Accuracy of anthropometric measurements and weight status perceptions reported by parents of 4-year-old children.

Objective: To assess the validity of self-reported height and weight by parents of 4-year-old children and subjective weight perception. Design: Descriptive cross-sectional study. Setting: Paediatric population living in the Autonomous Community of Madrid. Participants: Children born in 2008-2009 examined at 47-59 months of age. Data were collected by paediatricians of the Madrid Primary Care Physicians Sentinel Network. Parents reported weight and height data. Prevalence of weight status categories was calculated using WHO and International Obesity Task Force (IOTF) reference criteria. Sensitivity, specificity and positive predictive value (PPV) were estimated. The appraisal of their child's weight perception and parental misperception were assessed. Results: For 2914 children, reported height was underestimated by -1 center dot 38 cm, weight by -0 center dot 25 kg and BMI was overestimated by +0 center dot 41 kg/m(2) on average. The prevalence of obesity estimated with reported data was 2 center dot 7 times higher than that calculated with measured data (16 center dot 2 v. 6 center dot 0 %) according to WHO classification, and 3 center dot 6 times higher with IOTF classification. Sensitivity to identify obesity was 70 center dot 5 %, specificity was 87 center dot 3 % and PPV was 26 center dot 2 % (WHO classification). Half of the parents of pre-schoolers with obesity failed to identify their child's weight status. Parental misperception among children classified as having overweight or obesity reached 93 center dot 0 and 58 center dot 8 %, respectively. Conclusions: Parents underestimated children's height and weight, leading to an overestimation of the prevalence of obesity. Small inaccuracies in reported measures have an important effect for the estimation of population prevalences. Parents' report of child weight status is unreliable. Parental awareness and acknowledgement of child weight status should be improved.