An obesity scoring system developed in Edmonton to help predict the risk of dying for overweight and obese people could be used to prioritize patients for weight-loss surgery.

The Edmonton Obesity Staging System (EOSS) is modeled on similar scores used to predict the extent and severity of other diseases such as a cancer, heart disease and mental illness. 

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The new model emphasizes how at-risk the patient is, not how much they weigh, says Dr. Arya Sharma.

One in five Canadians is obese, a label given to anyone whose body mass index is greater than 30 on a measure of height relative to weight.

The new scale includes five stages of obesity based on traditional measurements such as body mass index and waist-to-hip ratios, as well as clinical measurements of medical conditions tied to obesity, such as Type 2 diabetes, hypertension and heart disease.

In Monday's issue of the Canadian Medical Association Journal, Dr. Arya Sharma of the University of Alberta and his co-authors used the tool to predict death with data from a U.S. population survey of 8,143 people who were followed for 16 years. About 77 per cent of them were overweight or obese.

5 stages of obesity scale

The obesity scale has five stages. Criteria include:

Stage 0: No apparent obesity-related risk factors (e.g., high blood pressure, cholesterol and/or glucose levels), no physical symptoms or limitations.

Stage 1: Subclinical risk factors such as borderline hypertension, mild physical symptoms such as shortness of breath with moderate exertion.

Stage 2: Presence of obesity-related chronic disease such as hypertension, Type 2 diabetes, sleep apnea and osteoarthritis with moderate limitations on activities of daily living.

Stage 3: Established end-stage organ damage such as heart attack or stroke with significant functional limitations.

Stage 4: Severe disabilities from obesity-related chronic diseases.

Source: CMAJ

The findings suggested the scoring system was a strong predictor of increasing mortality risk in both the overall population and among those eligible for weight-loss treatment known as bariatric surgery.

"Body mass index, which is widely used to categorize and assess patients with obesity, only measures how big you are — not how sick you are," Sharma said in a release.

"The importance of EOSS is that it puts an emphasis on individualized treatment needs depending on how at-risk the patient is, not how much they weigh. With a single piece of paper, physicians can rapidly assess needs, and as importantly, prioritize treatment resources such as surgery."

Prioritizing patients with higher scores and mortality risk may help maximize the benefits of surgery, the researchers said.

A related study published online Monday in the journal Applied Physiology, Nutrition and Metabolism categorized 6,000 obese Americans based on the Edmonton system and compared their risk of dying to 23,000 lean counterparts over a 16-year span.

Promote weight maintenance

Compared with those with normal weights, patients in Stage 2 or 3 were at higher risk of cardiovascular disease and death, but patients in Stage 0 or 1 were not, Prof. Jennifer Kuk of York University's School of Kinesiology & Health Science in Toronto and her co-authors found.

"Obese patients, particularly in EOSS stages 0 and 1, may be better served if physicians promoted weight maintenance, as opposed to weight loss, as it remains to be seen whether individuals in EOSS stages 2 and 3 will benefit from weight loss," the researchers said.

Factors such as weight at age 21, cardio respiratory fitness, reported dieting and fruit and vegetable intake were each associated with a higher risk for Stage 2 or 3.

"It shows that you have to have a healthy lifestyle," Kuk said in an interview. "You have to engage in physical activity, but you might not have to focus on losing weight and be obsessed with the scale."

Sheryl Zaparozan of Edmonton is at Stage 1. Sharma tells her that with diet and exercise that she could become a stage 0, a revelation that's Zaparozan said has helped her self-esteem.

After trying diet pills, protein shakes and meal replacements to help manage her weight, Zaporozan now walks every day.

"What weight that may be healthy for you may not be healthy for me," she said.

The study was funded by the U.S. National Institutes of Health.

With files from CBC's Briar Stewart and Melanie Glanz