have been only marginally effective.  I will certainly recommend the book to all of my patients with IBS.

I’ve written before about the popular antiaging trend in healthcare.  Another medication that has been widely touted as an antiaging remedy is growth hormone (GH).  It has been shown to be beneficial in certain diseases (especially GH deficiency) but has also been recommended by some to healthy older people to increase muscle mass, improve bone density, and “reverse aging”.

A systematic review of randomized studies of GH in healthy older adults in today’s issue of the Annals of Internal Medicine examines this issue.  The results have been widely reported in the general press, including this L.A. Times article, and this article in Forbes.

The study found no significant benefit from GH, but several serious side effects, including soft tissue fluid retention, carpal tunnel syndrome, joint pain, and, in men, breast tissue enlargement.

The authors of the study conclude:

“Use of GH as an antiaging therapy is widespread and has been advocated in the lay press and in scientific literature. Our analysis shows that this practice is not supported by a robust evidence base, offers little clinical benefit to the healthy elderly, and is associated with high rates of adverse events.”

This week there are three brief items of Tangential Miscellany:

There will not be a medical news post next week.  The posts will resume the week of January 29.

The Pedometer Project starts on February 1.  Folks are still signing up.  Send me an email if you’d like to join.

Finally, a year ago this week I posted my first weekly medical news post.  I’m very grateful for all the helpful feedback and encouragement about the posts that many of you have given me.  I’ll try to continue to keep you informed, motivated, and healthy in the next year.

I never write about children’s health, since I have no training in pediatrics and my patients are adults. Nevertheless, I thought this story deserves your attention, particularly since many of my patients have young children.

The Centers for Disease Control released a warning today in their Morbidity and Mortality Weekly Report about adverse events in infants taking cough and cold medications. If you have a child less than two years of age, I urge you to read the entire brief article.

The issue seems to be that infants occasionally receive inappropriately high doses of these medications, leading to about 1,500 emergency department visits in 2004 and 2005, and three identified deaths. The packaging does not have dosing recommendations for children < 2 years, since the FDA has never tested appropriate doses in this age group. The bottom line is that the CDC advises parents to check with the child’s physician before giving cough and cold medications to a child younger than two, and to follow those instructions meticulously.

The part of the caution that surprised me most was that the medical literature has not demonstrated that cough and cold medications reduce cold symptoms better than placebo in children aged < 2. Perhaps in this age group we’re better off using humidifiers, saline nasal drops, nasal suctioning, and some patience.

Tangential Miscellany:

The pedometers have arrived! Dozens of patients and their friends have joined the Pedometer Project, which will start on February 1. It’s not too late to sign up!

The media constantly bombards us with studies purporting to show new evidence about medicines we should avoid, or foods we should eat, or behaviors that either protect us or harm us. Many of these studies, because of their design, actually tell us absolutely nothing. Nevertheless, the media is not in the business of downplaying the news, so the studies are inevitably announced in the mainstream press with much fanfare and little scientific scrutiny.

So that leaves us, the consumers of the news stories, with the responsibility of figuring out whether or not a study deserves our attention. A great example was a study last week in the Journal of the American Medical Association that linked use of proton pump inhibitors (PPIs, antacids such as Prevacid, Prilosec, Aciphex and others) to the risk of hip fractures. The most important thing to understand about this research is that it was what scientists call an observational study, and not a randomized trial. That means that the researchers followed many people who were taking a PPI and many who weren’t. They then counted how frequently hip fractures occurred in the two groups. They did not assign subjects to either take a PPI or not. They simply observed. A randomized trial, in contrast, would have been one in which each patient is randomly assigned to take either a PPI or a placebo (preferably without the patient or his doctors knowing which he is taking), and then the patients are followed and the number of hip fractures are counted.

Observational studies have very frequently given us misleading conclusions. For a generation we believed that estrogen protected women from heart attacks and strokes until finally a randomized study showed us that the opposite was true. Observational studies also suggested that lowering homocysteine might prevent heart attacks, and that dietary fiber might decrease cancer risk. None of these conclusions withstood randomized trials. Why do these trials give us flawed information? Because individual people are different from each other in myriad ways that can never be fully accounted for by the designers of the study. A generation ago, the women who chose to take estrogen were clearly healthier than those who didn’t, but it wasn’t because of the estrogen. Similarly, the patients on PPIs may be frailer or sicker than those not on them. Only a randomized trial will tell us for sure.

I think observational studies are very useful to help scientists generate ideas for large randomized trials. But patients and doctors are better off ignoring them.

Tangential Miscellany:

The response to the Pedometer Project has been very encouraging. I expect to receive the pedometers in about two weeks, so it’s not too late to sign up or to persuade a loved one to do so. Email me if you want to join. (Click on the link if you didn’t read about the Pedometer Project last week.)