However, there was also much agreement that the current criteria for diagnosing this disease, based on BMI criteria alone, has important limitations in that it may over-diagnose a significant number of individuals at no or very little imminent risk from their body fat and (even more importantly) under-diagnose a substantial number of individuals, who may well stand to benefit from anti-obesity treatments.
Thus, as my readers are well aware, I have long called for a redefinition of obesity based on the actual presence of health impairments attributable to abnormal or excess body fat.
It is thus timely that JAMA Internal Medicine has just published a seminal article by Jenny Doust and colleagues on behalf of the Guidelines International Network (G-I-N) Preventing Overdiagnosis Working Group, that provides a framework for anyone proposing changes to disease definitions.
Using a 5-step process that included (1) a literature review of issues, (2) a draft outline document, (3) a Delphi process of feedback on the list of issues, (4) a 1-day face-to-face meeting, and (5) further refinement, the group developed an 8-item checklist of items to consider when changing disease definitions.
The checklist specifically deals with the issues of definition changes, number of people affected, trigger, prognostic ability, disease definition precision and accuracy, potential benefits, potential harms, and the balance between potential harms and benefits.
The authors propose that,
“…the checklist be piloted and validated by groups developing new guidelines. We anticipate that the use of the checklist will be a first step to guidance and better documentation of definition changes prior to introducing modified disease definitions.”
No doubt it would be prudent to consider all of the identified aspects in the checklist, when considering changing the definition of obesity from one based simply on BMI to a more clinical definition, based on actual impairments in health.
In coming posts, I will consider each of the proposed checklist items and how they may apply to such a change in the definition of obesity.
Hat tip to Dr. Marcela Flores for drawing my attention to this paper
In my opening address to the delegates, however, I emphasised that acceptance of obesity as a chronic medical diagnosis requires modification of the definition of obesity to ensure that people diagnosed with this condition do in fact have significant health impairments that warrant them being considered ‘sick’.
This is where, the current commonly used ‘definition’ of obesity based on BMI breaks down, as it would ‘misdiagnose’ a significant proportion of Canadians with having a ‘disease’, when in fact they may be perfectly healthy. Moreover, the current BMI-based ‘definition’ of obesity would exclude an even larger group of individuals, who may stand to benefit from anti-obesity treatments as having a BMI that is too low.
Let us recall that BMI is really just a measure of size and not a direct measure of actual health.
As discussed in a recent editorial published in OBESITY, we have suggested that it would only take a minor (but important) modification of the current WHO definition of obesity to ensure that this label is only applied to people whose health is in fact affected by their body fat.
Thus, we have suggested that the current WHO definition,
“The presence of abnormal or excess body fat that may impair health.”
be modified to
“The presence of abnormal or excess body fat that impairs health.”
This simple change to the wording would have significant implications in that obesity would move from simply being a term used to describe a risk factor (“may impair health“) to being an actual disease (“impairs health“), with all of its consequences for policy, regulators, healthcare systems, research, and clinical practice.
Before anyone thinks that this would be far too cumbersome or impractical, let us remind ourselves that such diagnostic approaches are standard practice for a wide range of other diseases that require a clinical encounter, laboratory testing, and/or diagnostic imaging for their diagnosis. In fact, there are very few diseases that can be reliably diagnosed with just a single measure or test.
“…in clinical practice, assessing whether or not abnormal or excess weight is impairing someone’s health should not pose a major diagnostic dilemma. In the vast majority of patients, a few interview questions, a brief physical exam, and a short panel of routine lab tests should readily establish (or rule out) the diagnosis of obesity.”
“Of course, there will always be borderline cases in which the signs and symptoms are too vague or too subjective to be diagnostic — but that, again, is not unlike other diseases in which borderline cases may require a more intense work-up or simply a watch-and-wait approach.”
“Moreover, in some cases, it may be rather difficult to establish whether a given health impairment is indeed due to the presence of abnormal or excess body fat. In these cases, it may be prudent to use an ex juvantibus (from Latin, meaning “from that which helps”) approach to confirm or discard the diagnosis of obesity based on whether said signs or symptoms (and not just body weight) respond positively to weight loss treatments.”
Such a redefinition of obesity would likely also have implications for how we apply the Edmonton Obesity Staging System to describe the severity of this disease. Thus, there would no longer be an EOSS Stage 0, as (by definition), these individuals do not have any mental, medical, or functional impairments attributable (wholly or in part) to their body fat. Moreover, EOSS Stage 1, may need to be redefined as “pre-obesity”, thus reserving the term “obesity” only for individuals who have at least EOSS Stage 2 or greater.
As for redefining obesity, let us remind ourselves that,
“Throughout medical history, disease definitions have often been subjected to refinements and alterations, reflecting advances in our understanding of the disease process as well as in diagnostic and therapeutic approaches. A redefinition of obesity based on actual health status would help us refocus our attention on ensuring that obesity treatments reach those who stand to benefit most rather than anyone who happens to exceed a certain size.
As importantly, this redefinition of obesity would also allow individuals,whose health is clearly being impaired by the presence of abnormal body fat, to access obesity treatments regardless of their shape or size.”
Redefining obesity based on clinical assessments would not necessarily mean that we discard BMI entirely from obesity research – it will certainly remain a valid measure for population studies and perhaps even continue its existence as a screening test to identify people likely to have obesity. BMI however, would no longer be used to diagnose this medical disease.
