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DAPA Measurement Toolkit

 

Harmonisation

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Introduction

This section outlines a case study illustrating some of the harmonisation concepts described on the general data harmonisation page . The example is from the InterConnect consortium, which has used existing data from different study cohorts across the world. Further case studies are available on the corresponding diet (case study 1) and physical activity (case studies 2 and 3) harmonisation pages.


CASE STUDY 4: Algorithm development for harmonisation of percentage body fat at birth target variable for InterConnect exemplar study: Association between physical activity during pregnancy and anthropometry of the offspring.

The InterConnect consortium aimed to investigate associations between physical activity during pregnancy and neonatal anthropometric outcomes using a federated meta-analysis approach. One of the outcomes investigated was percentage body fat, and this was available in three cohorts. Of these, one assessed neonatal body fat by using the air displacement plethysmography (also known as BOD POD, or PEA POD for infants), while skinfold thickness measurements were available for the second cohort and in a subset of the third.

The data from skinfold measurements in cohorts two and three were converted to the common format target variable (percentage body fat, %) using a previously reported algorithm [1]:

  • Percentage body fat = 1.21 (triceps skinfold + subscapular skinfold) - 0.008 (triceps skinfold + subscapular skinfold)2 - 1.7

As there were no data with harmonisation potential in the remaining five cohorts, it was necessary to restrict meta-analysis for this outcome to only the three cohorts described above.

References

  1. Slaughter MH, Lohman TG, Boileau RA, Horswill CA, Stillman RJ, Van Loan MD, et al. Skinfold equations for estimation of body fatness in children and youth. Hum Biol. 1988;60(5):709-23.