Overweight and obesity in preschool aged children and risk of mental health service utilization

Objective To determine if overweight or obesity in preschool-age children is associated with mental health service utilization in later childhood. Subjects Overall, 10,522 children 2 to <5 years, with no previous history of mental health service utilization, were identified from primary care electronic medical records (EMRs) across Ontario, Canada. Methods This was a retrospective longitudinal cohort study. Height and weight data were extracted and body mass index zscores (zBMI) were calculated using the World Health Organization Growth Standards. Mental health service utilization, between ages 5 and <19, was defined using administrative billing codes for mental health outpatient visits, emergency department visits, and hospitalizations. A multivariable Cox proportional hazards model was performed. Results In total, 74.9% of children were healthy weight (zBMI between -2 <= 1) and 18.8% of children were at risk of overweight (zBMI between 1 and <= 2), 4.9% were overweight (zBMI > 2 and <= 3) and 1.5% had obesity (zBMI > 3). The median follow-up time was 2.2 years (IQR 1.0-4.2). The overall incidence rate of mental health service use was 44.5 events per 1000 person-years. The hazard ratio for girls with obesity was 2.73 (95% CI 1.62-4.60; p < 0.001) compared to girls with healthy weight. Compared to boys with healthy weight, boys 'at risk of overweight' and overweight were 1.22 (95% CI 1.03-1.44; p = 0.02) and 1.43 (95% CI 1.09-1.87; p = 0.01) times at higher risk of an incident mental health visit. Conclusion Our study shows an association between weight status in preschool school aged children and higher incidence of mental health service use in later childhood. This relationship was strongest in girls. Future research is needed to understand this relationship by mental health diagnosis, sex, and age.