Background:
Risk factors for age-related bone loss have not been well documented. The present study examined the relationship between femoral neck bone loss and lifestyle factors in elderly women.
Methods:
We analysed the data from the Study of Osteoporosis Fractures that included 9704 Caucasian women aged 65 years and above. Bone mineral density (BMD) at the femoral neck was measured by DXA (Hologic QDR 1000 and QDR 2000) at baseline and subsequent visits. We limited the analysis to those with at least 3 BMD measurements (n=4903). For each woman, the rate of change in BMD was estimated by the linear regression model. Smoking was classified as "never smoking", "ex-smoking", and "current smoking". Alcohol use was classified as "drinking" vs "non-drinking". Physical activity was quantified as total calories burned by activity and walking per week. Dietary calcium intake (mg/week) and dietary protein intake (mg/week) were ascertained based on self-reports.
Results:
The annual rate of loss in FNBMD progressively increased with age: −0.8±1.7, −1.1±2.4, and −1.7±2.7 (mean±SD) among those aged 65–69, 70–79, and ≥80 years, respectively (p<0.001). Women smokers suffered a greater rate of bone loss (-1.3±1.9% per year) than ex-smokers/non-smokers (-0.9±2.2% per year, p=0.002). However, alcohol users were associated with a lower bone loss (-0.9±2.1% per year) than abstainers (-1.0±1.9% per year; p=0.024). The calories burned from activity and walking was adversely associated with a higher rate of bone loss after adjustment for age (p<0.001). Greater dietary calcium intakes were associated with a lower rate of bone femoral neck bone loss (p=0.01). However, there was no statistically significant association between dietary protein intakes and bone loss. Collectively, these lifestyle factors explained approximately 2% of the variance in bone loss.
Conclusion:
These data suggest that post-menopausal bone loss is increased with advancing age, and that the loss can be reduced by modifying lifestyle factors.