Potential Selection Effects when Estimating Associations Between the Infancy Peak or Adiposity Rebound and Later Body Mass Index in Children

Claudia Börnhorst, Alfonso Siani, Michalis Tornaritis, Dénes Molnar, Lauren Lissner, Susann Regber, Lucia Reisch, Alexander Decker, Luis A. Moreno, Wolfgang Ahrens, Iris Pigeot

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Introduction:This study aims to evaluate a potential selection effect caused by exclusion of children with non-identifiable infancy peak (IP) and adiposity rebound (AR) when estimating associations between age and BMI at IP and AR and later weight status.
    Subjects and methods: In 4 744 children with at least 4 repeated measurements of height and weight in the age interval from 0 to 8 years (37 998 measurements) participating in the IDEFICS/I.Family cohort study, fractional polynomial multi-level models were used to derive individual BMI trajectories. Based on these trajectories, age and BMI at IP and AR, BMI values and growth velocities at selected ages as well as the area under the BMI curve were estimated. The BMI growth measures were standardized and related to later BMI z-scores (mean age at outcome assessment: 9.2 years).
    Results: Age and BMI at IP and AR were not identifiable in 5.4 and 7.8% of the children, respectively. These groups of children showed a significantly higher BMI growth during infancy and childhood. In the remaining sample, BMI at IP correlated almost perfectly (r⩾0.99) with BMI at ages 0.5, 1 and 1.5 years whereas BMI at AR correlated perfectly with BMI at ages 4 to 6 (r⩾0.98). In the total study group, BMI values in infancy and childhood were positively associated with later BMI z-scores where associations increased with age. Associations between BMI velocities and later BMI z-scores were largest at ages 5 and 6. Results differed for children with non-identifiable IP and AR demonstrating a selection effect.
    Conclusions: IP and AR may not be estimable in children with higher-than-average BMI growth. Excluding these children from analyses may result in a selection bias that distorts effect estimates. BMI values at age 1 and age 5 might be more appropriate to use as predictors for later weight status instead.
    Introduction:This study aims to evaluate a potential selection effect caused by exclusion of children with non-identifiable infancy peak (IP) and adiposity rebound (AR) when estimating associations between age and BMI at IP and AR and later weight status.
    Subjects and methods: In 4 744 children with at least 4 repeated measurements of height and weight in the age interval from 0 to 8 years (37 998 measurements) participating in the IDEFICS/I.Family cohort study, fractional polynomial multi-level models were used to derive individual BMI trajectories. Based on these trajectories, age and BMI at IP and AR, BMI values and growth velocities at selected ages as well as the area under the BMI curve were estimated. The BMI growth measures were standardized and related to later BMI z-scores (mean age at outcome assessment: 9.2 years).
    Results: Age and BMI at IP and AR were not identifiable in 5.4 and 7.8% of the children, respectively. These groups of children showed a significantly higher BMI growth during infancy and childhood. In the remaining sample, BMI at IP correlated almost perfectly (r⩾0.99) with BMI at ages 0.5, 1 and 1.5 years whereas BMI at AR correlated perfectly with BMI at ages 4 to 6 (r⩾0.98). In the total study group, BMI values in infancy and childhood were positively associated with later BMI z-scores where associations increased with age. Associations between BMI velocities and later BMI z-scores were largest at ages 5 and 6. Results differed for children with non-identifiable IP and AR demonstrating a selection effect.
    Conclusions: IP and AR may not be estimable in children with higher-than-average BMI growth. Excluding these children from analyses may result in a selection bias that distorts effect estimates. BMI values at age 1 and age 5 might be more appropriate to use as predictors for later weight status instead.
    LanguageEnglish
    JournalInternational Journal of Obesity
    Volume41
    Issue number4
    Pages518–526
    ISSN0307-0565
    DOIs
    StatePublished - Apr 2017

