Potential selection effects when estimating associations between the infancy peak or adiposity rebound and later body mass index in children.
Int J Obes (Lond)
; 41(4): 518-526, 2017 04.
Article
en En
| MEDLINE
| ID: mdl-27899810
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 body mass index (BMI) at IP and AR and later weight status. SUBJECTS ANDMETHODS:
In 4744 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 (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants)/I.Family cohort study, fractional polynomial multilevel 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 4-6 years (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 years. 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 ages 1 and 5 years might be more appropriate to use as predictors for later weight status instead.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Aumento de Peso
/
Índice de Masa Corporal
/
Adiposidad
/
Obesidad Infantil
Tipo de estudio:
Clinical_trials
/
Etiology_studies
/
Incidence_studies
/
Observational_studies
/
Prognostic_studies
/
Risk_factors_studies
Límite:
Child
/
Child, preschool
/
Female
/
Humans
/
Infant
/
Male
/
Newborn
País/Región como asunto:
Europa
Idioma:
En
Revista:
Int J Obes (Lond)
Asunto de la revista:
METABOLISMO
Año:
2017
Tipo del documento:
Article
País de afiliación:
Alemania