Integrating Clinical and Epidemiologic Data on Allergic Diseases Across Birth Cohorts: A Harmonization Study in the Mechanisms of the Development of Allergy Project.

The numbers of international collaborations among birth cohort studies designed to better understand asthma and allergies have increased in the last several years. However, differences in definitions and methods preclude direct pooling of original data on individual participants. As part of the Mechanisms of the Development of Allergy (MeDALL) Project, we harmonized data from 14 birth cohort studies (each with 3-20 follow-up periods) carried out in 9 European countries during 1990-1998 or 2003-2009. The harmonization process followed 6 steps: 1) organization of the harmonization panel; 2) identification of variables relevant to MeDALL objectives (candidate variables); 3) proposal of a definition for each candidate variable (reference definition); 4) assessment of the compatibility of each cohort variable with its reference definition (inferential equivalence) and classification of this inferential equivalence as complete, partial, or impossible; 5) convocation of a workshop to agree on the reference definitions and classifications of inferential equivalence; and 6) preparation and delivery of data through a knowledge management portal. We agreed on 137 reference definitions. The inferential equivalence of 3,551 cohort variables to their corresponding reference definitions was classified as complete, partial, and impossible for 70%, 15%, and 15% of the variables, respectively. A harmonized database was delivered to MeDALL investigators. In asthma and allergy birth cohorts, the harmonization of data for pooled analyses is feasible, and high inferential comparability may be achieved. The MeDALL harmonization approach can be used in other collaborative projects.

Maternal occupation during pregnancy, birth weight, and length of gestation: combined analysis of 13 European birth cohorts.

OBJECTIVES: We assessed whether maternal employment during pregnancy - overall and in selected occupational sectors - is associated with birth weight, small for gestational age (SGA), term low birth weight (LBW), length of gestation, and preterm delivery in a population-based birth cohort design. METHODS: We used data from >200 000 mother-child pairs enrolled in 13 European birth cohorts and compared employed versus non-employed women. Among employees, we defined groups of occupations representing the main sectors of employment for women where potential reproductive hazards are considered to be present. The comparison group comprised all other employed women not included in the occupational sector being assessed. We performed meta-analyses of cohort-specific estimates and explored heterogeneity. RESULTS: Employees had a lower risk of preterm delivery than non-employees [adjusted odds ratio (OR adj) 0.86, 95% confidence interval (95% CI) 0.81-0.91]. Working in most of the occupational sectors studied was not associated with adverse birth outcomes. Being employed as a nurse was associated with lower risk SGA infants (OR adj0.91, 95% CI 0.84-0.99) whereas food industry workers had an increased risk of preterm delivery (OR adj1.50, 95% CI 1.12-2.02). There was little evidence for heterogeneity between cohorts. CONCLUSIONS: This study suggests that, overall, employment during pregnancy is associated with a reduction in the risk of preterm birth and that work in certain occupations may affect pregnancy outcomes. This exploratory study provides an important platform on which to base further prospective studies focused on the potential consequences of maternal occupational exposures during pregnancy on child development.

Parents and school children reported symptoms and treatment of allergic disease differently.

OBJECTIVE: To examine the difference between children and their parents in reporting symptoms and treatment of allergic diseases within a longitudinal birth cohort. STUDY DESIGN AND SETTING: Information on symptoms and treatment of asthma, rhinitis, and eczema was obtained by questionnaire from 2,744 children (mean age: 12 years) and their parents. Differences between the responses were computed, and agreement assessed both absolutely and with kappa coefficient. RESULTS: On 12 of the 15 questions, children's and parents' reports differed significantly. Asthma-related issues appeared significantly more prevalent in the children's reports, although kappa values were fair to very good. For symptoms of allergic rhinitis, the prevalence pattern varied, and kappa values were moderate to good. Parents reported a higher prevalence of eczema-related issues, but the children reported a significantly higher prevalence of eczema itself. Kappa values ranged from moderate to good. CONCLUSION: Although reports of allergic symptoms and treatment by 12-year-old children and their parents were in moderate-to-good agreement, children reported more symptoms than their parents. Symptoms of allergic disease should be reported by children themselves, from the age of 11 years, whereas questions of prescribed pharmacological treatment could be answered either by the children or their parents.

Adherence to national guidelines for children with asthma at primary health centres in Sweden: potential for improvement.

BACKGROUND: Although asthma is the most common chronic paediatric disease in Western Europe, the extent of adherence to guidelines for primary care management of paediatric asthma remains unclear. AIMS: To evaluate adherence to national guidelines for primary care management of children with asthma. METHODS: This survey involved 18 primary healthcare centres in Stockholm, Sweden. The medical records of 647 children aged 6 months to 16 years with a diagnosis of asthma, obstructive bronchitis, or cough were selected and scrutinised. 223 children with obstructive bronchitis or cough not fulfilling the evidence-based criteria for asthma were excluded, yielding a total of 424 subjects. Documentation of the most important indicators of quality as stipulated in national guidelines (i.e., tobacco smoke, spirometry, pharmacological treatment, patient education, and demonstration of inhalation technique) was examined. RESULTS: Only 22% (n=49) of the children 6 years of age or older had ever undergone a spirometry test, but the frequency was greater when patients had access to an asthma nurse (p=0.003). Although 58% (n=246) of the total study population were treated with inhaled steroids, documented patient education and demonstration of inhalation technique was present in 14% (n=59). Exposure to tobacco smoke was documented in 14% (n=58). CONCLUSIONS: This study reveals a substantial gap between the actual care provided for paediatric asthma and the recommendations formulated in national guidelines.