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Ontario Child Health Study follow-up: evaluation of sample loss
M H Boyle1, D R Offord, Y A Racine
1Department of Psychiatry, McMaster University, Hamilton, Ontario, Canada.
Insights
Sample loss in the Ontario Child Health Study did not affect disorder outcome or risk evaluations. However, it did introduce bias in prognosis assessments for child psychopathology.
Area of Science:
- Child and Adolescent Psychiatry
- Longitudinal Cohort Studies
- Mental Health Research
Background:
- The Ontario Child Health Study (OCHS) is a significant longitudinal study tracking child mental health.
- Understanding sample attrition is crucial for validating findings from long-term studies.
- Previous OCHS waves established baseline data on child psychopathology and family risk factors.
Purpose of the Study:
- To analyze the impact of sample loss on a 4-year follow-up of the OCHS cohort.
- To assess how selective attrition affects estimates of child psychopathology outcomes and prognosis.
- To determine if weighting methods can correct for biases introduced by nonparticipation.
Main Methods:
- Analysis of a 4-year follow-up (1987) of the original 1983 OCHS cohort (n=1,617).
- Comparison of located (n=1,172) versus nonparticipant children using baseline psychopathology and family risk data.
- Application of differential weighting to compensate for selective sample loss.
- Comparison of analytical estimates using observed versus weighted follow-up data.
Main Results:
- Nonparticipants at follow-up exhibited higher baseline psychopathology and family risk.
- Sample loss did not significantly bias evaluations of disorder outcomes or risk for disorder.
- Prognostic evaluations, specifically predicting disorder persistence, were affected by a bias toward the null.
Conclusions:
- While sample loss in the OCHS follow-up did not compromise outcome or risk assessments, it did introduce bias in prognostic evaluations.
- Researchers must consider the potential impact of selective attrition on longitudinal mental health study findings, particularly for prognosis.
- Weighting adjustments can mitigate some biases, but careful consideration of analytical focus is essential for accurate interpretation of longitudinal child mental health data.
Abstract:
This article presents an analysis of sample loss in a 4-year follow-up of children aged 4 to 12 who participated in the Ontario Child Health Study in 1983. Of the 1,617 children participating in the original Ontario Child Health Study, 1,172 (72.5%) were located and enlisted at follow-up in 1987. Based on wave-one assessments, nonparticipants at follow-up tended to have higher levels of psychopathology and family risk variables. Respondents were matched with nonparticipants and differentially weighted to compensate for selective loss. In comparing estimates based on actual (observed) and weighted responses in the follow-up sample, it was found that the effects of sample loss depended on the analytical focus. Evaluations of outcome of disorder and risk for disorder were not affected by sample loss. Evaluation of variables that predict persistence of disorder (prognosis) was affected by a bias toward the null.