Dr. Sharma's Obesity Notes

While there is no doubt that today’s kids on average are heavier than ever before, the question of how best to measure obesity in kids, and perhaps even more importantly, how to best determine the health impacts of excess weight remains unresolved.

As in adults, population studies generally use anthropometric measures such as growth curves or body mass index, but these measure, as in adults, are rarely that useful when it comes to determining the individual risks (if any) associated with excess weight.

Nevertheless, such measures, that apply to populations, although not diagnostic, may well be useful in identifying individuals who may warrant closer examination and follow-up.

A paper by Lisa Kakinami and colleagues from McGill University, Monteal, published in the Canadian Medical Association Journal, now examines the relationship between different growth curve definitions of excess weight and cardiometabolic risk factors in kids.

Specifically, the authors compare the two widely used reference standards, the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) growth curves, which have different definitions of overweight and obesity, in a representative population of 2466 boys and girls aged 9, 13 and 16 years in Quebec.

Despite different definitions of overweight and obesity, both the WHO and CDC growth curves generated virtually identical receiver operating characteristic (ROC) curves for individual or combined cardiometabolic risk factors. Small differences in specificity and sensitivity for detecting risk between the two approaches were deemed negligible.

Thus, the researcher conclude that:

“The WHO growth curves show no significant discriminatory advantage over the CDC growth curves in detecting cardiometabolic abnormalities in children aged 9-16 years.”

This of course, still leaves us with the problem of having to make clinical decisions about individuals. This is where the reported higher sensitivities (by 0.6%-8.6%) and lower specificities (by 2.6%-4.2%) of the WHO curves vs. CDC curves, still means that clinicians have to look at each kid individually to decide the appropriate course of intervention.

It is therefore perhaps of interest to note that the paediatric obesity working group within the Canadian Obesity Network (TROPIC) is currently working on adapting the adult Edmonton Obesity Staging System (EOSS) for use in kids and adolescents.

AMS
Leipzig, Germany

Kakinami L, Henderson M, Delvin EE, Levy E, O’Loughlin J, Lambert M, & Paradis G (2012). Association between different growth curve definitions of overweight and obesity and cardiometabolic risk in children. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne PMID: 22546882

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Never mind that it is usually impossible to infer causality from observational studies or, even if significant associations are noted, to predict what may or may not happen, when one of the variables is targeted (as in an intervention). It is also worth noting that many common stereotypic assumptions we make about what may or may not be driving the obesity epidemic continue to be challenged by the actual data on these issues.

A good example of this state of affairs is the recent paper by Valerie Carson (a former CON Bootcamper) and Ian Janssen (an enthusiastic Bootcamp faculty member), from Queens University, Kingston, Ontario, published in Pediatric Obesity on the relationship between TV viewing, snacking, and childhood obesity.

While we are all familiar with the ’stereotypical’ pictures of the fat kid with a bowl of chips with eyes glued to the TV set, suggesting that fat kids are fat because they do little else than watch TV and eating chips (forgetting that skinny kids may do exactly the same), this paper certainly does not easily support this notion.

The study looked at the self-reported snacking and TV viewing habits in relationship to BMI in almost 16,000 youth in grades 6–10 who participated in the Canadian 2009/2010 Health Behaviour in School-Aged Children Survey (HBSC).

Participants reported the frequency of snacking while watching television and the frequency of eating junk food (sweets, soft drinks, baked goods, French fries, potato chips). Total hours per week of television were also calculated.

Although there was certainly a modest positive relationship between television viewing and BMI, this did not seem to be mediated by television snacking or junk food consumption. If anything, the relationship between the latter appeared to be slightly negative.

While there may well be all kinds of methodological and potential confounders of why these findings do not support the ‘hypothesis’ (increased snacking of junk food while watching TV is an important driver of childhood obesity), it certainly appears that this effect, even if it exists, is probably far less powerful than most of us would expect.

Sure, self-reported data (not just in kids) should always be taken with a grain (or teaspoon?) of salt, but then again, one would need to hypothesize that skinny kids are perhaps more ‘truthful’ about reporting their behaviours, something for which there is even less evidence. And yes, the study does not tell us about general snacking or junk food consumption outside of TV viewing but other studies have shown that the commonly held notion that fat kids apparently live on a staple of unhealthy junk foods and soda pop while skinny kids are more likely to be weight-conscious organic vegans, is not exactly true either.

