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

Marta Benet, Richard Albang, Mariona Pinart, Cynthia Hohmann, Christina G. Tischer, Isabella Annesi-Maesano, Nour Baïz, Carsten Bindslev-Jensen, Karin C. Lødrup Carlsen, Kai Hakon Carlsen, Lourdes Cirugeda, Esben Eller, Maria Pia Fantini, Ulrike Gehring, Beatrix Gerhard, Davide Gori, Eva Hallner, Inger Kull, Jacopo Lenzi, Rosemary McEachanEleonora Minina, Isabelle Momas, Silvia Narduzzi, Emily S. Petherick, Daniela Porta, Fanny Rancière, Marie Standl, Maties Torrent, Alet H. Wijga, John Wright, Manolis Kogevinas, Stefano Guerra, Jordi Sunyer, Thomas Keil, Jean Bousquet, Dieter Maier, Josep M. Anto, Judith Garcia-Aymerich

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)408-417
Number of pages10
JournalAmerican journal of epidemiology
Issue number2
StatePublished - Feb 1 2019


  • allergy
  • asthma
  • birth cohorts
  • data accuracy
  • data harmonization
  • data pooling
  • data sharing

ASJC Scopus subject areas

  • General Medicine


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