Showing posts with label BMI. Show all posts
Showing posts with label BMI. Show all posts

Thursday, May 31, 2007

Study: Pediatricians Failing our Kids!

Earlier this week the Buffalo News carried Pediatricians slow to treat childhood obesity; an article critical of pediatricians - they were found in a survey to be "failing in large numbers to take Step 1 in the manual of fat prevention — calculating a child’s body mass index, or BMI." [emphasis mine]

Here readers are led to believe that Americas pediatricians are negligent in their basic duties of standard care for children - they're not calculating out BMI to "prevent" obesity in children.

Never mind the fact that the large majority are indeed weighing and measuring children at their routine well-child visits; ignore they have eyes to see and recognize a child who is too heavy; and heck, let's just forget they have experience, experience, experience, with years of taking care of kids to recognize the difference between an obese child and a normal child in their care.

Nope, let's just chastise them for exercising clinical judgement in their practice of medicine because they're not in lock-step with the additional recommendation to now calculate and chart BMI to "prevent obesity."

**sigh**

Some days I'm just tired of the misinformation and misleading of the public.

Calculating a BMI is data collection - nothing more; nothing less - and like any data collection, its usefullness is only as good as what one does with the data in hand.

Data such as a calculated BMI does not prevent disease (obesity); it is only a piece of a larger picture, and is a piece of data that is considered by many to be highly unreliable as a predictor of health.

Imagine for a moment you're a doctor, a pediatrician, and you've just weighed and measured this child:




















He's five, stands 3'10" tall and you've determined he weighs 54-pounds, thanks to the nurse who weighed and measured him then added those figures to his chart before you entered the exam room.

You give him the once over and note he's lean and healthy; his mother tells you he's very active, quite a little monkey outside climbing, running and jumping whenever he has a chance - and you note too that he is itching to get out of your office as quickly as possible, laughing gleefully as you continue along with your physical of him.

Do you calculate his BMI at this point in time?

No? No you say?

Why, you've missed this healthy and active kid is at the 95th percentile according to the BMI - in children, that's "overweight," the politically correct way of classifying a child who registers obese on the BMI chart.

In this example, this child is one of the roughly 15% in our nation classified as "overweight" for age.

So much for your clinical judgement - you failed to recognize the fat kid in need of intervention to improve their diet and activity levels before they develop other diseases correlated with obesity!

**sigh**

So what are we to make of the survey?

How about some context.

The researchers reviewed the charts of 400 children and found pediatricians calculated BMI in roughly 1 in 20 children; while 91% did actually weigh and measure height in kids.

Somehow the researchers failed to ask or look at those who were calculated to compare to those not calculated - perhaps these pediatricians fail not in their care, but rather fail to see the usefulness of calculating each and every child, especially those obviously a healthy weight.

Let's do math!

According to the IOM, it's estimated that roughly 15% of children this age are at or above the 85th percentile for BMI. A closer look defines an estimated 10% are at or above the 95th percentile for BMI.

Children who hit the 85th percentile for BMI are said to be "at risk for overweight" and those who reach the 95th or higher are said to be "overweight."

Stated another way, 85% of kids are well within normal weight, and some are underweight (as problematic potentially as obesity) with BMI calculated below the 85th percetile; another 5% may be "at risk" for becoming overweight/obese because they fall between the 85th and 94.9th percentile for BMI.

Simply put - 90% of children today are not obese; 85% are not obese or at risk for overweight.

But we don't hear or see that much in the media, do we?

The media and authorities, it seems, are working really hard to scare the beejeebers out of parents these days.

Yes, the prevalence of children who are calculated as having a BMI at or above the 85th percentile has indeed increased. Where in the 70's roughly 5% of children were at or above the 85th percentile, today roughly 15% are.

But we're communicating the increased prevalence in terms designed to make the increase an issue for every parent to not only worry about, but do everything in their power to change, when the fact is that 85% of children are normal weight (or underweight).

We're not just targeting adults with the message we have a problem in the United States - today every child is being targeted - with messages about diet, exercise, risks to future health, and even the potential of premature death; hearing, repeatedly, they'll die at an earlier age than their parents because kids today are too fat.

We really need to ask ourselves, must we target all children in our attempts to reduce obesity in some children, or are our resources and time better spent when they're directed and focused on the children who really do need some help?

