Almost a third of people diagnosed as having asthma in Canada did not have the condition when retested using clinical guidelines, a study has found (CMAJ 2008;179:1121-31, doi:10.1503/cmaj.081665).

The study shows “a major problem in our system of asthma care: rather than just being overdiagnosed, asthma is misdiagnosed,” said Matthew Stanbrook, deputy editor of CMAJ, the journal of the Canadian Medical Association, and Alan Kaplan, chairman of the Family Physician Airways Group of Canada, in an accompanying editorial (CMAJ 2008;179:1099-100, doi:10.1503/cmaj.081665).

Such misdiagnosis …