Does the use of color coding facilitate parents' understanding of body mass index curves?

Background: In France, national guidelines recommend early detection and management of overweight and obesity in children, with multi-year systematic generation of children's body mass index (BMI) curves in primary care. It is important for the parents to understand the BMI curves displayed in the child's health notebook and to become involved in the care with health professionals.

Objective: The aim of the current study was to compare parents' understanding of a BMI curve displayed using color coding versus their understanding of the same curve displayed without color coding.

Methods: An observational, cross-sectional, comparative study was performed between February 1, 2021 and November 15, 2021. Adult parents with at least one child attending primary school were included. Two questionnaires testing parents' understanding were completed: one showing BMI curves without color coding (five questions) and one showing BMI curve with color coding (five questions). The primary endpoint was the proportion of parents achieving fully correct answers. Comparisons of endpoints between the color-coded and non-color-coded curve were performed using the McNemar test. Factors associated with the primary endpoint were investigated by mixed logistic regression models with the subject as a random effect.

Results: The 109 participants (45.4% response rate) had an average age of 39.4 ± 6.6 years; 81.7% were women. A total of 214 complete questionnaires were compared: The proportion of participants with fully correct responses was significantly higher using the BMI curve with color coding compared to the curve without color coding (86.0% vs. 54.2%, p<0.0001). In multivariate analysis, the use of color coding was significantly associated with a higher likelihood of achieving fully correct responses (odds ratio: 5.9, 95% CI: 3.0-11.2, p<0.0001).

Conclusion: The use of color coding improved parents' understanding of BMI curves. Further research should explore equally the benefits and risks associated with weight loss and mental health when using a colored BMI curve for the detection and management of overweight and obese children.