Continuing in my miniseries on arguments in favour of calling obesity (defined as excess or abnormal fat tissue that impairs health) a disease, I turn to the perhaps most important reason of all – access to care.
Currently, few health care systems feel obliged to provide individuals presenting with obesity treatment for their condition (beyond a few words of caution and simplistic advise to simply eat less and move more).
Most health plans do not cover treatments for obesity, arguing that this is simply a lifestyle issue.
In some countries (e.g. Germany), health insurance and health benefit plans are expressly forbidden by law to cover medical treatments for obesity.
Although long established as the only evidence-based effective long-term treatment for severe obesity, many jurisdictions continue to woefully underprovide access to bariatric surgery, with currently less than 4 out of 1,000 eligible patients receiving surgery per year in Canada.
Pretty much all of this can be blamed on one issue alone – the notion that obesity is simply a matter or personal choice and can be remediated by simple lifestyle change.
Declaring obesity a disease can potentially change all of this.
As a disease in its own right, health care systems can no longer refuse to provide treatments for this condition.
In the same manner that no health system or insurance plan can refuse to cover treatments for diabetes or hypertension, no health system or insurance plan should be able to deny coverage for treatments for obesity.
As a chronic disease, obesity care must now be firmly integrated into chronic disease management programs, in the same manner that these programs provide services to patients with other chronic diseases.
How long will it take before this becomes accepted practice and funding for obesity treatments rises to the level of funding currently available for treating other chronic diseases?
That, is anyone’s guess, but no doubt, declaring obesity a disease finally puts patients living with this condition on an equal footing with patients living with any other chronic disease.
Next, in my miniseries on arguments I commonly hear against the notion of calling obesity a disease, is that it is “just a risk factor” for other diseases.
This may be true, if you just (wrongly) considered elevated BMI as your definition of obesity, because no doubt, people with higher BMI levels carry a higher risk for obesity related complications including type 2 diabetes, sleep apnea, fatty liver disease, hypertension – just to name a few. (Note that increased risk is not the same as actually having the condition!).
However, when you use the actual WHO definition of obesity, namely, “accumulation of excess or abnormal fat that impairs health”, obesity is no longer just a risk factor – it is now (by definition) impairing your health, which makes it far more than just a risk factor.
So while someone with a BMI of 35 may be at risk of developing obesity (not the same as having it), when their excess fat actually starts impairing their health, it de facto becomes a disease in its own right.
Even then, one might argue that obesity itself is not the disease, rather the complications of obesity are the real disease.
This notion is both right and wrong.
There are many conditions that are both diseases in their own right as well as risk factors for other diseases or complications.
Take type 2 diabetes for instance – it is both a disease in itself but also a risk factor for coronary heart disease or end-stage kidney disease.
Take hypertension – a disease in its own right but also a risk factor for strokes and heart attacks.
Take gastro-oesophageal reflux disease, which is also a risk factor for Barrett’s disease and oesophageal cancer.
Take fatty liver disease, which is also a risk factor for cirrhosis.
Gall bladder stones, which is also a risk factor for pancreatitis.
Multiple sclerosis, which is also a risk factor for neurogenic bladder and pyelonephritis.
The list goes on and on.
So just because obesity is also a risk factor for a wide range of other medical problems, it does not make obesity any less of a disease in its own right.
When excess or abnormal body fat affects health – it’s a disease. When it doesn’t, it’s at best a risk factor.
That, is perhaps a subtle but important distinction.
Continuing in my miniseries on arguments I hear against calling obesity a disease, I now discuss the objection, that doing so promotes a sense of helplessness or even hopelessness in people who carry extra weight.
First of all, as noted previously, carrying extra weight is NOT the definition of obesity. For someone to have obesity they need to be carrying weight that is actually due to excess or abnormal fat tissue AND there has to be some negative impact of that fat tissue on their health – otherwise they do not have obesity!.
That said, I am not sure how calling obesity on changes anything in terms of helplessness or hopelessness.
Yes, the effective options to better manage obesity are limited and most people will likely struggle simply not to gain even more weight – but that fact doesn’t change whether you call obesity a disease or not.
Indeed, there are many diseases for which we lack effective treatments (e.g. Alzheimer’s disease, multiple sclerosis), this does not make any of them any less of a disease.
As for hopelessness, just because you are diagnosed with a chronic disease doesn’t mean everything is hopeless.
In fact, there are many people living with chronic diseases that are controlled and well managed (e.g. diabetes, hypertension, sleep apnea), who do just fine (with treatment) and go on to live long and productive lives.
Obviously, we need better treatments for obesity but even without those, people living with obesity can change the course of their disease by identifying and addressing the root causes of their weight gain (e.g. depression, PTSD, emotional eating, etc.) and adopting behaviours, which even if not resulting in any noticeable weight loss, can markedly improve their health and well-being.
Again, whether you call obesity a disease or not is completely irrelevant to whether or not you feel helpless or hopeless – the management approach would be the same, except that hopefully it will shift attention to a chronic disease strategy that requires long-term sustainable management rather than an acute intervention that is unsustainable.
If we are serious about providing patients with help and hope, let us get serious about finding and providing better treatments for this disease.