Improved femoral neck BMD in older Finnish women between 2002 and 2010

The number of hip fractures among Finns over 50-years of age rose constantly between 1970 and 1997, but since then, there has been a nationwide decline in incidence of hip fractures. One possible explanation, although not the only one, for the declining fracture rates, could be improved bone mineral density (BMD). The aim of this study was to evaluate differences in femoral neck BMD between older Finnish women born about a decade apart.

We compared the baseline data of two population-based samples of home-dwelling 70-80-year-old women who were initially recruited in exercise intervention studies (N=216 in Cohort1, and N=389 in Cohort 2). Femoral neck BMD was measured with DXA. Between-cohort differences were evaluated with analysis of covariance using age, height, weight, and use of hormone therapy as covariates.

The later-born Cohort 2 was somewhat older and taller than Cohort 1. Adjusted mean difference (95% CI) in femoral neck BMD between the cohorts was 0.043g/cm(2) (0.023-0.064) corresponding the mean difference of 0.36 (0.19-0.53) in T-score in favor of Cohort 2.

Despite several factors that basically could have indicated lower mean BMD in Cohort 2, the finding was the opposite. This suggests that the mean femoral neck BMD has increased substantially among older Finnish women within a decade, but primary reason for this improvement remains unclear, but improved social and economic resources may have at least partly accounted for this favorable phenomenon.