Older men who have low testosterone levels are at substantially higher risk of falling than are their peers who have normal or high levels, reported Dr. Eric Orwoll and his associates in the Osteoporotic Fractures in Men study, which is known as MrOS.
Several of the factors associated with increased risk of falling—including reduced muscle mass, decreased muscle strength, and decreased physical performance—are thought to be linked to age-related declines in androgen levels, but “no prospective data document this association,” Dr. Orwoll, of Oregon Health and Science University, Portland, and his associates said in the Oct. 23 issue of the Archives of Internal Medicine.
They examined the issue using data from the MrOS study, a multicenter community-based cohort study of approximately 6,000 men aged 65 and older that was designed to identify risk factors for falls and fractures.
A subgroup of 2,623 subjects who were followed at 4-month intervals for a mean of 4 years formed the basis of the study. The mean age was 73 years, and most of the participants rated their general health as good to excellent.
Falls were very common, with 56% of the men reporting at least one fall over the course of follow-up. Falls were more common at older ages, with more than 20% of the men over age 80 reporting that they had fallen five times or more, compared with only 10% of men aged 65–69 years.
The risk of falling increased in men with declining levels of bioavailable testosterone.
“Fall risk in men in the lowest quartile of baseline bioavailable testosterone concentration was more than 40% greater than that in men in the highest quartile, [both] before and after adjustment for physical performance,” Dr. Orwoll and his associates noted (Arch. Intern. Med. 2006;166: 2124–31).
When they repeated their analysis using data on only the healthiest subjects, this association did not change.
Men with lower testosterone levels also were at higher risk for multiple falls (more than 2 per year).
The risk of falls was also greater in men who had reduced levels of muscle strength or physical function.
However, when these factors were statistically controlled for, the effect of testosterone level on fall risk was unchanged. This demonstrates that the association between testosterone level and fall risk is strong regardless of the subject's physical performance and muscle strength.
“There may be other androgen-dependent mechanisms that contribute to the causation of falling,” such as testosterone's effects on visual performance, cognition, or neuromuscular coordination, the investigators noted.
Given that their large study population was geographically and racially diverse, the study findings “are likely to be broadly applicable to similarly aged, generally healthy U.S. men,” the researchers pointed out.
“These results provide additional justification for trials of testosterone supplementation in older men,” Dr. Orwoll and his associates said.