Hospital separation records are the most comprehensive and accessible source of morbidity information. Other components of morbidity include visits to emergency rooms and physicians, but these data are generally unavailable for analysis.

A separation may be due to death, discharge home, or transfer to another facility.

Co-morbidity contributes uncertainty to classifying the most responsible diagnosis.

Since a person may not be hospitalized or may be hospitalized several times for the same disease or injury event, or discharged from more than one hospital (when transferred) for the same injury event, hospitalization data provide only a crude measure of the prevalence of a cause.

Data are influenced by factors that are unrelated to health status such as availability and accessibility of care, and administrative policies and procedures. This may influence comparisons between areas and over time.

Data are collected based on location of hospital but are generally analyzed by the residence of the patient.

Data can be analyzed by fiscal or calendar year. In this report calender year was used exclusively in the analysis.

Ontario residents treated outside of the province are excluded. Less than 0.5% of all procedures performed for Ontario residents are out-of-province; however, areas bordering other provinces may be more affected.

Rates and proportions based on counts less than 5 must be suppressed.

· Reference: Canadian Institute for Health Information, Provincial Health Planning Database, Ontario Ministry of Health, January 2000.