Treating a medical mosaic, doctors develop a new appreciation for the role of ethnicity in disease

Treating a medical mosaic, doctors develop a new appreciation for the role of ethnicity in disease

The Globe and Mail
Toronto, Canada

Dakshana Bascaramurty, Reporter

Baby X is born in a Canadian hospital and her tiny, wrinkled body is placed on a scale that reads 3,061 grams, or 6 pounds and 12 ounces.

Things can go one of two ways for Baby X, whose parents are immigrants from India.

According to the standard birth-weight curves used in Canada, which are modelled after norms for Caucasian newborns, this baby could be labelled as underweight, a classification that comes with a higher risk of death and lower cognitive ability. She could be subjected to a battery of unnecessary tests and follow-ups. Her concerned mother might overfeed her in hopes of speeding up her growth.

Or, if a new birth-weight curve developed at Toronto’s St. Michael’s Hospital – one that takes into account a wide range of ethnicities – is used, Baby X will be classified as having a perfectly normal weight and will be sent home. South Asian newborns are typically smaller than those of many other ethnicities.

It’s just one example of why there is a move in Canada and other countries to collect data on their diverse populations to deliver better patient care.

Doctors and researchers are putting greater stock in ethnicity as a variable in health outcomes. A large body of research suggests certain groups are at a higher genetic risk for particular diseases. And physiologically, what is accepted as “normal” and “healthy” varies between ethnicities.

But there are no universal standards or terms of reference used to classify ethnicity, which has made it a highly fraught subject. Some say it shouldn’t be considered a variable at all, arguing that the link between ethnicity and health is manufactured. The Canadian Institute for Health Information doesn’t collect data on ethnicity, and the Canadian Medical Association has no formal policy on the best way to classify the diverse backgrounds of Canadians.

Joel Ray, who led the St. Michael’s Hospital team that developed the new newborn birth-weight curve, is baffled that an old model developed in 1969 based on the weights of 300 Caucasian newborns in Montreal – a population unreflective of modern Canada – is still used in some parts of the country. In a study published Wednesday in the Journal of Obstetrics and Gynaecology Canada, his team analyzed 760,000 live births in Ontario and, by their measure, more than one in 10 South Asian babies was at risk of being misclassified if one of the standard Canadian birth-weight curves was used.

“They’re completely archaic – there’s no other sweet word for it,” Dr. Ray said.

Dr. Ray previously studied rates of gestational diabetes among women of various ethnic groups and found South Asians had the highest risk levels, followed by those from East Asia and the Middle East. Previous studies have lumped these three groups together under the catch-all category “Asian” – missing the heterogeneity within.

“You may as well call them human if you’re going to call someone Asian,” he said…

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