London School of Hygiene & Tropical Medicine

Parents of obese children may not be able to recognise that their child is overweight unless they are at very extreme levels of obesity, according to research led by the London School of Hygiene & Tropical Medicine and UCL Institute of Child Health, research partner of Great Ormond Street Hospital.

The work, which is published in the British Journal of General Practice, finds that parents are additionally more likely to underestimate their child's weight if they are Black or south Asian (v white), from more deprived backgrounds or if their offspring is male. The identification of gaps between parental perceptions and official guidelines, and variations seen in different demographics of the population, may help us evaluate how effective public health interventions for obesity in children are going to be in different groups of the population.

Childhood obesity has increased in the UK in recent decades and with obese children being at greater risk of premature mortality and disease in adulthood, interventions to tackle obesity have been put in place by the government. But, research has suggested that many parents can't identify when their child is overweight leading to questions about the effectiveness of current public health interventions which aim to address obesity in the home.

The research team set out to look at the scale of this problem further and identify socioeconomic factors that may predict parental under or overestimation of their child's weight. Questionnaire responses were collected from parents of 2976 children in five primary care trusts taking part in the National Child Measurement Programme (NCMP) ; Redbridge, Islington, West Essex, Bath and North East Somerset and Sandwell.

The researchers discovered that 31% of parents (915) underestimated where their child's BMI sat on government obesity scales - which classify children as very overweight (or obese), overweight, healthy weight, or underweight. Highlighting this discrepancy, they found that only four parents described their child as being very overweight despite 369 children being officially identified as very overweight according to the BMI cut-off. According to official guidelines, children are classified as overweight at the 85^th centile and very overweight (or obese) at the 95^th centile. The team estimated that for a child with a BMI at the 98^th centile there was an 80% chance that the parent would classify their child as healthy weight but recognised that parents became more likely to classify their child as overweight when the child had a BMI above the 99.7^th centile.

Senior author Dr Sanjay Kinra, Reader in Clinical Epidemiology at the London School of Hygiene & Tropical Medicine and co-lead investigator of the PROMISE trial, said: "If parents are unable to accurately classify their own child's weight, they may not be willing or motivated to enact the changes to the child's environment that promote healthy weight maintenance."

Co-author Professor Russell Viner, academic paediatrician at the UCL institute of Child Health and PROMISE co-lead investigator said: "Measures that decrease the gap between parental perceptions of child weight status and obesity scales used by medical professionals may now be needed in order to help parents better understand the health risks associated with overweight and increase uptake of healthier lifestyles."

The study was funded by the National Institute for Health Research and forms part of the PROMISE study, a five part* project led by UCL Institute of Child Health and the London School of Hygiene & Tropical Medicine that aims to improve the assessment and treatment of childhood obesity through research.

Publication

James Black, MinHae Park, John Gregson, Catherine Falconer, Billy White, Anthony Kessel, Sonia Saxena, Russell Viner , Sanjay Kinra. Child obesity cut-offs as derived from parental perceptions: cross-sectional questionnaire. Br J Gen Pract 2015. DOI: 10.3399/bjgp15X684385

*PROMISE (Paediatric Research In Obesity Multi-Modal Intervention And Service Evaluation consists of five studies :-

• Study A: Impact of the National Child Measurement Programme (NCMP) - led by London School of Hygiene & Tropical Medicine
• Study B: Improving childhood obesity management - led by London School of Hygiene & Tropical Medicine
• Study C: Healthy Eating and Lifestyle programme (HELP) - led by UCL ICH
• Study D: Effectiveness of anti-obesity drug - led by UCL
• Study E: Evaluation of an adolescent bariatric surgery programme - led by UCLH