Symptomatic benefits of testosterone treatment in patient subgroups: a systematic review, individual participant data meta-analysis, and aggregate data meta-analysis.

BACKGROUND: Testosterone replacement therapy is known to improve sexual function in men younger than 40 years with pathological hypogonadism. However, the extent to which testosterone alleviates sexual dysfunction in older men and men with obesity is unclear, despite the fact that testosterone is being increasingly prescribed to these patient populations. We aimed to evaluate whether subgroups of men with low testosterone derive any symptomatic benefit from testosterone treatment. METHODS: We did a systematic review and meta-analysis to evaluate characteristics associated with symptomatic benefit of testosterone treatment versus placebo in men aged 18 years and older with a baseline serum total testosterone concentration of less than 12 nmol/L. We searched major electronic databases (MEDLINE, Embase, Science Citation Index, and the Cochrane Central Register of Controlled Trials) and clinical trial registries for reports published in English between Jan 1, 1992, and Aug 27, 2018. Anonymised individual participant data were requested from the investigators of all identified trials. Primary (cardiovascular) outcomes from this analysis have been published previously. In this report, we present the secondary outcomes of sexual function, quality of life, and psychological outcomes at 12 months. We did a one-stage individual participant data meta-analysis with a random-effects linear regression model, and a two-stage meta-analysis integrating individual participant data with aggregated data from studies that did not provide individual participant data. This study is registered with PROSPERO, CRD42018111005. FINDINGS: 9871 citations were identified through database searches. After exclusion of duplicates and publications not meeting inclusion criteria, 225 full texts were assessed for inclusion, of which 109 publications reporting 35 primary studies (with a total 5601 participants) were included. Of these, 17 trials provided individual participant data (3431 participants; median age 67 years [IQR 60-72]; 3281 [97%] of 3380 aged ≥40 years) Compared with placebo, testosterone treatment increased 15-item International Index of Erectile Function (IIEF-15) total score (mean difference 5·52 [95% CI 3·95-7·10]; τ2=1·17; n=1412) and IIEF-15 erectile function subscore (2·14 [1·40-2·89]; τ2=0·64; n=1436), reaching the minimal clinically important difference for mild erectile dysfunction. These effects were not found to be dependent on participant age, obesity, presence of diabetes, or baseline serum total testosterone. However, absolute IIEF-15 scores reached during testosterone treatment were subject to thresholds in patient age and baseline serum total testosterone. Testosterone significantly improved Aging Males' Symptoms score, and some 12-item or 36-item Short Form Survey quality of life subscores compared with placebo, but it did not significantly improve psychological symptoms (measured by Beck Depression Inventory). INTERPRETATION: In men aged 40 years or older with baseline serum testosterone of less than 12 nmol/L, short-to-medium-term testosterone treatment could provide clinically meaningful treatment for mild erectile dysfunction, irrespective of patient age, obesity, or degree of low testosterone. However, due to more severe baseline symptoms, the absolute level of sexual function reached during testosterone treatment might be lower in older men and men with obesity. FUNDING: National Institute for Health and Care Research Health Technology Assessment Programme.

Aging and declining testosterone: past, present, and hopes for the future.

As men age, serum testosterone (T) levels decline, whereas serum luteinizing hormone (LH) levels increase somewhat or remain unchanged. Age-related reductions in T levels may be associated with alterations in body composition; energy level; muscle strength; physical, sexual, and cognitive functions; and mood. The predominant contributor to the decline in serum T levels is the decreased ability of the aging testes to make T. As in humans, the Brown Norway rat demonstrates age-related reductions in serum T levels in the setting of unchanged or modestly increased serum LH levels. In this rat model, the ability of aged Leydig cells, the terminally differentiated T-producing cells of the testis, to produce T in response to LH stimulation is significantly diminished. This review begins with a discussion of what is known of the molecular mechanisms by which T synthesis declines with Leydig cell aging. It concludes with a brief history of T replacement therapy, current guidelines, controversies related to T replacement therapy in older men, and proposed future clinical directions.