Fall 2003: Down Syndrome

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Down Syndrome in Saskatchewan

Submitted by Maureen Jackson, Saskatchewan Health

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History of Congenital Anomaly Surveillance in Saskatchewan

Saskatchewan Health routinely conducts surveillance on a number of health conditions, including surveillance on congenital anomalies.

A formalized congenital anomaly surveillance system has not been developed, however, Saskatchewan Health is in discussions with individuals from various sectors across the province in this respect.

In the spring of 2003, we analyzed hospital separations data from 1990-1999 to estimate the prevalence and trends of congenital anomalies in Saskatchewan. The findings will be used to inform the above discussions.

Prevalence of Down Syndrome in Saskatchewan

Methods: Hospital separations data from 1990-1999 were used. This data source has inherent limitations but it can be used to at least estimate trends and burden of illness.

Birth prevalence rate was calculated by dividing the number of Down Syndrome (DS) cases detected in infants by the total number of live births in the province (does not include stillbirths).

Hospitalizations of DS for a particular year were calculated by dividing the sum of all hospital diagnoses of DS by the total provincial population for that year.

Results: Our analysis showed that apart from one high rate recorded in 1990, the DS hospitalization rates over the remaining period (1991-99) have remained stable. Birth prevalence, however, had an overall steady trend. There were no rate differences that we did not expect among the regional health authorities.

Slightly higher rates of DS were recorded for females than for males in the period of study. However, this difference is not statistically significant (95% CI = 0.6-1.17).

In 1999, the Saskatchewan birth prevalence rate of Down Syndrome was 13.5 per 10,000, compared to the national rate of 14.4 per 10,000. Note, however, that Canadian rates include stillbirths and do not include Nova Scotia data. Therefore, Saskatchewan rates cannot be compared without bearing this in mind.

Congenital heart defect (CHD) is a common comorbidity of DS. In Saskatchewan, 17.3% of Down Syndrome children less than one year of age also have a congenital heart defect (CHD).

The following graph illustrates the results of DS prevalence in Saskatchewan for all age groups (not just newborn children). Except for one high value in 1990, the trend has remained fairly stable.

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The following table shows the prevalence of DS in Saskatchewan for children less than one year of age. The overall trend has remained flat.

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Birth Prevalence of Down Syndrome (<1 year) in Saskatchewan, 1990-1999

Year	Number Of Cases	Total Live Births	Prevalence Rate (95% CI) Per 10,000 Live Births
1990	26	15796	16.5 (10.1-22.8)
1991	8	15239	5.2 (1.6- 8.9)
1992	13	15073	8.6 (3.9-13.3)
1993	19	14320	13.3 (7.3-19.2)
1994	20	14167	14.1 (7.9-20.3)
1995	9	13509	6.7 (2.3-11.0)
1996	16	13432	11.9 (6.1-17.7)
1997	10	12849	7.8 (3.0-12.6)
1998	18	12797	14.1 (7.6-20.6)
1999	17	12623	13.5 (7.1-19.9)

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The following graph illustrates the prevalence of DS in children less than one, by sex. The slight increase seen in the prevalence of DS in female children was not statistically significant.

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** This report was developed in cooperation with the Saskatchewan Institute of Applied Science and Technology, as part of a work cooperative initiative. Thanks to Dr. William Osei, Sheena McRae, and Sherri Danylczuk for their assistance. Questions or comments can be directed to Maureen Jackson, chronic disease epidemiologist, SK Health (mjackson@health.gov.sk.ca).

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