Childhood Obesity Associated With Increased Fracture Risk

Daniel Prieto-Alhambra, MD, PhD

Pre-school children who had obesity or were overweight may be at an increased risk of bone fractures during childhood compared to normal weight children of their age, according to the findings of a new study.

Daniel Prieto-Alhambra, MD, PhD, and colleagues collected data from primary care centers to determine if having an overweight or obese range body mass index (BMI) at the beginning of school was associated with increased fracture incidence during childhood.

The team found a strong correlation between pre-school overweight and obesity and the risk of fracture during childhood.

Prieto-Alhambra, of the University of Oxford in the United Kingdom, included 466,997 children. The data were collected anonymized primary care electronic health records (EHRs) from the Information System for Research in Primary Care (SIDIAP). The database covered >74% of the total Catalonia population and contained information from 296 primary care centers and 853 primary care pediatricians.

Children were assessed at their school starting at 4 years old by a pediatrician or pediatric nurse. To be included, participants had >1 valid height and weight measurement recorded within the recruitment period. The team used the height and weight to calculate BMI.

The participants were followed up from the date of the BMI measurement until they were 15 years old, migrated out of the SIDIAP region, died, or the study ended.

The main exposure was BMI category (underweight, normal weight, overweight, and obesity) at 4 years old. Fracture incident was determined using validated lists of ICD-10 codes. The codes were validated within the SIDIAP database before the study with a positive predictive value of 80.5%.

The investigators identified 466,997 children with height and weight measurements taken at a mean 49.1 months. The children were followed for a median of 4.9 (IQR, 2.5-7.61) years.

Of the children included, 5.7% had an overweight BMI and 2% had an obese BMI. There were similar numbers of males and females in the overweight BMI category (47% female) but slightly more boys and children from more deprived areas in the obese category.

The cumulative fracture incidence in childhood from ages 4-14 years old was 10.19% (95% CI, 9.96-10.43). After stratifying by sex, cumulative incidence was 8.24% (95% CI, 7.99-8.49) in girls and 12.05% (95% CI, 11.66-12.44) in boys.

Upper limb fractures were most commonly affected in both sexes, followed by lower limb. Axial fractures were rare in childhood.

Overall, incidence of fracture during childhood was 9.20% (95% CI, 3.79-14.61) for underweight children, 10.06% (9.82-10.29) for normal weight, 11.28 (10.22-12.35) for children with an overweight BMI, and 13.05% (10.69-15.41) for children with obesity.

Having overweight or obese BMI was linked to an excess risk of lower limb fracture (adjusted HR, 1.42; 95% CI, 1.26-1.59; aHR, 1.74; 1.46 to 2.06, respectively) and upper limb fracture (aHR, 1.1; 1.03-1.17; aHR, 1.19; 1.07-1.31).

Being overweight or obese was linked with 42% and 74% higher risks of lower limb fractures compared with normal weight and a 10% and 19% higher risk of upper limb fractures.

Future research could help investigators understand the mechanisms underlying the correlation between weight and fracture risk.

The study, “Preschool Obesity Is Associated With an Increased Risk of Childhood Fracture: A Longitudinal Cohort Study of 466,997 Children and Up to 11 Years of Follow-up in Catalonia, Spain,” was published online in the Journal of Bone and Mineral Research.