title: Estimating chronic disease rates in Canada: which population-wide denominator to use?
abstract: BACKGROUND
  Chronic disease rates are produced from the Public Health Agency of Canada's Canadian Chronic Disease Surveillance System (CCDSS) using administrative health data from provincial/territorial health ministries. Denominators for these rates are based on estimates of populations derived from health insurance files. However, these data may not be accessible to all researchers. Another source for population size estimates is the Statistics Canada census. The purpose of our study was to calculate the major differences between the CCDSS and Statistics Canada's population denominators and to identify the sources or reasons for the potential differences between these data sources.
  
  
  METHODS
  We compared the 2009 denominators from the CCDSS and Statistics Canada. The CCDSS denominator was adjusted for the growth components (births, deaths, emigration and immigration) from Statistics Canada's census data.
  
  
  RESULTS
  The unadjusted CCDSS denominator was 34 429 804, 3.2% higher than Statistics Canada's estimate of population in 2009. After the CCDSS denominator was adjusted for the growth components, the difference between the two estimates was reduced to 431 323 people, a difference of 1.3%. The CCDSS overestimates the population relative to Statistics Canada overall. The largest difference between the two estimates was from the migrant growth component, while the smallest was from the emigrant component.
  
  
  CONCLUSIONS
  By using data descriptions by data source, researchers can make decisions about which population to use in their calculations of disease frequency.
authors: Centre for Chronic Disease Prevention, Public Health Agency of Canada, Ottawa, Ontario, Canada.
authors: J
authors: J
authors: Ellison
authors: Department of Public Health Sciences, School of Public Health, University of Alberta, Edmonton, Alberta, Canada.
authors: C
authors: C
authors: Nagamuthu
authors: Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors: S
authors: S
authors: Vanderloo
authors: Centre for Chronic Disease Prevention, Public Health Agency of Canada, Ottawa, Ontario, Canada.
authors: B
authors: B
authors: McRae
authors: Centre for Chronic Disease Prevention, Public Health Agency of Canada, Ottawa, Ontario, Canada.
authors: C
authors: C
authors: Waters
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada / Q000453:epidemiology; D002423:Cause of Death; D019352:Censuses; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease / Q000453:epidemiology* / Q000401:mortality; D016208:Databases, Factual / Q000706:statistics & numerical data; D003920:Diabetes Mellitus / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007348:Insurance, Health / Q000706:statistics & numerical data*; D008875:Middle Aged; D011153:Population; D015995:Prevalence; D055815:Young Adult
keywords: Canadian Chronic Disease Surveillance System; administrative health data; census; denominator; disease surveillance; measures of disease frequency; population estimates Canada