Friday, August 30, 2013

BMI - an Imperfect Measure of Obesity-Related Health Risk

Finally, people are starting to recognize that the BMI (Body Mass Index) scale is an imperfect predictor of health risk as it relates to obesity.  Yes, in the very broadest sense it works for whole populations, but it seems to break down when it comes to being a good predictor of an individual’s risk for obesity-related diseases.

A recent analysis of the topic can be found in an article by two University of Pennsylvania researchers.  They argue convincingly that we need to know a lot more than just BMI to be able to predict a person’s future risk of diseases related to obesity and metabolism with any degree of accuracy.  The researchers point out that earlier research (by Flegal et al.) shows that being slightly obese is actually protective in some individuals.  Furthermore some individuals with normal BMIs are actually at high risk for obesity-related diseases because they are “metabolically unhealthy”.

You can’t pull up the article in Science magazine online without a username and password, so I’m passing the URL for the article on to you here.  The article can also be found in the Aug. 23 hardcopy issue of Science.

Sunday, August 25, 2013

Were the Flores People a Separate Species?

Ever since they were first discovered in 2004, the skeletal remains of a diminutive group of humans found on the island of Flores in Indonesia have been at the center of a controversy. Did the Flores people belong to a previously undiscovered species of the genus Homo, or were they simply modern humans (Homo sapiens) who suffered from some sort of growth disorder?

New evidence strongly supports the new-species hypothesis. In a paper published in PLOS One, researchers used CT scans to compare the brain shape of the one available skull of a Flores person to primitive species of Homo, to modern humans, and to modern humans with various growth disorders. They conclude that the Flores people are most closely related to the primitive human species known as Homo erectus. Furthermore, the evidence did not support the hypothesis that the Flores people were modern humans with a growth disorder, and so it seems appropriate to consider the Flores people a separate species of primitive Homo. Scientists have named the new species Homo floresiensis in honor of where they were discovered.

That’s where we stand today, at least. But the fact is that all this talk of a new species is based on just one skull and a partial skeleton, plus a bunch of bones of other individuals of the same group. It would be nice to have a few more skulls to really nail this thing down. Perhaps in time….

Wednesday, August 21, 2013

Diagnosing Concussions in Athletes Quickly and Inexpensively

Imagine that a high school football player takes a hard hit during a game. He seems a little shaken up, and he's a little little wobbly as he leaves the field, but five minutes later he swears he’s fine and wants to be put back in the game. But if he’s had a concussion, he’s not supposed to return to play. What tools does the coach or trainer have to try to determine whether he’s okay to play or not? After all, not all hard hits result in concussions; he’s probably just fine….

A common finding after a concussion is that the person’s physical reaction time decreases. But how can one measure a decreased reaction time quickly and accurately on the sideline? Researchers at The University of Michigan developed and validated a simple technique - here’s how it works. The athlete rests his forearm comfortably on a table with his opened hand extended just off the front edge of the table. A trainer or coach holds a measuring rod such as a yardstick by its upper end, positioning the lower end at the athlete’s hand level. When he lets go of the stick, the athlete grabs it. Where the athlete grabs the measuring rod (the number of inches that the rod falls before he grasps it) is an indirect measure of reaction time. If measurements of reaction time are made on every athlete before the season begins, slower reaction times can be determined easily and quickly any time a concussion is suspected.

Of course, the method only actually measures the distance the rod falls before the athlete grasps it, so it’s not a true measure of reaction time. But that doesn’t matter; if the rod falls more than usual before the athlete grasps it, his reaction time is slower and he should be evaluated by a medical professional before he is allowed to play again.

For those who are interested, the method is described in a publication in the Brit. J. of Sports Medicine.

Sunday, August 11, 2013

New Recommendations for Screening for Lung Cancer

The U.S. Preventive Services Task Force (USPSTF) has published a draft of potentially new recommendations for screening high-risk persons for lung cancer.  The USPSTF now recommends that smokers aged 55-80 who smoked at least one pack a day for 30 years should have a low-dose CT scan every year.   The draft recommendation is available for public comment until August 26, after which the recommendation is likely to be approved.

Screening normal healthy people for lung cancer (with traditional chest x-rays) is generally not done. In part, that’s because x-rays generally catch lung cancers too late for lifesaving treatment anyway.  In addition, x-rays sometimes produce false-positive results, leading to needless stress and unnecessary medical procedures.  On balance, then, the benefits of routine chest x-rays for detecting lung cancers just don’t outweigh the risks.  However, modern CT scans can pick up smaller tumors than traditional x-rays, leading to earlier and thus more effective treatment.  That tips the benefit/risk balance, at least for smokers at high risk of developing lung cancer.  The USPSTF estimates that screening high-risk smokers every year could save about 22,000 lives per year.

If the USPSTF’s draft recommendation is eventually approved, insurance companies will probably pay for annual CT scans for smokers who meet the screening criteria.  So will Medicare.

Tuesday, August 6, 2013

Could Stem Cells Feed a Hungry World?

Scientists have succeeded in producing edible meat from stem cells taken from a beef cow, according to CNN news. The first “stem cell burger” cost over $300,000 to produce. It didn’t get rave reviews in terms of taste, but that’s to be expected; it was pure meat, without any fat at all. But it wouldn’t be hard to add a little fat back in. Perhaps someday scientists will be able to produce the fat from stem cells as well.

Despite its cost and taste, this first edible meat from stem cells represents an important “proof of concept”; it’s possible to produce animal protein in laboratories, rather than on the range. And that might just save a hungry world population if (heaven forbid) a shortage of range land or water ever limited our ability to raise enough animals for food.

Saturday, August 3, 2013

Low HPV Vaccination Rate Among Adolescent Girls

A weekly CDC report indicates that fewer than 35% of adolescent girls aged 11-13 have been fully vaccinated with all three doses of the vaccine against the human papilloma virus (HPV).   The percentage did not increase at all between 2011 and 2012.   Officials have been pushing the HPV vaccine because it has been proven to be very effective in lowering a woman’s risk of developing cervical cancer later in life.

Officials are not sure why the percentage of girls who have been fully vaccinated remains so low.   Part of the problem, of course, is that full vaccination requires three visits, rather than just one.  Indeed, 53.8% of girls had had at least one vaccination by 2012, but then a lot of them failed to receive the other two.

The reason for the failure to receive the 2nd and 3rd doses of HPV vaccine clearly is not parental resistance to giving the vaccine to girls so young (before they are sexually active), because so many girls have already had the first dose.  Nor is it a lack of opportunity, since girls of that age do go to the doctor for other vaccinations.  Officials speculate that physicians are simply missing the opportunity to offer the vaccine.   Officials calculate that if girls had been offered the HPV vaccination during the girls’ regular doctor’s visits, the percentage of girls who had received more than one vaccination could have been as high as 92.6%.

And that means that the focus of the CDCs efforts may have to shift to physician education, rather than parental education.