While it may seem useful to chastise pediatricians, whom are quite competent in their daily practice of medicine, for not calculating every child's BMI - maybe a better question is why are they being asked to when 85% of the kids walking into their office each day are not too heavy?

Do we really think pediatrians are so daft they'd visually miss recognizing an obese child?

Do we really want to require a doctor to spend time calculating out the BMI for all children s/he sees and chart they actually did calculate it out too, when 85% of the patients are likely to be below the 85th percentile?

Add to this, a percentage of the children falling at or above the 85th percentile are not really overweight or obese - by the simple BMI they are, but as the above picture illustrates visually, the BMI is not always an accurate measure of true fatness that should cause concern.

How useful is it really, in the long-term, to have every parent in America wondering if their pediatrician is failing their child because they're not calculating BMI at the office visit?

Thursday, May 24, 2007

Impact of Community Based Diet Intervention, More than BMI

There's been a lot of fuss over the publication of the Shape Up Somerville: Eat Smart Play Hard.™, initiative results in the May issue of Obesity. (abstract)

As noted in the abstract, the objective "was to test the hypothesis that a community-based environmental change intervention could prevent weight gain in young children" as reflected in the change in BMI z-score.

In total, 1,178 children were enrolled - 385 in Somerville (the intervention group), and two control communities, one enrolling 561 children to be followed, the other 232 children to be followed. All the children were in grades 1 through 3 at the beginning of the study period, school year 2003-2004 (September to June).

The intervention was intensive, and expensive.

Overall, the researchers started with a $1.5-million dollar CDC grant. And, if that were not enough, the Tufts website notes the grant "received supplemental support from The US Potato Board, Dole Food Company, Blue Cross and Blue Shiled of MA. It is also supported through generaous donations by Whole Foods Market, WGBH, New Balance, Gaining Ground, Annie’s Homegrown, Stonyfield Farm, Organic Valley, White Wave, Earthbound Farms, Shaw’s Supermarkets, Cabot Creamery, Friendship Dairies, Newman’s Own, The Vermont Bread Company, and the Kashi Company."

The Wall Street Journal included some idea of this supplemental support in quantifiable terms...

"...the Tufts researchers helped the city win a grant from the Robert Wood Johnson Foundation for a bigger-ticket item, an extension of a bike path that will eventually go all the way to Boston. "

"...the City Council came up with its own ideas: reimbursements on gym membership for city employees and dozens of new bike racks for schools and streets."

"...Dr. Economos persuaded a Whole Foods store to donate about $35,000 in fresh produce."

"...a Department of Homeland Security grant is providing fitness equipment at fire stations and chefs to train the firefighters about nutrition and healthy meals."

"...a doctor sponsors the community fun run."

So, it's hard to add up all the additional monies and in-kind donations to know the true cost of the initative, but Somerville has secured an additional $1.5-million dollars to continue the efforts.

What exactly happened in Somerville that so much attention is focused on this small town?

Throughout the city of Somerville, the efforts to place the towns children on a diet and increase activity included:
  • School lunches, classroom snacks and fundraisers revamped

  • Teachers were trained to implement the new health curriculum, called The HEAT Club (Health Eating and Active Time)

  • School Staff Role Modeling implemented

  • After school program policies created for snacks

  • After School policies for physical activity developed

  • Increased time for recess, lunch, and physical education

  • Annual height and weight data collected with reports for parents

  • Monthly newsletter was sent to parents

  • Monthly community newsletter to community members

  • Parent education forums held for non-english speaking parents

  • Area restaurants developed "Shape Up Approved" menu items

  • Safe Routes to School maps were created

  • Crosswalks were re-painted in thermoplastic material

  • Bike racks installed at elementary schools

  • School nurses and area Pediatricians were educated about taking weight and height of children

I don't think they missed an opportunity to intervene, do you? No Child Left Behind - heck, this was an "in your face" intervention, with no one left behind.

Throughout Somerville, it was impossible to escape the Shape Up Somerville messages.

So you'd think the results would be impressive given the media's attention the last few weeks.

The researchers trumpted "A community-based environmental change intervention decreased BMI z-score in children at high risk for obesity. These results are significant given the obesigenic environmental backdrop against which the intervention occurred. This model demonstrates promise for communities throughout the country confronted with escalating childhood obesity rates."

