In older adults, a low baseline bone mineral density score and a rapid bone loss over 7 years independently conferred increased mortality risk, with a stronger association observed in men vs. women, according to findings published in Bone.
Hak C. Jang
“The skeleton plays diverse roles via crosstalk between organs about various functions, such as energy metabolism and maintenance of lean mass,” Hak C. Jang, MD, PhD, professor in the department of internal medicine at Seoul National University Bundang Hospital, South Korea, and colleagues wrote in the study background. “Therefore, it is conceivable that low baseline BMD or rapid loss of BMD may indicate negative influences on health status beyond the potential for fracture events.”
Jang and colleagues analyzed data from 339 adults aged at least 65 years (167 women) participating in the Korean Longitudinal Study on Health and Aging, a community-based, prospective study on health, aging and common geriatric diseases. Baseline evaluations were performed between 2005 and 2006. Researchers assessed DXA measurements at the lumbar spine, femoral neck and total hip, as well as whole-body composition. Low bone mass was defined as a T-score of less than –1 and greater than –2.5. Rapid bone loss was defined as an annualized bone loss rate of at least 1 standard deviation (SD) of the sex-specific loss rate at each skeletal site. Follow-up BMD evaluations were conducted between 2010 and 2011. Researchers collected mortality data from the National Death Registry.
During a mean follow-up for the cohort of 7.3 years, 74 men and 50 women died. Researchers observed that BMD and T-scores were lower and the prevalence of osteoporosis was higher in participants who died vs. survivors among both men and women. There were no between-group differences for fracture rates.
Baseline BMD , mortality
Researchers stratified participants according to three BMD groups, including normal, low bone mass and osteoporosis, and calculated the relative risk for mortality during follow-up.
Osteoporosis at all skeletal sites was associated with increased mortality risk for men and women; however, the associations were stronger for BMD at the femoral neck and total hip vs. the lumbar spine, according to researchers.
In unadjusted analyses, researchers found that osteoporosis at the femoral neck was the strongest predictor of increased mortality risk for both men (HR = 6.32; 95% CI, 2.38-16.77) and women (HR = 17.07; 95% CI, 2.24-130.4) when compared with sex-matched participants in the normal BMD group.
After adjustment for age, BMI, osteoporosis treatment and other factors, results persisted for men only, according to researchers; however, among women, each 1-SD increase in BMD at the lumbar spine and total hip was associated with increased mortality, with HRs of 1.4 (95% CI, 1.02-1.94) and 1.73 (95% CI, 1.09-2.75), respectively.
At follow-up, annual mean percent BMD changes for men were –0.23% for the lumbar spine, –0.28% at the femoral neck and –0.64% at the total hip. Among women, annual mean percent BMD changes were 0.17% for the lumbar spine, –0.74% at the femoral neck and –0.91% at the total hip.
For men, a decline in BMD at all skeletal sites was associated with increased mortality risk after adjustment for covariates; however, for women, researchers observed an association at only the femoral neck site.
“Both lower baseline BMD and a faster decline in BMD were associated with excess [mortality] in a community-dwelling elderly population, especially in men,” the researchers wrote. “The exact mechanisms underlying this link between low bone mass and mortality are not clear, but this study suggests that lower bone mass and faster bone loss may be markers of poorer health, which may contribute to the risk of mortality. Whether therapeutic interventions to reverse diminished bone mass or prevent greater loss are effective remains to be elucidated.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.