The association between weight perception and BMI: report and measurement data from the growing up in Ireland Cohort Study of 9-year olds.
The gold standard for categorisation of weight status is clinically measured body mass index (BMI), but this is often not practical in large epidemiological studies.



To determine if a child's weight perception or a mother's perception of a child's weight status is a viable alternative to measured height and weight in determining BMI classification. Secondary outcomes are to determine the influence of a mother's BMI on her ability to categorise the child's BMI and a child's ability to recognise his/her own BMI.



Cross-sectional analysis of the growing up in Ireland cohort study, a nationally representative cohort of 8568 9-year-old children. The variables considered for this analysis are the child's gender, BMI (International Obesity Taskforce grade derived from measured height and weight) and self-perceived weight status, and the mother's weight perception of the child, BMI (derived from measured height and weight) and self-perceived weight status. Cohen's weighted-kappa was used to evaluate the strength of the agreement between pairwise combinations of the BMI variables. Cumulative and adjacent categories logistic regression were used to predict how likely a person rates themselves as under, normal or overweight, based on explanatory variables.



Mothers are more accurate at correctly classifying their child's BMI (κ=0.5; confidence intervals (CI) 0.38-0.51) than the children themselves (κ=0.25; CI 0.23-0.26). Overweight mothers are better raters of their child's BMI (κ=0.51; CI 0.49-0.54), compared with normal (κ=0.44; CI 0.41-0.47) or underweight mothers (κ=0.4; CI 0.22-0.58), regardless of whether the mother's BMI is derived from measured height and weight or self-perceived. The mother's perception of the child's weight status is not an influencing factor on the child's ability to correctly classify him/herself, but the child's self-perceived weight status influences the mother's ability to correctly classify the child.



A mother's BMI classification of her child is a viable alternative to BMI measurement in large epidemiological studies.
Department of Epidemiology and Public Health, University College Cork, Cork, Ireland.|HRB Clinical Research Facility, Mercy University Hospital, Grenville Place, Cork, Ireland.
F
F
Shiely
School of Medicine, University College Cork, Brookfield Health Sciences Complex, Cork, Ireland.
H Y
HY
Ng
Department of Mathematics and Statistics, University of Limerick, Plassey, Limerick, Ireland.
E M
EM
Berkery
School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin 4, Ireland.
C
C
Murrin
School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin 4, Ireland.
C
C
Kelleher
Department of Mathematics and Statistics, University of Limerick, Plassey, Limerick, Ireland.
K
K
Hayes
D000328:Adult; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006306:Health Surveys; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D009035:Mothers / Q000523:psychology*; D063766:Pediatric Obesity / Q000453:epidemiology / Q000523:psychology*; D057566:Self Report; D012959:Socioeconomic Factors
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