The key learning for me from such studies is merely that much of what we so often assume as the ‘key drivers’ of obesity do not appear to be all that ‘key’, when we look at the actual studies published on these issues (regular readers may recall the results of the Canadian Measurements Survey, which did failed to show that fat kids were any less active than skinny kids).

Obviously, such studies also almost never look at the ‘whys’ (rather than the ‘whats’), as this would be a whole different line of research.

Perhaps, when data does not support the stereotype, it is time to question the stereotype rather than the data.

AMS
Whistler, BC

Carson V, & Janssen I (2012). The mediating effects of dietary habits on the relationship between television viewing and body mass index among youth. Pediatric obesity PMID: 22461393

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Yesterday was the beginning of a three-day Workshop on Paediatric Weight Management in Focus, which offers interdisciplinary training for primary care clinicians with an interest in enhancing the weight management care they provide to children and youth (and their families) with obesity, organized by the Canadian Obesity Network.

The goal of the workshop is to enhance health care professionals’ knowledge, skill, and competence in:

• Behavioral, physiological, psychosocial, and sociocultural factors that impact paediatric obesity

• Clinical assessment methods in pediatric obesity

• Evidence-based intervention strategies for managing paediatric obesity

• Practical tips and tools that can be integrated into everyday practice

The workshop is presented by TROPIC (Treatment and Research of Obesity in Paediatrics in Canada), CON’s paediatric obesity management subnetwork.

The hosts Geoff Ball (U Alberta), Jean-Pierre Chanoine (U British Columbia) and Katherine Morrison (McMaster) are complemented by an array of childhood obesity experts from across Canada, including Annick Buchholz (Children’s Hospital of Eastern Ontario, Ottawa), Arlene Cristall (Shape Down BC, BC Children’s Hospital, Vancouver), Kim Daniel (Sick Kids, Toronto), Carrie Matteson (Simon Fraser U), Jonathan McGavock (U Manitoba), Susan Murphy (Lions Gate Hospital, North Vancouver), Mabel Tan (BC Children’s Hospital) and Michael Vallis (Dalhousie U, Halifax).

Topics include how to have conversations with families, assessing psychosocial factors, sleep, screen time, systemic and family barriers, bias and stigma, dietary assessment, physical exams, readiness to change, youth, defining success, and future directions in paediatric obesity management. The workshop includes hands-on session on complex case management.

Participants are eligible to collect points towards IASO’s Specialist Certification for Obesity Professional Education (SCOPE).

AMS
Vancouver, BC

No doubt obesity is associated with a wide range of health problems affecting almost every organ system.

But acute earache is perhaps not a health problem that immediately comes to mind when we consider the health risks of excess weight.

According to a paper by Stefan Kuhle and colleagues from University of Alberta, School of Public Health, published in the latest issue of Pediatric Obesity, acute middle ear infections (otitis media) may be far more common in obese than in normal weight kids.

This prospective cohort study, linked data from a population-based survey of Grade 5 students (aged 10-11 years) in the Canadian province of Nova Scotia in 2003 with Nova Scotia administrative health data via Health Card numbers.

Relative to normal weight children, obese children had twice as many healthcare provider contacts for severe purative otitis media (ICD9: 382; ICD10: H65-66), incurred more costs per otitis media-related visit ($47 vs. $24) and were two-and-a-half times more likely to have repeated otitis media infections.

There was a significant dose-risk effect with overweight kids fitting nicely between normal weight and obese kids in terms of increased risk.

This risk was independent of a range of socioeconomic factors, history of breastfeeding, presence of an allergic disorder or chronic adenoid/tonsil disorders.

Although, association does not prove causality, it is worth noting that this finding has considerable biological face value.

Thus, the authors provide the following possible explanation for this relationship:

“…obesity has been linked with low-grade systemic inflammation, which may produce a milieu that increases the risk of otitis media or lead to chronic otitis media. Alternatively, gastroesophageal reflux, which is seen more frequently in individuals with higher BMI may enter the middle ear through the Eustachian tube and cause otitis media. Finally, in obese individuals fatty tissue may accumulate around the Eustachian tube thereby compromising ventilation of the middle ear.”

