Can metacarpal cortical area predict the occurrence of hip fracture in women and men over 3 decades of follow-up? Results from the Framingham Osteoporosis Study.

The purpose of this study was to determine if a single measurement of metacarpal cortical area could predict the subsequent risk of hip fracture over a long-term follow-up period. Thirteen hundred eighty-six women and 1014 men (mean age [+/- SD] 61 +/- 8 years) underwent posteroanterior hand radiography between 1966 and 1970 as part of the Framingham Study. Measurements of cortical bone width (external width and medullary width) were made at the midpoint of the second metacarpal with a digital caliper to the nearest 0.1 mm. Hip fracture occurrence was ascertained on all survivors through December 1995. Surprisingly, in women, there was no significant increase in hip fracture according to metacarpal cortical area measurements (per SD decrease) in either age-adjusted (hazard ratio [HR] = 1.13; 95% CI, 0.94-1.35) or multivariate-adjusted models (HR = 1.06; 95% CI, 0.88-1.27). The same results were seen when considering only those women who were > or = 65 years of age at the time of their X-ray or when considering only the first 10 years of follow-up. When the type of hip fracture was considered in women, after adjustment for other risk factors, there appeared to be an association between metacarpal cortical area and intertrochanteric fracture risk (HR = 1.24; 95% CI, 0.91-1.71) but not femoral neck fracture risk (HR = 0.93; 95% CI, 0.71-1.22). In men, the age-adjusted risk of hip fracture was increased modestly per SD decrease in metacarpal cortical area (HR = 1.38; 95% CI, 1.02-1.87), and this remained true after adjustment for potential confounders. In this prospective cohort study with up to 30 years of follow-up, metacarpal cortical area in men predicted hip fracture risk. In women, the only association between metacarpal cortical area and fracture risk was observed for intertrochanteric fractures and was not significant when adjusting for multiple potential confounders. We conclude that this peripheral measure of bone status is not a potent predictor of hip fracture over a long period of follow-up.