, Volume 21, Issue 1, pp 71-79
Date: 05 Jun 2009

Low bone mineral density at femoral neck is a predictor of increased mortality in elderly Japanese women

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Abstract

Summary

This study aimed to determine whether low bone mineral density (BMD) at the femoral neck independently predicts all-cause mortality in elderly Japanese women. A prospective cohort study of 271 women aged 67–89 years was conducted. A Cox proportional hazard model was used to examine independent associations between BMD and total mortality. During a 12-year follow-up period, the mortality risk (as measured by hazard ratio [HR]) was significantly increased in the three categories of baseline BMD (diagnostic criteria of osteoporosis, tertile of BMD, and quartile of BMD). After adjusting for major potential confounding variables for mortality, significantly increased mortality risks were found in subjects with osteoporosis (HR = 2.17, p = 0.032), in subjects in the lowest tertile (HR = 2.57, p = 0.007), and in subjects in the lowest quartile (HR = 3.13, p = 0.014], respectively. Our findings suggest that preventive strategies should be considered to increase and maintain high BMD at the femoral neck in the elderly women not only to prevent hip fractures but also probably to reduce mortality risk.

Introduction

Several longitudinal studies with Caucasian subjects have suggested that osteoporosis is associated with increased mortality. This study aimed to determine whether low bone mineral density (BMD) at the femoral neck independently predicts all-cause mortality in elderly Japanese community-dwelling women.

Method

A prospective cohort study of 271 women aged 67–89 years was conducted. A Cox proportional hazard model was used to examine independent associations between BMD at both the femoral neck and the trochanter and total mortality.

Results

During a 12-year follow-up period, 81 of 271 women (29.9%) died. An independent and significant relationship was found between baseline BMD at the femoral neck and mortality risk. The mortality risk (as measured by HR) was increased by 2.80-fold (95% confidence interval [CI] 1.55–5.06; p < 0.01) in the subjects with osteoporosis or by 2.94-fold (95% CI 1.64–5.26; p < 0.001) in subjects in the lowest tertile or by 3.61-fold (95% CI 1.77–7.41; p < 0.001) in subjects in the lowest quartile of BMD, respectively. After adjusting for major potential confounding factors for mortality such as age, body mass index, blood pressure, blood variables, medical history, alcohol drinking, and smoking status, those in the subjects with osteoporosis (HR = 2.17 [95% CI 1.07–4.41], p = 0.032), in the lowest tertile (HR = 2.57 [95% CI 1.29–5.15], p = 0.007), or in the lowest quartile (HR = 3.13 [95% CI 1.26–7.73], p = 0.014] had a significantly increased risk of mortality. BMD measurement at the trochanter showed similar but weaker results.

Conclusions

Our findings suggest that preventive strategies should be considered to increase and maintain high BMD at the femoral neck in elderly subjects not only to prevent osteoporosis and its associated fractures but also probably to reduce mortality risk.