Hindsight: Managing Weighty Issues on Lean EvidenceSaturday, August 25, 2012
In 2005, I wrote an article for the Canadian Medical Association Journal (CMAJ), in which I highlighted that fact that in light of the obesity epidemic, physicians and other health care workers will be delivering health care to a growing number of obese and severely obese patients.
“Diagnosing many common medical conditions, although straightforward in nonobese patients, can be fraught with difficulty in morbidly obese people because little is known about the sensitivity and specificity of diagnostic tests in this population. …obtaining imaging studies such as CT or MRI is often impossible for morbidly obese patients because of the size and weight limitations of the machines. Oversized equipment is unavailable in most hospitals. These limitations call for more research into diagnostic algorithms, tests and reference ranges for morbidly obese patients, to avoid misdiagnoses and to ensure optimal care.”
I also noted that with the exception of ‘weight-loss studies’, people with obesity are generally underrepresented in clinical trials.
“As a result, the majority of clinical practice guidelines, even for conditions commonly found in obese patients (e.g., hypertension, diabetes mellitus, asthma, ischemic heart disease, venous thrombosis and neuropsychiatric disorders) fail to make specific recommendations for patients with morbid obesity that go beyond a rather general appeal for weight loss. This issue is far from trivial, as obesity significantly affects the pathophysiology and pharmacodynamic response in a multitude of medical conditions. For example….gastroesophageal reflux disease, where the pathophysiology in obese patients (increased intra-abdominal pressure, hiatal hernia, vagal abnormalities) may be distinctly different from that in nonobese patients. Responses to medications may be different, as metoclopramide may fail to decrease gastric volume or raise pH in obese patients. Similarly, although self-reported asthma is more frequent at higher BMI levels, obese individuals paradoxically are at lowest risk for significant airflow obstruction, and much of the respiratory symptoms may indeed be due to nocturnal aspiration of gastric reflux. Thus, asthma not only may be overdiagnosed in the obese population but, if present, may require a different approach to management.”
I also commented on the need for studies that examine the effects of excess weight on pharmacokinetics and pharmacodynamics of medications commonly used in obese patients.
“Virtually all existing diagnostic criteria and algorithms will need to be revalidated in the obese population, and where physical limitations hinder the use of diagnostic imaging technology, new strategies will have to be developed to deal with very obese people…. In short, most of what we know about medicine will need to be re-evaluated to ensure optimal medical care of obese patients.”
In the seven years that have passed since I wrote this article, we have seen a vast increase in the study of obesity, including studies specifically addressing many of the issues I highlighted in this commentary.
However, we are still far from fully appreciating the impact of the obesity epidemic on medical practice and in many instances, managing obese patients can be better likened to ‘muddling through’ than to a sound evidence-based approach to medical practice.
Training in obesity management or bariatric care is still not a mandatory requirement for graduating from medical school or obtaining your medical license. We are still graduating health professionals, who know more about calcium homeostasis than about energy homeostasis.
If you have experienced problems with diagnostic procedures or treatments because of your size, I’d certainly love to hear about them.