text_1: Testosterone replacement therapy may slow the progression of COPD
text_2: This release summarizes an observational study noting a relationship with two groups of men (middle aged and older), their consumption of testosterone replacement therapy and whether they are hospitalized for respiratory problems. It found that testosterone replacement therapy users had a decrease in respiratory hospitalizations compared with non-users. While observational studies such as these are useful and hypothesis generating, they do not have the strength of a randomized, blinded trial and hence one cannot conclude that such associations are causal. Better information about the harms, costs and conflicts of interests of the researchers would have made this a better news release. If testosterone replacement therapy (TRT) slows the progression of COPD in men by producing a positive lung function, this could indeed be a public health advance. Observational studies, however, are problematic in that the two cohorts of men observed (those who take TRT and those who don’t) may be different in other fundamental ways. There could, for example, be a “healthy user bias” in that the TRT cohort of men may be naturally healthier at the start, and that any improvements in COPD function may just be a function of their basic overall health. Studies like these allow us to draw conclusions, but only that there is an association — not that TRT caused a reduction in COPD.