OBJECTIVES

Low body mass index (BMI) is an established risk factor for several types of fracture in postmenopausal women. The relation has not been well studied for fracture of the radius.

METHODS

Female patients aged ≥50 years with a record of BMI were identified in TriNetX ‘Analytics’ (TriNetX, Cambridge, MA), a live electronic medical record database of >50M patients, mostly from the US (analysis 24-May-2019). Incident radius fractures occurring after the first recorded BMI were identified with ICD-10 codes (S52.X). The joint association of age (50-80+ years in 5-year bands) and BMI (15-45+ kg/m² in 5-kg/m² bands) with radius fractures was assessed by calculating risk ratios (RR), with women aged 50-<55 years and a BMI of 20-<25 kg/m² being the reference group.

RESULTS

Incidence of radius fractures was 485/51,609 (9.4/1000 population) in the reference group aged 50-<55 years with BMI 20-<25 kg/m², and ranged from 6.4/1000 at 50-<55 years and 40-<45 kg/m² to 29/1000 at ≥80 years and 15-<20 kg/m². Risk increased with age, with RR of 2.57 (95% CI 2.32 to 2.85) in women aged ≥80 years with a BMI of 20-<25 kg/m². Incidence was inversely related with BMI up to 45+ kg/m² for ages 50-<55 years and up to 40 kg/m² for all other age categories. For instance, in women aged 55-<55 years, compared to BMIs between 20-<25 kg/m², the RR (95% CI) was 1.31 (1.06 to 1.63) at BMIs of 15-<20 kg/m², then decreased to 0.68 (0.49 to 0.95) at BMIs of 40-<45 kg/m², and then went up to 1.00 (0.83 to 1.19) at BMIs of 45-60 kg/m². Similar trends were present in other age groups.

CONCLUSIONS

The incidence of fractures of the radius increased with age and was inversely related with BMI, with exception of the group with highest BMI in which risk was elevated.