Evaluating the accuracy of a geographic closed-ended approach to ethnicity measurement, a practical alternative

Purpose: Measuring ethnicity accurately is important for identifying ethnicity variations in disease risk. We evaluated the degree of agreement and accuracy of maternal ethnicity measured using the new standardized closed-ended geographically based ethnicity question and geographic reclassification of open-ended ethnicity questions from the Canadian census.  Methods: A prospectively designed study of respondent agreement of mothers of healthy children age 1-5 years recruited through the TARGet Kids! practice based research network. For the primary analysis, the degree of agreement between geographic reclassification of the Canadian census maternal ethnicity variables and the new geographically based closed-ended maternal ethnicity variable completed by the same respondent was evaluated using a kappa analysis.  Results: 862 mothers who completed both measures of ethnicity were included in the analysis. The kappa agreement statistic for the two definitions of maternal ethnicity was 0.87 (95% CI: 0.84-0.90) indicating good agreement. Overall accuracy of the measurement was 93%. Sensitivity and specificity ranged from 83-100% and 96-100% respectively.  Conclusion: The new standardized closed-ended geographically based ethnicity question represents a practical alternative to widely used open-ended ethnicity questions. It may reduce risk of misinterpretation of ethnicity by respondents, simplify analysis and improve the accuracy of ethnicity measurement.</p

Non-Western immigrant children have lower 25-hydroxyvitamin D than children from Western families

Objective: To determine if children aged 1-6 years from non-Western immigrant families have lower serum 25-hydroxyvitamin D (25(OH)D) levels than children from Western-born families and examine which factors influence this relationship. Design: Cross-sectional study. Setting: Toronto, Canada. Subjects: Healthy children (n 1540) recruited through the TARGet Kids! practice-based research network. Serum 25(OH)D concentrations of non-Western immigrants were compared with those of children from Western-born families. Children from non-Western immigrant families were defined as those born, or their parents were born, outside a Western country. Univariate and multiple linear regression analyses were used to identify factors which might influence this relationship. Results: Median age was 36 months, 51 % were male, 86 % had 'light' skin pigmentation, 55 % took vitamin D supplements, mean cow's milk intake was 1·8 cups/d and 27 % were non-Western immigrants. Median serum 25(OH)D concentration was 83 nmol/l, with 5 % having 25(OH)D Conclusions: There is an association between non-Western immigration and lower 25(OH)D in early childhood. This difference appears related to known vitamin D determinants, primarily vitamin D supplementation, representing opportunities for intervention.</p