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This article is part of the supplement: 2nd WAO International Scientific Conference (WISC 2012), Abstracts

Open Access Open Badges Meeting abstract

Health outcomes, education, healthcare delivery and quality – 3048. From uterus to university: Recruitment and retention of a primary prevention birth cohort

Brenda Gerwing1*, Rishma Chooniedass1, Saiful Huq1, Hao Huang2, Anita Kozyrskyj3, Edmond Chan4, Clare Ramsey5, Moira Chan-Yeung6 and Allan Becker1

  • * Corresponding author: Brenda Gerwing

Author Affiliations

1 Pediatrics and Child Health, Section of Allergy, University of Manitoba, Canada

2 University of Manitoba, Winnipeg, MB, Canada

3 Pediatrics, University of Alberta, Edmonton, AB, Canada

4 Pediatrics, University of British Columbia, Vancouver, BC, Canada

5 Internal Medicine, University of Manitoba, Winnipeg, MB, Canada

6 Internal Medicine, University of British Columbia, Vancouver, BC, Canada

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World Allergy Organization Journal 2013, 6(Suppl 1):P218  doi:10.1186/1939-4551-6-S1-P218

The electronic version of this article is the complete one and can be found online at:

Published:23 April 2013

© 2013 Gerwing et al; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


It is important to identify predictors of retention in primary prevention studies as recruitment and retention are critical factors for a successful intervention study.


In 1994, the Canadian Asthma Primary Prevention Study (CAPPS) was established. This high-risk birth cohort has 2 sites, Winnipeg and Vancouver, Canada. Expectant mothers were recruited during the third trimester. Enrollment criteria were a first degree relative with asthma or two first degree relatives with other allergic diseases. Participants were prenatally randomized into control and intervention groups. Intervention measures were introduced before birth and during baby’s first year of life. Follow-up assessments by a Pediatric Allergist included skin prick testing (SPT) to common food and inhalants and pulmonary function testing.


545 participants initially recruited. 266 randomized into control and 279 intervention. From recruitment to first year, 9.5% families (52) discontinued. At age 1, 493 infants were assessed; 52.3% males and 47.7% females, 49.1% control and 50.9% intervention. 76.8% high SES, 22.52% low SES. 9.7% maternal age ≤25 and 90.3% maternal age >25. 17.6 % were diagnosed with asthma at 1 year. 22.1% with +SPT to food. 44.2% were 1stborn. Children were assessed at 2 (n=472, 95.7%) and 7 years (n=380, 77.1%). At 15 years, 326 (66.1%) participants returned; 55.8% males and 44.2% females (p=0.02), 44.5% control and 54.6% intervention (p=0.054). Maternal age >25 (OR=1.73, 95% CI 0.95-3.16, p=0.05), asthma diagnosis (OR=1.53, 95% CI 0.91-2.57, p=0.066), high SES (OR=1.37, 95% CI 0.88-2.11, p=0.1) and +SPT (OR=1.23, 95% CI 0.78-1.95, p=0.22) were all associated with higher rates of return. While 138 participants returned with no sibling(s) at enrollment (OR=0.81, 95% CI 0.56-1.18, p=0.16).


Participants with sibling(s) at birth had no significant difference in retention. Maternal age was the most likely predictor of participant drop out. Female participants, low SES, negative skin prick test to food and no asthma diagnosis at age 1 showed a trend towards drop out. When establishing future asthma and allergy cohorts, specific retention strategies should be considered for groups identified at risk for drop out, especially for younger mothers and female participants.