When is a Condition Obesity Related?Friday, October 9, 2009
Yesterday, I blogged about the proposed Edmonton Obesity Staging System. This prompted a number of comments and questions.
Here a few quick answers regarding the Staging System:
1) The terms mild, moderate, and severe are of course subjective. In some cases there are objective measures (e.g. valid scales) to assess the severity of symptoms but in other cases, this call is really to be made by the medical professional based on the interview, physical exam and other assessments.
Although there may be some variability in judgement between clinicians, hopefully, the inter-rater reliability will not be too far off.
2) What is the definition of obesity related comorbidity?
Unfortunately, excess weight can lead to a wide range of health problems. However, it is often not entirely clear whether or not a specific problem in a given patient is really entirely weight related.
Thus for e.g. although obesity is a common cause of fatty liver disease, there are many other factors that can lead to excess accumulation of liver fat. Often it may only be possible to tell if a problem is obesity related when the problem actually gets better or even disappears with weight loss.
I generally suggest that in order to be considered obesity related, a problem has to meet at least two of the following three criteria.
1) There is good epidemiological evidence that the condition is more common in people with overweight or obesity.
2) There is evidence that the condition actually gets worse with weight gain and/or better with weight loss.
3) There is a plausible biological link between the condition and excess weight.
It the condition meets at least two of these criteria, it may be fair to assume that it is likely weight-related unless there is substantial reason to suspect another cause.
Once again, the final proof that a specific condition is in fact weight-related can only come from the demonstration that the condition actually does get better with weight loss (This of course does not apply to conditions like obesity related cancers, which, once established are unlikely to disappear or get better with weight loss).
Hopefully, these explanations provide some clarification. Several research projects are currently underway to further validate this staging system to increase its utility in medical research and practice.
Once again, all ideas and comments are greatly appreciated.