Healthcare costs of childhood overweight and obesity in Chile: evidence from an analysis of linked administrative records.

Background: Childhood overweight and obesity are highly prevalent in Chile, affecting over 50% of children under the age of 12, yet evidence on the healthcare costs associated with them remains limited. In this study, we quantify the association between high body mass index (BMI)-for-age and annual health expenditures among school-aged children using linked national administrative data. Methods: We linked anthropometric measurements from a national school-based surveillance system with health expenditure records from the public and private insurance systems. The sample included children in pre-kindergarten, kindergarten, first, and fifth grade. We estimated average annual expenditures by BMI-for-age categories and used generalised linear models to assess associations between nutritional status and total annual medical spending. Models were sequentially adjusted for demographic, socioeconomic, perinatal, and municipal variables, with additional specifications incorporating municipality fixed effects. Results: Among the 652,297 analysed children, those with a high BMI-for-age had higher mean annual expenditures than those with a normal BMI. In adjusted models, high BMI-for-age was associated with approximately 4.2-4.5% higher spending across specifications. When analysed separately, overweight was associated with approximately 2.5% higher spending and obesity with 6.1-6.6%. Expenditures were lower for girls than for boys, and younger age and lower maternal education were associated with higher expenditures. Conclusions: High BMI-for-age is consistently associated with higher medical expenditures among Chilean children, with costs rising from overweight to obesity. The findings indicate that expenditure differences are already present in early childhood and highlight the need for early prevention strategies. Although modest per child, these differences may add up to substantial aggregate costs, given that more than half of children have overweight or obesity.