As the authors also point out, this finding may have considerable public health implications:

“Acute otitis media is the second most common reason for visits to a family physician, accounting for 10– 15% of all childhood visits. Recurrent otitis media may result in long-term sequelae such as learning disability, impaired linguistic development or hearing disorder, or sleep apnoea because of the development of chronic adenoid/tonsil disorder.”

But the cost implications are also worth noting:

“We were able to show that the per capita physician costs for otitis media between 2001 and 2006 were 92% higher ($47 vs. $24) in obese children compared with normal weight children. This cost differential is second only to that of chronic adenoid/tonsil disorder (230%) out of the 10 childhood disorders examined”

While the study does not provide any insights into whether reducing childhood obesity would reduce ear infections or whether or not obese kids need to adopt any other precautions to avoid earaches, it certainly points to an under appreciated risk factor for this common and excruciatingly painful condition.

AMS
Edmonton, Alberta

Kuhle S, Kirk SF, Ohinmaa A, Urschitz MS, & Veugelers PJ (2012). The association between childhood overweight and obesity and otitis media. Pediatric obesity, 7 (2), 151-7 PMID: 22434755

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Kristi Adamo, PhD, Research Scientist, CHEO, Ottawa

Given the rather enthusiastic response to yesterday’s post on how the focus on varsity sports may undermine efforts to get the whole student population moving, here is a guest post from Kristi Adamo, one of my colleagues from Ottawa:

Just thought I would chime in as an ex-varsity athlete. My husband and I were both University varsity athletes (that is how we met) and it is in part what made us who we are and the type of parents we have become. Because we played high level sport most of our lives we are quite realistic in our expectations of our children and we feel we have insight as to what is important for them to learn and what can wait. We are knowledgeable enough to recognize that our children may never be like the ‘great one’.

While we both believe a certain level of competition is healthy, our experiences have taught us that encouraging active behaviour and the development of motor skills through a variety of fun activities is much more important than knowing all the rules of a complex game, or scoring the most goals, baskets etc… We have made efforts to teach our girls that physical activity is part of a healthy lifestyle- just like eating green leafy vegetables! They recognize that mommy and daddy both play sports because they are fun and keep us fit so that we can live healthy longer. My 4 year old could tell you at length why this is important …

While I do not condone the American model regarding the elitism of varsity sport and the gift of graduation to those who contribute to a National championship (let’s be honest we know this happens and there are some dumbasses who get a degree because of their ability to draw in the crowds), in my opinion doing away with varsity sport in order to encourage more for the masses is NOT a viable solution and may further ostracize those who are not ‘talented’ if we pool all skill levels together… thus we should not throw out the baby with the proverbial bathwater.

I can say with some degree of certainty that the Canadian athletics scene is far different that that south of the border but any PE teacher who focuses on one sport is clearly not trained to be a PE teacher and all and herein lies the problem. I understand why children, like the one quoted, would opt not to participate.

Unfortunately, I think that the popularization of professional sport and the money and lifestyle tied to this has done us a severe disservice. While I am no expert, I understand that in the US some of the college coaches make more money than any other employee of school- and that often team endorsements are higher than the grant funding brought in by all research departments. Perhaps we need to think about this aspect and what kind of message this is sending…

While I will not deny that there are drawbacks to elite sport, high level sport can positively influence many aspects of one’s life and contribute to the development of very fine individuals who have leadership skills, a great work ethic, who strive for excellence, are diligent team players who know how to compromise when necessary, have a degree of humility (recognizing there is always someone more talented) and obligation, and can be an excellent role models.

Kristi Adamo, PhD, is currently a Research Scientist with the Healthy Active Living and Obesity Research group at the Children’s Hospital of Eastern Ontario Research Institute and an Assistant Professor in Human Kinetics and the Department of Paediatrics at Ottawa University. Her research interests include prevention of childhood obesity and its metabolic consequences, lifestyle intervention, and life course of obesity, specifically early determinants. She is also an avid athlete (hockey, soccer, volleyball, running).

AMS
Regina, Saskatchewan