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.

Experience with testosterone replacement in the elderly

To date, most of the studies of androgen replacement have been done with healthy older men (age > or = 55 years), and almost no data are available for frail elderly individuals. Treatment effects that make a relatively small difference in younger, more robust individuals may have a greater effect on the elderly, whose improvement in functioning and level of activity may be more dramatic. However, the frail elderly individual is also more vulnerable to adverse effects from treatment, and these potential risks and benefits must be weighed.

Testosterone replacement therapy in older adult men

Serum testosterone levels decline slowly with normal ageing in men and, although all men are not destined to become hypogonadal as they age, the prevalence of androgen deficiency in the older male is not insignificant. Over the past several decades, there has been an increasing interest in evaluating whether testosterone therapy (male HRT) might be beneficial for certain older men in preventing or reversing some aspects of ageing. The major androgen target organs of interest with regard to beneficial effects of male HRT include bone, muscle, adipose tissue, the cardiovascular system and the central nervous system (libido and aspects of mood). At the same time, potential adverse effects of male HRT on target organs such as the prostate continue to be evaluated. It is the purpose of this review to summarize the information to date with regard to testosterone replacement therapy in the older man and to discuss areas where more research and clinical information need to be forthcoming. Hormonal replacement therapy (HRT) for post-menopausal women has been studied and discussed for many years. The idea of male HRT, however, is a relatively recent development, with increasing interest in this area occurring only over the past two decades. Reasons for this nascent enthusiasm include burgeoning evidence that testosterone levels decline with normal male ageing (and with age-associated diseases) and an interest in preventing age-related dysfunction and prolonging quality life among an ever increasing population of older adults. The decline in testosterone with age often parallels unfavourable changes in organs upon which androgens act and the goal of male HRT would be to prevent, stabilize or even reverse some of these detrimental target-organ changes.

Male hormone replacement therapy including "andropause"

Adult onset male hypogonadism and the testosterone deficiency of the aging male often are under-recognized entities. The etiologies, presentation, and diagnosis of hypogonadism and andropause in the adult male are presented. The expected therapeutic goals, potential treatment risks, and management of androgen replacement therapy for the adult man are reviewed. The advantages and disadvantages of the various androgen delivery systems currently available and under investigation are discussed.

Combined analysis of two multicenter studies of finasteride 5 mg in the treatment of symptomatic benign prostatic hyperplasia

The purpose of this paper is to examine effects of finasteride 5 mg across different age groups in an ethnically diverse population of men with symptomatic benign prostatic hyperplasia (BPH) seen in community urology and primary care practices. Data were combined from two previous placebo-controlled randomised trials of finasteride that evaluated changes in urinary symptoms, blinded global assessments of urologic status, adverse experiences, and effects on dihydrotestosterone (DHT) and prostate-specific antigen (PSA) in over 4500 men. Finasteride showed a favourable efficacy and tolerability profile in this large ethnically diverse population and was similarly effective in middle-aged and older men with BPH and prostate gland enlargement.

Testosterone and the aging male

The number and magnitude of studies involving testosterone-supplementation therapy in older men are limited. In addition, many studies to date have not been blinded or controlled, were reported in abstract form only, and had involved a variety of androgen-replacement regimens and outcomes measurements. Nonetheless, an overview of the data suggests there is real potential for supplementation therapy to improve bone mass and muscle mass and strength in this age group. Affects on mood, sexual function, and cognition are less clear but may be meaningful in certain men. Questions still remain, however, on the magnitude and longevity of the beneficial effects of testosterone supplementation in the older man and whether only certain subgroups of men would truly benefit from therapy. More importantly, the long-term risks of androgen therapy in this age group really are not known, especially in the areas of cardiovascular disease and prostate diseases. Presently, men who use androgen-supplementation therapy for age-related "testosterone deficiency" should consider this as a gamble.

Efficacy and tolerability of finasteride in symptomatic benign prostatic hyperplasia: a primary care study. Primary Care Investigator Study Group

Because increasing numbers of men are seeking treatment for benign prostatic hyperplasia (BPH) from primary care physicians, we sought to assess the efficacy and tolerability of finasteride in a primary care setting. In this randomized, double-masked study, 2,112 men with symptomatic BPH received either finasteride (n = 1,589) or placebo (n = 523) for 1 year. At 3, 6, 9, and 12 months, urinary symptoms were measured using the American Urological Association Symptom Index (AUASI). Quality of life was assessed using the BPH Impact Index (BII), which assessed bother, worry, physical discomfort, and restriction in activities. Both patients and investigators assessed overall urologic status. Investigators assessed the effect of the drug on plasma lipids in a subset of patients. Patients treated with finasteride had a statistically significant mean decrease in AUASI scores compared with patients treated with placebo beginning at month 6 and continuing throughout the study. At month 12, adjusted mean decreases in AUASI scores were -4.96 for finasteride versus -3.71 for placebo. Statistically significant differences in favor of finasteride were also noted on BII at months 9 and 12. Patient and investigator overall assessments showed greater improvement in the finasteride group beginning at month 6. The incidence of drug-related sexual adverse experiences was significantly greater in finasteride-treated patients but led to withdrawal in only 2.2% of these patients. Overall lipid profile was not significantly altered in either group. Based on improvement in symptoms and quality of life, and on its favorable tolerability profile, finasteride should be considered by primary care physicians for management of symptomatic BPH.