    Bibliographical note

    CBS Library does not have access to the material

    Cite this

    Börnhorst, C., Siani, A., Tornaritis, M., Molnar, D., Lissner, L., Regber, S., ... Pigeot, I. (2017). Potential Selection Effects when Estimating Associations Between the Infancy Peak or Adiposity Rebound and Later Body Mass Index in Children. International Journal of Obesity, 41(4), 518–526. DOI: 10.1038/ijo.2016.218
    Börnhorst, Claudia ; Siani, Alfonso ; Tornaritis, Michalis ; Molnar, Dénes ; Lissner, Lauren ; Regber, Susann ; Reisch, Lucia ; Decker, Alexander ; Moreno, Luis A. ; Ahrens, Wolfgang ; Pigeot, Iris. / Potential Selection Effects when Estimating Associations Between the Infancy Peak or Adiposity Rebound and Later Body Mass Index in Children. In: International Journal of Obesity. 2017 ; Vol. 41, No. 4. pp. 518–526
    @article{2156aebc98084c6db78ffe195e2d3bb2,
    title = "Potential Selection Effects when Estimating Associations Between the Infancy Peak or Adiposity Rebound and Later Body Mass Index in Children",
    abstract = "Introduction:This study aims to evaluate a potential selection effect caused by exclusion of children with non-identifiable infancy peak (IP) and adiposity rebound (AR) when estimating associations between age and BMI at IP and AR and later weight status.Subjects and methods: In 4 744 children with at least 4 repeated measurements of height and weight in the age interval from 0 to 8 years (37 998 measurements) participating in the IDEFICS/I.Family cohort study, fractional polynomial multi-level models were used to derive individual BMI trajectories. Based on these trajectories, age and BMI at IP and AR, BMI values and growth velocities at selected ages as well as the area under the BMI curve were estimated. The BMI growth measures were standardized and related to later BMI z-scores (mean age at outcome assessment: 9.2 years).Results: Age and BMI at IP and AR were not identifiable in 5.4 and 7.8{\%} of the children, respectively. These groups of children showed a significantly higher BMI growth during infancy and childhood. In the remaining sample, BMI at IP correlated almost perfectly (r⩾0.99) with BMI at ages 0.5, 1 and 1.5 years whereas BMI at AR correlated perfectly with BMI at ages 4 to 6 (r⩾0.98). In the total study group, BMI values in infancy and childhood were positively associated with later BMI z-scores where associations increased with age. Associations between BMI velocities and later BMI z-scores were largest at ages 5 and 6. Results differed for children with non-identifiable IP and AR demonstrating a selection effect.Conclusions: IP and AR may not be estimable in children with higher-than-average BMI growth. Excluding these children from analyses may result in a selection bias that distorts effect estimates. BMI values at age 1 and age 5 might be more appropriate to use as predictors for later weight status instead.",
    author = "Claudia B{\"o}rnhorst and Alfonso Siani and Michalis Tornaritis and D{\'e}nes Molnar and Lauren Lissner and Susann Regber and Lucia Reisch and Alexander Decker and Moreno, {Luis A.} and Wolfgang Ahrens and Iris Pigeot",
    note = "CBS Library does not have access to the material",
    year = "2017",
    month = "4",
    doi = "10.1038/ijo.2016.218",
    language = "English",
    volume = "41",
    pages = "518–526",
    journal = "International Journal of Obesity",
    issn = "0307-0565",
    publisher = "Nature Publishing Group",
    number = "4",

    }

    Börnhorst, C, Siani, A, Tornaritis, M, Molnar, D, Lissner, L, Regber, S, Reisch, L, Decker, A, Moreno, LA, Ahrens, W & Pigeot, I 2017, 'Potential Selection Effects when Estimating Associations Between the Infancy Peak or Adiposity Rebound and Later Body Mass Index in Children' International Journal of Obesity, vol. 41, no. 4, pp. 518–526. DOI: 10.1038/ijo.2016.218

    Potential Selection Effects when Estimating Associations Between the Infancy Peak or Adiposity Rebound and Later Body Mass Index in Children. / Börnhorst, Claudia; Siani, Alfonso; Tornaritis, Michalis; Molnar, Dénes; Lissner, Lauren; Regber, Susann; Reisch, Lucia; Decker, Alexander; Moreno, Luis A.; Ahrens, Wolfgang; Pigeot, Iris.

    In: International Journal of Obesity, Vol. 41, No. 4, 04.2017, p. 518–526.

