The Edmonton Staging System: Post 2, Discussion
This post is a follow-up to The Edmonton Staging System: Post 1, Basics.
The stated purpose of the Edmonton Obesity Staging System (EOSS) is to predict early death and disease in fat people. It's an attempt to define clinically significant "obesity" without resorting to BMI. But, the conditions it's based on aren't necessarily causally related to weight, so it doesn't really disassociate obesity from BMI. Instead, it associates the diseases of ageing with weight when they occur in fat people. People with BMIs under 30 won't be classified according to the system, even if they have the diseases and conditions that define the stages.
Every disease that kills fat people kills thin people too. Thin people get type II diabetes. Thin people can have high blood pressure, high triglycerides and high cholesterol. Thin people get heart disease and die of heart attacks, all while having BMIs under 25. Many fat people never develop diabetes and/or begin to experience the diseases of ageing at the same time of life that their thin peers do. However, when fat people begin to experience health problems as they age, the Edmonton Obesity Staging System will associate those problems with their weight and consequently weight may be treated as the root cause.
The structure of the EOSS suggests that any health problem that's correlated to higher weight is part of a progressive syndrome called "obesity." In reality, causality is always more complicated than that. For example, family history may play a more important role than weight in diabetes and heart disease, and joint problems may be partly or entirely due to injuries. These factors shouldn't be ignored when another risk factor (high BMI) is present. The way the staging system is structured implies that fat people will inevitably advance within its framework. Conveniently, that's usually true. Why? Because the conditions and diseases associated with a high BMI are also associated with ageing. Almost everyone, fat and thin, moves through the EOSS stages as they age. However, fat people don't inevitably move through them more rapidly. There are fat people who stay at stage 0 or 1 for many decades: 30, 40, or 50 years. An unusually large body is not a progressive disease.
It's not all about weight. If weight were the main factor in health and life expectancy, then we would be seeing much bigger differences between fat and thin people in mortality and morbidity. Hell, thin people would live forever. In reality, fat people don't necessarily die earlier or use significantly more medical resources than thinner people. Maybe the EOSS is partly an attempt to resuscitate the weight based health paradigm in the face of evidence that body mass index (BMI) doesn't do a very good job of predicting mortality or morbidity for individuals - or even populations, except at extremes.
I don't want to get down on the doctors too much. They're not the only ones responsible for the weight based paradigm. In fact, I'm pretty sure that the medicalisation of body size arose in the early twentieth century largely as a response to women's demands for thin, fashionable bodies (and that's a series of posts - or a book - in itself).
To be fair, we're weird here at BFB and in the fatosphere. We're fat people who accept our sizes and want our doctors to do the same. But we are not the majority of fat people.
Many (perhaps most) fat people are desperate to get thin at any cost because of the social stigma, blaming and shaming they're experiencing. Doctors are usually happy to provide "health" as an excuse. The problem is, there is no safe, effective way for most people to lose a significant amount of weight permanently. Every weight loss treatment - from yo-yo dieting to pills to weight loss surgery - has a (sometimes devastating) impact on quality of life and carries significant health risks. The Edmonton Obesity Staging System provides doctors with a way to say "no" to dangerous weight loss treatments for healthy fat people. Why would you provide someone with a normal life expectancy with surgery that could kill her or pills that could damage her heart? This is actually very sane.
The problem is that the staging system creates categories for "good fattie and bad fatties" - it makes healthy fat people into exceptions. However, everyone is going to turn into a bad fattie as they age and nobody, whatever their age or state of health, deserves to have their health problems blamed on their weight and potentially be told to "lose 100 pounds and call me in the morning."
So, if the EOSS is meant to protect healthy fat people from dangerous (and expensive) weight loss treatments based on a rough cost/benefit analysis, then so be it. I just hope that nobody is intending to use it to limit access to treatments for health conditions that are correlated to high BMIs ("hypertension, type 2 diabetes, sleep apnea, osteoarthritis, reflux disease, polycystic ovary syndrome, and anxiety disorder"). Even when the statistics say that a person's BMI is increasing their risk of disease or early death, it doesn't say anything about causation and it doesn't mean that weight loss will have any effect. Sometimes the condition is responsible for the high BMI, not vice versa. And in any case, everyone deserves good medical treatment regardless or what they weigh and regardless of whether or not they lose any weight.
I think all fat people would agree: if we experience a health problem, we'd like our doctors to use the same treatment plan that they would if we were thin. Even people who think that their weight is a problem that can be fixed still don't want to be denied treatment based on it.
Instead of providing a blow-by blow of the research behind the EOSS and the media coverage of it, I'll leave the links with you. There's a lot more analysis that could be done, here. Hopefully these links will help anyone who's interested in following up.
Dr. Sharma's Blog
These are some of the main posts on the Edmonton Obesity Staging System. There are more.
- February 11, 2009: Edmonton Obesity Staging System
- July 28th, 2009: Obesity Classification: Time to Move Beyond BMI?
- August 15, 2011: Setting The Stage For Obesity Staging
- August 16, 2011: Health Is Not Measured In Pounds
- August 18, 2011Should Causality Matter In The Edmonton Obesity Staging System?
- August 19, 2011: Can The Edmonton Obesity Staging System Better Guide Indications for Bariatric Surgery?
- August 22, 2011: Can The Edmonton Obesity Staging System Provide A Path For New Anti-Obesity Drugs?
- August 25, 2011: Public Health Implications of the Edmonton Obesity Staging System
- August 26, 2011: Moving Forward With The Edmonton Obesity Staging System
- September 5, 2011: Bariatric Surgery For Osteoarthritis Of Hips And Knees?
- October 8, 2011: Clinical Assessment: Edmonton Obesity Staging System
- October 21, 2011: Should EOSS Guide Access to Obesity Surgery?
The Arya Sharma article: Using the Edmonton obesity staging system to predict mortality in a population-representative cohort of people with overweight and obesity, August 15, 2011.
The Steven Blair article: Edmonton Obesity Staging System: association with weight history and mortality risk, August 24, 2011.
And... here's the press coverage. The source for these articles will have been this press release from Canada's National Research Council, entitled "System lets health providers better predict which obese patients are at risk for death – and which ones don’t need to lose weight at all"
- Vancouver Sun: Heavy but healthy? New formula slims down definition of dangerously obese.
- City News, Toronto: BMI Not Enough: Edmonton Staging System Gets To The Heart Of Obesity
- Time Healthland: Study: A New Measure of Obesity Helps Predict Early Death
- National Post: Fat not necessarily fatal, new studies find
- CBC News: Obesity score helps predict death risk