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10 Canadian Congenital Anomalies Surveillance System (CCASS)

Canadian Congenital Anomalies Surveillance System (CCASS)

Original source: Canadian Institute for Health Information (CIHI)
Distributed by: Public Health Agency of Canada (PHAC)
Suggested citation (see Data Citation Notes): CCASS [years], Public Health Agency of Canada, Extracted: [date]  

Data Notes

  • The Canadian Congenital Anomalies Surveillance System (CCASS) is an ongoing and passive population-based congenital anomalies surveillance system. The system was established in 1966 as a result of the thalidomide tragedy. CCASS is administered by the Maternal and Infant Health Section of the Public Health Agency of Canada (PHAC). Canada reports national CCASS data to the International Clearinghouse for Birth Defects Surveillance and Research.
  • In 2004, the birth prevalence of identified congenital anomalies (CAs) in Canada was 4.8% (or 479.8 per 10,000 total births). The prevalence of CAs at birth is defined as the number of liveborn or stillborn babies identified as having at least one CA, expressed as a proportion of the total number of live births and stillbirths (in a given place and time). (1)
  • Currently, the Canadian Institute of Health Information (CIHI) Discharge Abstract Database (DAD) is the primary source of data for most provinces, with exception of Alberta and Quebec. Registered stillbirths (≥20 weeks gestation or ≥500 grams) and live births from 20 weeks are captured.
  • Historically, CA cases resulting in spontaneous and therapeutic abortions prior to 20 weeks have not been included in CCASS. With the integration of BORN Ontario data with CCASS beginning in 2012, these prenatally detected cases of CAs ending in pregnancy termination will begin to be captured.  
  • Until 2000, CCASS captured CA cases diagnosed in acute care hospitals in infants from birth through the first year of life. Since 2001, CIHI no longer released birth dates to PHAC and ascertainment has been limited to 30 days following birth. Because the majority of CAs, particularly the most severe anomalies, are generally diagnosed in the first month of life, this change in CIHI reporting is not expected to greatly impact the completeness of CCASS data for most anomalies.
  • In 2008, PHAC introduced the Canadian Anomalies Surveillance Enhancement initiative to support enhanced provincial and territorial congenital anomalies surveillance systems.
  • As part of this initiative, BORN Ontario will be submitting CA data for Ontario to CCASS in early 2012 and on an annual basis moving forward. This data will include a set of 16 CCASS national variables with ascertainment up to 1 year after birth. BORN Ontario will ascertain cases from live births, stillbirths and terminations in which a fetal or CA has been detected in hospital.
  • Since infants with CAs are often hospitalized more than once in their first month, PHAC processes the CCASS data to identify duplicates. Duplicates are identified by matching records of the baby's admission date, age in days, sex, province issuing the health care number, postal code or geocode, medical conditions, and scrambled health insurance number. Because there are no unique identifiers to ensure accurate identification of duplicates, matching is imperfect. In addition, incomplete records make matching less accurate and may result in over-counting of the number of CA cases. The margin of error is thought to be small and equally distributed across Ontario.
  • The CCASS system captures ICD-10-CA coded diagnoses and reports CAs by ICD-10-CA categories. These classifications are not confirmed once they are abstracted from the hospital records.
  • Since CCASS is based on hospitalization inpatient data, CAs diagnosed on an ambulatory basis or from outpatient clinics are not captured.
  • Evaluations of the quality of CCASS data indicate that major diagnoses are well captured, but more complex, obscure or less clear-cut diagnoses are less reliably coded.
  • Hospital data can be 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 regions in Ontario and over time, particularly for non-major congenital anomalies.
  • Data are based on geographic maternal/infant residence and not location of hospital of birth or treatment admission. Ontario residents treated outside the province are included in the national dataset when CA data are provided directly from the CCASS system by PHAC; the Ontario health card number is used to extract records by province of residence.
  • Data are available at the census division and census sub-division levels but not by public health unit. Although Ministry of Health codes are available in CIHI data, these are converted to the Standard Geographical Classification (SGC) by the Public Health Agency of Canada and only the SGC is retained by CCASS. In many cases, the public health unit corresponds to a census division or grouping of census divisions with exceptions being in the north. See the Geography in Ontario resource for a listing.
  • Aggregated CA data are available directly from the Maternal and Infant Health Section of the Public Health Agency of Canada. Email to request data. Data are provided in Excel spreadsheets with rates and confidence intervals calculated. The CA categories provided are listed below in Appendix A. The number of cases refers to the number of infants with one or more anomalies. Infants may have multiple anomalies.
  • In 2006, CIHI reprocessed and replaced data from 1993 to 2001. As a result there may be discrepancies between old and more recently acquired data. Use only the latest data.
  • The denominator provided by CCASS to calculate rates of CAs is the total number of live births and stillbirths occurring in hospitals. Once jurisdictions participating in the Canadian Anomalies Surveillance Enhancement initiative begin submitting CA data to CCASS, terminations will also be collected, which will then also be reflected in the denominator.
  • Rates and proportions of CAs from CIHI for counts less than 5 are suppressed; however, rates and proportions from BORN data for counts less than 6 are suppressed.

