Men at least 65 years of age were more likely to fall if their total and bioavailable (Bio) levels of testosterone (T) were low, according to the results of a study published in the Journal of Bone and Mineral Research. However, levels of estradiol (E2) and sex hormone-binding globulin did not affect the rate of falls.
“The association between both total T and BioT and falls was at least partly independent of physical performance and lean mass and remained relatively unchanged over time,” the researchers of the Osteoporotic Fractures in Men (MrOS) study wrote.
The study included older men (aged ≥65 years) from the United States (n = 1919), Sweden (n=2495), and Hong Kong (n=1469) who had baseline T and E2 assessed by mass spectrometry.
During follow-up (mean, 5.7 years), the researchers determined rate of falls every 4 months, as well as associations between sex steroids and falls via generalized estimating equations.
According to study findings, the highest fall rate, as determined by fall reports/person/year, occurred in the United States (0.50), followed by Sweden (0.31) and Hong Kong (0.12).
Among the entire study population (n=5883), incident falls were linked with total T (odds ratio [OR] per standard deviation increase, 0.88; 95% CI, 0.86-0.91) and BioT (OR, 0.86; 95% CI, 0.83-0.88), after adjusting for age and prevalent falls. Specifically, those in the lowest quartile of total T (<346 ng/dL) and BioT (<190 ng/dL) levels were at the greatest risk for falls.
These associations remained, although they were slightly attenuated, after additional adjustment for physical performance variables, resulting in a 0.94 OR for total T (95% CI, 0.91-0.96) and a 0.91 OR for BioT (95% CI, 0.89-0.94).
There were no significant correlations between falls and E2, BioE2, and sex hormone-binding globulin.
In further analysis, falls were associated with total T and BioT in US and Swedish participants, but not in those from Hong Kong. With the latter finding, the researchers postulated that it “may be due to environmental factors rather than ethnic differences since total T and BioT predicted falls in MrOS US Asians.”
The researchers added that the effect of T on the risk for falling is at least partly mediated by muscle mass and physical performance.
“Both falls and bone strength parameters are independent predictors of fracture risk in older men,” they wrote. “With the present data, we propose that low serum T influences fracture risk via an increased risk of falls whereas low E2 might increase fracture risk mainly through reduced bone strength.”
Vandenput L, Mellström D, Laughlin GA, et al. Low testosterone, but not estradiol, is associated with incident falls in older men – the international MrOS Study [published online February 27, 2017]. J Bone Miner Res. 2017. doi:10.1002/jbmr.3088