Elsevier

The Journal of Pediatrics

Volume 147, Issue 3, September 2005, Pages 312-315
The Journal of Pediatrics

Original Article
Cystic Fibrosis Birth Rates in Canada: A Decreasing Trend since the Onset of Genetic Testing

https://doi.org/10.1016/j.jpeds.2005.06.043Get rights and content

Objective

To estimate cystic fibrosis (CF) birth rates in Canada from 1971 to 2000 and to assess the population impact of genetic testing in families with a history of CF, after identification of the CF transmembrane conductance regulator gene in 1989.

Study design

Age-at-diagnosis data were obtained from the Canadian Cystic Fibrosis Foundation Patient Data Registry and Canadian births for the corresponding years from Canadian Vital Statistics. Estimates of the CF birth rate in each year were based on a nonparametric model that allows the birth rate to vary across the years and adjusts for censoring of currently undiagnosed patients.

Results

The overall CF birth rate from 1971–1987 was 1/2714 with no increasing or decreasing trend. Beginning in 1988, 1 year before identification of the CF transmembrane conductance regulator gene, estimated CF birth rates followed a linear decline to an estimated rate of 1/3608 in 2000. CF birth rates may have stabilized in the last few years, but further decline may occur with implementation of carrier screening in the general population.

Conclusions

These results demonstrate the temporal association of genetic testing and declining CF birth rates in Canada. They may assist in decisions relating to the allocation of resources for prenatal and neonatal CF screening programs.

Section snippets

Data

A table of age-at-diagnosis by birth year for patients born and diagnosed between 1971 and 2000 was obtained from the CCFF Patient Data Registry. The registry collects data annually from 38 specialized CF clinics throughout Canada. Because of the single-payer government health care system in Canada, virtually all patients diagnosed with CF are seen in these specialized clinics. Canadian births were obtained from the federal demographics database, Canadian Vital Statistics, for the corresponding

Results

Between 1971 and 1987, there were no significant trends in the estimates of the CF birth rates obtained from the nonparametric Poisson model (Figure). Although estimated annual rates fluctuated considerably through the 1970s and 1980s, the overall CF birth rate obtained from the segmented linear Poisson model was 1/2714, with no increasing or decreasing trend. A decline in CF birth rates was observed from 1988 to 2000, yielding an estimated birth rate for year 2000 of 1/3608, a 25% decrease

Discussion

Determining an accurate and unbiased estimate of CF birth rates has been an issue ever since registries and large population surveys of the disorder became available. Gregg et al14 used data from the Wisconsin CF newborn screening program for the period of April 1985 to June 1991 to estimate the birth prevalence rate of CF. Newborns with serum immunoreactive trypsinogen levels ≥180 ng/mL on screening were then being diagnosed at 6 weeks of age by sweat chloride determinations after pilocarpine

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  • Cited by (0)

    Supported by CCFF, CIHR, NSERC, Genome Canada.

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