“Previous testosterone trials in older men yielded equivocal and inconsistent results,” said coauthor and chair of the TTrials recruitment committee, Jane A. Cauley, Dr.P.H.
, professor in Pitt Public Health’s Department of Epidemiology
and principal investigator at the study’s Pittsburgh site. “We showed that testosterone improved men’s impression that their sexual function and walking ability had improved, suggesting that these effects are clinically important.”
The TTrials are a coordinated group of seven trials testing the effect of a testosterone gel compared with a placebo gel, and researchers have analyzed the results of the three primary trials – sexual function, physical function and vitality. They found that testosterone treatment increased the blood testosterone level in the men 65 and older to levels comparable to mid-normal for young men. Testosterone also improved all aspects of sexual function, including sexual activity, sexual desire and the ability to get an erection. Testosterone treatment did not significantly improve distance walked in six minutes when only men enrolled in the physical function trial were considered, but did increase the distance walked when all men in the TTrials were considered. The treatment did not improve energy, but did improve mood and depressive symptoms.
“The results of the TTrials show for the first time that testosterone treatment of older men who have unequivocally low testosterone levels does have some benefit,” said lead author and principal investigator of the TTrials Peter J. Snyder, M.D., a professor in the Division of Endocrinology, Diabetes and Metabolism at Penn. “However, decisions about testosterone treatment for these men also will depend on the results of the other four trials – cognitive function, bone, cardiovascular and anemia – and the risks of testosterone treatment.”
In 2003, the Institute of Medicine
reported that there was insufficient evidence to support any beneficial effect of testosterone in such men. This report was the impetus for TTrials, which are now the largest trials to examine the efficacy of testosterone treatment in men 65 and older whose testosterone levels are low due seemingly to age alone. TTrials researchers screened 51,085 men to find 790 who qualified with a sufficiently low testosterone level and who met other criteria; 78 of the men were enrolled from the Pittsburgh area.
The men enrolled were randomized into two groups: one to apply the daily testosterone gel and the other a daily placebo gel, for one year. Efficacy was then evaluated at months three, six, nine and 12. Sexual function was assessed by questionnaires; physical function was measured by questionnaires and the distance walked in six minutes; and vitality, mood and depressive symptoms also were evaluated using questionnaires.
Across the three trials, adverse events – including heart attack, stroke, other cardiovascular events and prostate conditions – were similar in men who received testosterone and those who received placebo. However, the number of men in the TTrials was too small to draw conclusions about the risk of testosterone treatment, which the researchers say would require a larger and longer trial.
The TTrials were conducted at 11 additional medical centers across the country: Albert Einstein College of Medicine, Baylor College of Medicine, Brigham and Women’s Hospital, Harbor-UCL Medical Center, University of Alabama at Birmingham, Northwestern University Feinberg School of Medicine, Puget Sound Health Care System, University of California at San Diego School of Medicine, University of Florida School of Medicine, University of Minnesota School of Medicine and Yale School of Medicine.
The TTrials were supported by NIH National Institute on Aging grant U01 AG030644, and supplemented by funds from the National Heart, Lung, and Blood Institute, National Institute of Neurological Diseases and Stroke, and National Institute of Child Health and Human Development. AbbVie
(formerly Solvay and Abbot Laboratories) also provided funding, AndroGel and placebo gel, but did not participate in the design or conduct of the trials, nor analysis or reporting of the data.