Based on their results that found over eight months, "At baseline, 44% (n = 385), 36% (n = 561), and 43% (n = 232) of children were above the 85th percentile for BMI z-score in the intervention and the two control communities, respectively. In the intervention community, BMI z-score decreased by –0.1005 (p = 0.001, 95% confidence interval, –0.1151 to –0.0859) compared with children in the control communities after controlling for baseline covariates."

Simply put, the kids in the intervention group gained about 1-pound less than the kids in the two control towns who received no intervention.

They didn't lose weight, they just gained less, which is expected - growing children gain weight each year (or are supposed to).

Within the full-text we find a curious table designed to highlight the effect of this intervention, Estimated intervention effect over 8 months on a child at the 75th percentile BMI z-score, which seems contrary to the objective of reducing the incidence of overweight and obesity, which is defined as a BMI that places a child in the 85th percentile or higher.

Nonetheless, the researchers included it to show how the intervention would effect children at the 75th percentile - children, it should be noted, already within the definition of a "healthy weight" for age.

It seems to have escaped many that with or without intervention such a child would remain within "normal, healthy" weight, as evidenced in the table data included.

Case in point - highlighted in the table - a boy, at baseline 8-years old has a BMI of 17 and is in the 75th percentile. Eight months later, without intervention (it's hypothesized) he might grow about an inch-and-a-half and gain 5.07 pounds; with intervention, just 4.25-pounds (a difference of 0.82-pounds, or about 12-ounces).

Without intervention the child's BMI is now 17.4; with intervention it is now 17.17 - in both instances the BMI increased, right?

But in both instances the child in this scenario fell on the charts, going from the 75th percentile to the 73.9 percentile without any intervention and the 71.1 with intervention, and at a cost of $1.5-million to keep this hypothetical child well within "normal" when he would have remained there anyway?

I wondered, what happened to the kids who were overweight or obese to start - the 170 of 385 children in the intervention.

As I combed through the data, another curiosity - no data was provided to show the intervention was effective for this particular subset of children within the intervention group.

Why was that data not provided?

I would think that would be the icing on the cake for the researchers to highlight the benefit of such an intense intervention, wouldn't you?

So, I got to thinking, what changes, based on the data provided, might happen for a child within this group?

The researchers neatly summed up the hypothetical child within normal, so how about we create the same table for a child who was at the 95th percentile at baseline to see what might happen.

Johnny is 8-years old, he stands 4' 2.25" and weighs 72-pounds - BMI 20.1, 95th percentile.

In eight months, like the scenario presented by researchers, he now stands 4' 3.75" (growing 1.5") and without intervention is likely to weigh 77-pounds (gained five pounds); with intervention he'd weigh about 76-pounds (gained four pounds).

Without intervention he's fallen to the 93.8 percentile; with it he's fallen to the 93rd percentile.

Yes - with or without intervention this hypothetical child went from "overweight" to "at risk for overweight" - which begins to explain the absence of data on the subject of where the children were on the charts at the end of the study period.

I'm not trying to say we shouldn't try to help children engage in more activity or eat a healthier diet, but quite frankly, these results are not as impressive as we're being led to believe.

We have no data to look to in our understanding of how this type of aggressive community-based intervention impacted children already underweight or at the bottom of "normal, healthy" weight; we have no clue as to how this type of intervention impacted those children who were well within "normal, healthy" weight; and without the hard data we don't know that any of this helped those children at risk for or already overweight!

I'd like to see the data and also see someone investigate impacts in other areas of life, like reading and math scores. Sandy Szwarc, over at Junkfood Science, pointed out that "While the school year was absorbed in diet and exercise, (after the Shape Up program was completed in 2005) the average reading test scores among Somerville kids are 15.4% below state average, and their math test scores are a whopping 26% below those of kids in the rest of the state."

I did some poking around and found the Somerville MCAS testing stats online; in the 2003/04 school year, third grade reading scores indicated that 44% needed improvement or were failing; in the 2004/05 school year - these same students, now 4th graders, tested in ELA (english language arts) showed 63% now needing improvement or failing, and 73% needed improvement or were failing math (not tested in 3rd grade).

Just some food for thought, and a hat tip to Sandy for the educational impacts that may be part of the intiatives overall impact not recorded in the results that are focused on BMI z-scores.