References and Resources

  1. Public Health Agency of Canada. Canadian Perinatal Health Report, 2008. Available from: Accessed: March 5, 2012.
  2. Paquette D, Lowry RB, Sauve, R. Two to three percent of infants are born with a congenital anomaly, but who's counting? A national survey of congenital anomalies surveillance in Canada. Chronic Diseases in Canada. 2006;27(1):36-38. Available from: Accessed: January 31, 2012.
  3. Rouleau J, Arbuckle TE, Johnson KC, Sherman GJ. Description and Limitations of the Canadian Congenital Anomalies Surveillance System (CCASS). Chronic Diseases in Canada. 1995;16(1):37-42.
  4. Health Canada. Congenital Anomalies in Canada: A Perinatal Health Report, 2002. Available from: Accessed: January 31, 2012.
  5. Lowry, RB. Congenital anomalies surveillance in Canada. Canadian Journal of Public Health. 2008 Nov-Dec; 99(6):483-5.
  Appendix A: Categories of Congenital Anomalies Provided by CCASS


Central nervous system anomalies

Neural tube defects

          Anencephalus & similar anomalies

          Spina bifida


          Microcephalus & brain reduction

          Congenital hydrocephalus

          Other specified & unspecified CNS anom.

Eye anomalies

          Anophthalmos, microphthalmos

          Other eye anomalies

Ear face & neck anomalies

          Anomalies of ear causing impairment

          Other ear anomalies

          Anomalies of face & neck

Congenital heart defects

          Common truncus

          Transposition of great vessels

          Tetralogy of Fallot

          Common ventricle

          Ventricular septal defect

          Atrial septal defect

          Endocardial cushion defects

          Other septal closure defects

          Heart valve anomalies

          Hypoplastic left heart syndrome

          Other heart anomalies

Circulatory system anomalies

          Coarctation of aorta

          Other anomalies of aorta

          Pulmonary artery anomalies

          Other circulatory system anomalies

Respiratory system anomalies

          Nose anomalies

          Lung agenesis & hypoplasia

          Other respiratory system anomalies

Cleft lip and/or palate

          Cleft palate

          Cleft lip

          Cleft palate with cleft lip

Digestive system anomalies

          T-E fistula, esophageal atresia & stenosis

          Other upper alimentary tract anomalies

          Intestinal, anorectal atresia & stenosis

          Other digestive system anomalies

Genital organ anomalies

          Hypospadias, epispadias

          Other genital organ anomalies

Urinary system anomalies

          Renal agenesis & dysgenesis

          Cystic kidney disease

          Other urinary system anomalies

Musculoskeletal anomalies

          Certain musculoskeletal anomalies

          Congenital dislocation of hip


          Polydactyly, syndactyly

          Limb reduction anomalies

          Other, unspecified limb anomalies

          Anomalies of abdominal wall

          Other musculoskeletal anomalies

Anomalies of integument

Down syndrome

Other chromosomal anomalies

          Trisomy 13

          Trisomy 18

          Autosomal syndromes

          Sex chromosome conditions

Other & unspecified anomalies


All anomalies

 Date of last revision: January 3, 2013
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