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Obesity: The Canadian perspective
Obesity: The Canadian perspective Lymphedema related to the growing rate of obesity is under-recognized and undertreated
Obesity rates in Canada have been increasing. Rates reported by Obesity Canada, which combines overweight and obesity categories, were 49% in 1978, 59% in 2004 and 64% in 2017 1 . Canadian statistics use the Body Mass Index (BMI) system calculated from height and weight in kg/square metre (see Table 1).
TABLE 1 Canadian Obesity Categories
BMI (kg/m 2 ) < 18
18 – 24.9 25 – 29.9 30 – 34.9 35 – 39.9 ≥ 40
Category Underweight Normal Overweight Class I Obesity Class II Obesity Class III Obesity (Morbid Obesity)
The background
According to Stats Canada, obesity rates (Class I and above) from actual anthropomorphic measures steadily increased from 23.9% of the population in 2009 to 28.1% in 2015 but remarkably decreased to 26.9% in 2017 2 . There are many different Stats Canada reports, some from actual height and weight measures and others from self-reported measures. Child hood obesity rates have also recently been reported as lower. Overweight and obesity combined reported by Stats Canada in 2015 as 61.3%. More than half of these were classed as overweight. At that time 782,500 were reported as morbidly obese. These figures were from measured data. Canadian Class III obesity rate was reported in 2005 at 2.1% climbing to 4% in the 2016 census. Rates have been reported as stabilizing.
The lymphatics are intimately associated with arteries and veins and function must be considered together. The lymphatics mobilize all excess tissue fluid. Lymphatics also have an immune function and a key role in fat metabolism. Lymphatics absorb fat from the digestive system and transport it as chyle to the circulatory system. It is known that lymphedema and fat metabolism are linked 3 . Obesity can lead to increased lymphatic dysfunction and subsequent inflammation. This is linked to increased fibrosis of the tissue and increased adipose tissue deposition. The fat cells deposited are different from normal fat cells, being much larger. Mechanisms are a subject of much research.
There is an association between obesity and lymphedema. In 2015 a review of 326 lymphedema patients treated at the Parkwood Wound Management clinic, 45% were found to be morbidly obese 4 . It is conservatively estimated that over half those with a BMI ≥ 40 will have lymphedema and if BMI ≥ 50 the
David Keast, MD is the Medical Director of the Chronic Wound Management Clinic at the Parkwood Institute in London, Canada. He is Clinical Adjunct Professor of Family Medicine, Schulich School of Medicine and Dentistry, Western University (London) and an Associate Scientist, Lawson Health Research Institute, Parkwood Institute Research. He is Co-Chair of the Canadian Lymphedema Framework. risk rises to 100%. Using this figure, the CLF estimated that the number with lymphedema due to obesity is 570,000 in Canada.
By David Keast
Obesity and lymphedema—two studies
In 2019, patients with lymphedema attend ing two Canadian clinics were reviewed in independent studies to determine levels of obesity. Shallwani et al reviewed 178 patients suspected of having lymphedema referred over a two-year period to the McGill University Health Centre (MUHC) Lymphedema Clinic 5 . Patients mostly had upper extremity lymphedema and were cancer-related. BMI data demonstrated that 39.1% were overweight, 21.9% had Class I obesity, 6.7% Class II and 10.7% Class III. Also, in 2019 the Parkwood Institute Chronic Wound Management and Lymphedema Clinic under took a chart review of all lymphedema patients seen since 2011 to determine levels of obesity. Patients mostly had lower extremity lymphede ma of non-cancer etiology. Comparison of the two studies is shown in Table 2. The results
TABLE 2
Comparison of Two Canadian Studies to determine Obesity Levels in Lymphedema Patients
Characteristic
Total Charts BMI recorded No BMI Average Age Male Female
Shallwani et al 7
429 178 251 61.0 15.7% 84.0%
Keast and Janmohammad 735 478 257 68.9 43.0% 57.0%
are compared in Table 3. The characteristics of the patients attending these two Canadian clinics were compared in the recent Canadian LIMPRINT paper as shown in Table 4 6 . The data for the characteristics of the MUHC patients are from a previous study by Shallwani and colleagues 7 and those of the Parkwood patients from a study by Wang and Keast 4 .
When the overweight and obesity categories are combined, the results are greater than the Obesity Canada data of 64% in 2017 for
TABLE 3
Obesity Rates (Percentage)
Characteristic
Underweight Normal Overweight Class I Class II Class III
Shallwani et al 7 0.6 23.6 39.1 21.9 6.7 10.7
Keast and Janmohammad 2.3 11.5 15.6 14.8 15.8 40.5 the general population, with the MUHC clinic at 78.4% and the Parkwood clinic at 86.7%. The patients primarily with upper extremity lymphedema tend to be overweight whereas those with lower extremity lymphedema tend to have Class III obesity. Class III obesity is associated with increased rates of co-morbid conditions such as diabetes and heart disease. Lower extremity patients are also at higher risk of cellulitis. Class III obesity rates in Canada doubled from 2005 to 2016. If the rate contin ues, we can expect to see increased rates of the complications, including increased rates of secondary lymphedema.
Conclusion
Secondary lymphedema related to the growing rate of Class III obesity is under-recognized and undertreated. The treatment of the lymphedema itself as well as the co-morbid conditions constitutes a significant burden on the health care system. Management of these complex patients is a significant challenge. Not only does the lymphedema need to be
Comparison Patient Characteristics Characteristic Shallwani Wang and et al 7 Keast Mean age 61.4 At diagnosis = 66.8
Female Male Cancer Primary Secondary Upper body Lower Body Unilateral Bilateral 85% 15% 81% 7% 93% 51% 45% 74% 25% 52.1% 47.9% 10% 4% 96% 1.2% 99.7% 17% 83%
managed, but also the co-morbid conditions.
Better nutrition, exercise and weight loss
strategies must also to be employed. LP
A full set of references can be found at www.lymphedemapathways.ca
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