Objectives

To evaluate the relationship between life-space (the extent, frequency, and independence of an individual's movement) and mortality in older men.

Design

Prospective cohort study.

Setting

Six U.S. clinical sites.

Participants

Men aged 71 to 98 followed from 2007 to 2011 (N = 3,892).

Measurements

Life-space during the past month was assessed as 0 (daily restriction to one's bedroom) to 120 (daily trips outside one's town without assistance) and categorized into 20-point intervals. The primary outcome was noncancer mortality, and secondary outcomes were all-cause, cardiovascular, cancer, and noncardiovascular noncancer mortality.

Results

Over 2.7 years (2007-2011), 373 (9.6%) men died, 230 from noncancer causes. Unadjusted risk of noncancer mortality was 41.2% in men with the lowest level of life-space (0-20 points, n = 34) and 2.4% in men with the highest level of life-space (101-120 points, n = 868), a 17 times difference. In multivariable-adjusted models, there was a strong linear trend between decreasing life-space and increasing risk of noncancer mortality (P = .005). Risk of noncancer mortality was 3.8 times higher (95% confidence interval (CI)=1.3,11.5) in men with the lowest life-space than in those with the highest life-space. Risk of noncancer mortality was 1.3 times higher (95% CI=1.1-1.5) for each standard-deviation (24 point) decrease in life-space. Risk of noncancer mortality was 1.5 times higher (95% CI=1.0-2.3) in men who did not travel beyond their neighborhood without assistance (n = 471). Results were similar for all-cause mortality and did not change after control for chronic disease burden.

Conclusion

Life-space predicted a variety of mortality endpoints in older men; scores of 40 or less were associated with mortality independent of other risk factors.

Elevated vertebral bone marrow fat (BMF) among individuals with osteoporosis has been established in histomorphometric studies. Several studies have found a negative correlation between BMF and bone mineral density (BMD) at the spine in men and women across different age groups. Animal studies have also observed bone loss with increased BMF in mice with induced diabetes. Our study objective was to test the hypothesis that the association between BMF and BMD varies by diabetic status. We performed a cross-sectional study of 156 men aged 74-96years from the Osteoporotic Fractures in Men study at the Pittsburgh clinical site. All men had spine BMF scans using proton magnetic resonance spectroscopy and spine and hip BMD scans by dual-energy X-ray absorptiometry. BMF was expressed as lipid to "lipid+water" ratio (%). Men were considered diabetic if they self-reported a physician diagnosis of diabetes, diabetes medication or had a fasting glucose ≥126mg/dl. Men with diabetes (n=38) had a significantly higher spine BMF (58.9 vs. 54.6%, p=0.0035), spine BMD (1.20 vs. 1.10g/cm², P=0.007) and total hip BMD (1.00 vs. 0.94g/cm², p=0.04) than those without, while no differences were observed for body weight, body mass index or waist circumference. Pearson correlation tests showed no significant correlation of spine BMF with age or BMD in non-diabetics. Significant inverse correlations were observed between BMF and BMD (-0.30 for femoral neck and -0.39 for total hip) among diabetic men. In conclusion, men with diabetes had a higher BMF compared to non-diabetic men. The correlation between BMF and BMD differed by diabetes status. Further investigation of the association of diabetes with BMF and BMD may provide a better understanding of the high fracture rates among individuals with diabetes despite their higher BMD.