Development of BMI values of German children and their healthcare costs.

The aim of this study is to assess the association between different patterns of Body Mass Index (BMI) development from birth on and later healthcare utilisation and costs in children aged about 10 years based on two birth cohort studies: the GINIplus study (3287 respondents) and the LISAplus study (1762 respondents). Direct costs were estimated using information on healthcare utilisation given by parents in the 10-year follow-up. To meet this aim, we (i) estimate BMI-standard deviation score (BMIZ) trajectories using latent growth mixture models and (ii) examine the correlation between these trajectories and utilisation of healthcare services and resulting costs at the 10-year follow-up. We identified three BMI-trajectories: a normative BMIZ growth class (BMI development almost as in the WHO growth standards), a rapid BMIZ growth up to age 2 years class (with a higher BMI in the first two years of life as proposed by the WHO growth standards) and a persistent rapid BMIZ growth up to age 5 years class (with a higher BMI in the first five years of life as proposed by the WHO growth standards). Annual total direct medical costs of healthcare use are estimated to be on average €368 per child. These costs are doubled, i.e. on average €722 per child, in the group with the most pronounced growth (persistent rapid BMIZ growth up to age 5 years class).