Study: Medically unexplained physical symptoms

A substantial number of Canadians report symptoms of conditions that cannot be definitively identified through physical examination or medical testing.

These are known as "medically unexplained physical symptoms," and they characterize conditions such as chronic fatigue syndrome, fibromyalgia, and/or multiple chemical sensitivity.

This new Health Reports study, "Medically unexplained physical symptoms," reveals that in 2003, 5% of Canadians aged 12 or older, an estimated 1.2 million people, had at least one of these three conditions.

About 1.3% of the population reported chronic fatigue syndrome, which is characterized by extreme tiredness.

About 1.5% reported fibromyalgia, which involves pain lasting three months or more in at least 11 of 18 specified areas.

About 2.4% reported multiple chemical sensitivity. People with this disorder develop a variety of symptoms when they are exposed to synthetic chemicals in doses that usually have no noticeable effect.

Among individuals with medically unexplained physical symptoms, about 14% had at least two of the three conditions.

Data from the 2003 Canadian Community Health Survey show the percentage of women with each of the three conditions was about double that of men.

As well, the proportion of people reporting at least one of the three conditions rose from 1.6% at ages 12 to 24 and peaked at 6.9% at ages 45 to 64. Among seniors, 6.0% were affected.

Each of the three conditions was more common among people in lower income households than among those in the highest income households.

According to the 2002 Canadian Community Health Survey, 21% of people with medically unexplained physical symptoms had at least one psychiatric disorder, such as depression, bipolar I disorder, panic disorder, social anxiety disorder and agoraphobia. In contrast, only 8% of people who did not have these unexplained symptoms had one or more psychiatric disorders.

The prevalence of mental disorders was particularly common among people reporting chronic fatigue syndrome.

More than one-quarter (27%) of people with medically unexplained symptoms needed help with activities such as meal preparation, everyday housework, getting to appointments and running errands. This was four times the proportion of only 7% among people who did not report any of the conditions.

Relatively large proportions of people with medically unexplained physical symptoms sought assistance from conventional and alternative health care providers.

In 2003, 22% of people with these conditions reported having consulted general practitioners more than 10 times in the year before the survey, compared with just 7% of people who did not report these conditions.

Definitions, data sources and methods: survey numbers, including related surveys, 3226 and 5015.

The article "Medically unexplained physical symptoms" is included in the latest edition of Health Reports, Vol. 18, no. 1 (82-003-XWE, free), now available from the Publications module of our website.

For more information, or to enquire about the concepts, methods or data quality of this article, contact Jungwee Park (613-951-4598; Jungwee.Park@statcan.gc.ca), Health Statistics Division.

For more information about Health Reports, contact Christine Wright (613-951-1765; Christine.Wright@statcan.gc.ca), Health Statistics Division.