Address unknown — or at least uncertain
CMAJ 1998;158:585
The article "Recent trends in infant mortality rates and proportions of low-birth-weight live births in Canada" (CMAJ 1997;157[5]:535-41 [abstract / résumé]), by Drs. K.S. Joseph and Michael S. Kramer, and the related editorial "A warning from the cradle?" (CMAJ 1997;157[5]:549-51 [full text / résumé]), by Dr. Graham Chance, are relevant to planners and researchers in the population health field, highlighting as they do some serious errors in birth weights in the Ontario vital statistics data and given the consequences of such errors for surveillance of low-birth-weight births in Canada.
Another serious problem has been discovered by health unit epidemiologists working with information supplied by the Public Health Branch of the Ontario Ministry of Health. In these records the place of residence of the mother was coded inaccurately or inconsistently, making it impossible to obtain correct counts of live births by geographic area.
To illustrate the error, we compared 2 sources of information for 1994 births, both obtained through the Ontario Ministry of Health: vital statistics birth data for which place of residence was given as within the metropolitan Toronto area and hospital discharge data from the Canadian Institute for Health Information (CIHI) for live births to women residing in Metropolitan Toronto (Table 1).
Although the total number of Metro Toronto births is similar for the 2 sources, the differences among the 6 municipalities are substantial. Similar differences have been found in some rural areas of Central East Ontario. Which figures are correct? And which should be used to support local planning?
In a letter entitled "Error corrected, conclusions the same" (CMAJ 1997;157[6]:646-7), Indira Singh of the Ontario Ministry of Consumer and Commercial Relations and Janet Hagey of Statistics Canada acknowledge the birth weight errors in Ontario vital statistics data. They replicate Joseph and Kramer's analysis with corrected data and conclude that there has been a statistically significant increase in low-birth-weight births in Ontario in recent years.
Although this may be true at the provincial level, the apparent errors in geographic coding make it impossible for local health authorities to identify the specific areas where low birth weight is a problem and to take the appropriate remedial action.
Because this information is extremely valuable to health researchers and planners, efforts should be made to set national standards for the collection, management and reporting of these data, so that trends in reproductive health outcomes can be followed at the national, provincial and local levels. Without good local data, the integrity of health planning and program evaluation is jeopardized.
It appears that the time has also come to consider whether the collection and management of such data should be transferred from the provincial Ministry of Consumer and Commercial Relations to the Ministry of Health.
John J. McGurran, MSc
Director
Central East Health Information Partnership
Newmarket, Ont.
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