Humeral fractures in South-Eastern Australia: epidemiology and risk factors

In this study, we report the epidemiology and risk factors for humeral fractures (proximal humerus and shaft) among men and women residing in south-eastern Australia. Incident fractures during 2006 and 2007 were identified using X-ray reports (Geelong Osteoporosis Study Fracture Grid). Risk factors were identified using data from case-control studies conducted as part of the Geelong Osteoporosis Study. Median age of fracture was lower in males than females for proximal humerus (33.0 vs 71.2 years), but not for humeral shaft (8.9 vs 8.5 years). For females, proximal humerus fractures occurred mainly in the 70-79 and 80+ years age groups, whereas humeral shaft fractures followed a U-shaped pattern. Males showed a U-shaped pattern for both proximal humerus and humeral shaft fractures. Overall age-standardised incidence rates for proximal humerus fractures in males and females were 40.6 (95 % CI 32.7, 48.5) and 73.2 (95 % CI 62.2, 84.1) per 100,000 person years, respectively. For humeral shaft fractures, the age-standardised rate was 69.3 (95 % CI 59.0, 79.6) for males and 61.5 (95 % CI 51.9, 71.0) for females. There was an increase in risk of proximal humerus fractures in men with a lower femoral neck BMD, younger age, prior fracture and higher milk consumption. In pre-menopausal women, increased height and falls were both risk factors for proximal humerus fractures. For post-menopausal women, risk factors associated with proximal humerus fractures included a lower non-milk dairy consumption and sustaining a prior fracture. Humeral shaft fractures in both sexes were sustained mainly in childhood, while proximal humerus fractures were sustained in older adulthood. The overall age-standardised rates of proximal humerus fractures were nearly twice as high in females compared to males, whereas the incidence rates of humeral shaft fractures were similar.