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05.05.2016

Testosterone not a miracle cure for older men

Amazing stuff, testosterone. Put it in a gel and get older men to spread it over their skin, and lo and behold: fading Lotharios come back to life. They become fitter and their sex life blossoms. At least, that's what the popular press would have us believe. But it's a shame that much of the popular media reporting is done by overworked and underpaid text slaves, who don't have the time to read a study properly.

The commotion
In February 2016 the media was crawling with reports like the one published on Medical News Today. [medicalnewstoday.com 19 February 2016] It was about an American scientific study published in the New England Journal of Medicine.

The study was partly financed by AbbVie, the manufacturer of the testosterone gel AndroGel.

The study
The researchers analysed data from over seven hundred men over the age of 65, all of whom had relatively low levels of testosterone in their blood. The men rubbed 5 g AndroGel on to their skin every day for a year. As a result the concentration of testosterone in their blood rose to the level you'd normally find in men aged 20-40.

The results
The two figures below are from the study. They represent the strongest positive effects of the testosterone supplementation. The first figure indicates how many times more often or less often the men had sex each week. The sexual activity of the men in the placebo group remained more or less constant; the men who had used the testosterone gel during the trial had sex about half a time more often each week than before they started using the testosterone.

The pro-sexual effect declined as the trial continued. In the last month of the experiment the men in the testosterone group only had sex once more in five weeks than they had done before administration started.

The effect was not big, but it was statistically significant. None of the other effects that the researchers measured were as big as this.

The figure below suggests that the men became fitter. It shows the percentage of men who as a result of the testosterone or a placebo were able to run at least 50 metres more in six minutes than before administration.

The figure is a little confusing, so being our industrious selves we have made our own figure based on the data from the study, which you can see below. It shows the average number of metres that the men were able to run in six minutes. That's easier to understand.

Before the trial started the men were capable of running 387 metres. At the end of the trial, for the men that had used the testosterone gel, the distance had increased by 14 metres. For the men in the placebo group the distance increased by 7 metres.

More men in the testosterone group developed prostate cancer than in the placebo group; more also developed a raised PSA and higher haematocrit levels.

None of these effects were statistically significant either, but the researchers suggest this might have been because the number of subjects was too small. "The number of participants was too few to draw conclusions about the risks of testosterone treatment", the researchers write.

Conclusion
The reports on this study in the popular media are exaggerated. The pro-sexual effect of testosterone is the only significant effect that the researchers found – and that's not spectacular either. And did the study demonstrate that testosterone administration is safe? No.

Source:
N Engl J Med 2016;374:611-24.

More:
Testosterone too dangerous for older men – trial stopped 21.07.2010

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