    Research output: Contribution to journalJournal articleResearchpeer-review

    TY - JOUR

    T1 - Potential Selection Effects when Estimating Associations Between the Infancy Peak or Adiposity Rebound and Later Body Mass Index in Children

    AU - Börnhorst,Claudia

    AU - Siani,Alfonso

    AU - Tornaritis,Michalis

    AU - Molnar,Dénes

    AU - Lissner,Lauren

    AU - Regber,Susann

    AU - Reisch,Lucia

    AU - Decker,Alexander

    AU - Moreno,Luis A.

    AU - Ahrens,Wolfgang

    AU - Pigeot,Iris

    N1 - CBS Library does not have access to the material

    PY - 2017/4

    Y1 - 2017/4

    N2 - Introduction:This study aims to evaluate a potential selection effect caused by exclusion of children with non-identifiable infancy peak (IP) and adiposity rebound (AR) when estimating associations between age and BMI at IP and AR and later weight status.Subjects and methods: In 4 744 children with at least 4 repeated measurements of height and weight in the age interval from 0 to 8 years (37 998 measurements) participating in the IDEFICS/I.Family cohort study, fractional polynomial multi-level models were used to derive individual BMI trajectories. Based on these trajectories, age and BMI at IP and AR, BMI values and growth velocities at selected ages as well as the area under the BMI curve were estimated. The BMI growth measures were standardized and related to later BMI z-scores (mean age at outcome assessment: 9.2 years).Results: Age and BMI at IP and AR were not identifiable in 5.4 and 7.8% of the children, respectively. These groups of children showed a significantly higher BMI growth during infancy and childhood. In the remaining sample, BMI at IP correlated almost perfectly (r⩾0.99) with BMI at ages 0.5, 1 and 1.5 years whereas BMI at AR correlated perfectly with BMI at ages 4 to 6 (r⩾0.98). In the total study group, BMI values in infancy and childhood were positively associated with later BMI z-scores where associations increased with age. Associations between BMI velocities and later BMI z-scores were largest at ages 5 and 6. Results differed for children with non-identifiable IP and AR demonstrating a selection effect.Conclusions: IP and AR may not be estimable in children with higher-than-average BMI growth. Excluding these children from analyses may result in a selection bias that distorts effect estimates. BMI values at age 1 and age 5 might be more appropriate to use as predictors for later weight status instead.

    AB - Introduction:This study aims to evaluate a potential selection effect caused by exclusion of children with non-identifiable infancy peak (IP) and adiposity rebound (AR) when estimating associations between age and BMI at IP and AR and later weight status.Subjects and methods: In 4 744 children with at least 4 repeated measurements of height and weight in the age interval from 0 to 8 years (37 998 measurements) participating in the IDEFICS/I.Family cohort study, fractional polynomial multi-level models were used to derive individual BMI trajectories. Based on these trajectories, age and BMI at IP and AR, BMI values and growth velocities at selected ages as well as the area under the BMI curve were estimated. The BMI growth measures were standardized and related to later BMI z-scores (mean age at outcome assessment: 9.2 years).Results: Age and BMI at IP and AR were not identifiable in 5.4 and 7.8% of the children, respectively. These groups of children showed a significantly higher BMI growth during infancy and childhood. In the remaining sample, BMI at IP correlated almost perfectly (r⩾0.99) with BMI at ages 0.5, 1 and 1.5 years whereas BMI at AR correlated perfectly with BMI at ages 4 to 6 (r⩾0.98). In the total study group, BMI values in infancy and childhood were positively associated with later BMI z-scores where associations increased with age. Associations between BMI velocities and later BMI z-scores were largest at ages 5 and 6. Results differed for children with non-identifiable IP and AR demonstrating a selection effect.Conclusions: IP and AR may not be estimable in children with higher-than-average BMI growth. Excluding these children from analyses may result in a selection bias that distorts effect estimates. BMI values at age 1 and age 5 might be more appropriate to use as predictors for later weight status instead.

    U2 - 10.1038/ijo.2016.218

    DO - 10.1038/ijo.2016.218

    M3 - Journal article

    VL - 41

    SP - 518

    EP - 526

    JO - International Journal of Obesity

    T2 - International Journal of Obesity

    JF - International Journal of Obesity

    SN - 0307-0565

    IS - 4

    ER -