Methods for the estimation of direct and indirect vaccination effects by combining data from individual- and cluster-randomized trials

Both individually and cluster randomized study designs have been used for vaccine trials to assess the effects of vaccine on reducing the risk of disease or infection. The choice between individually and cluster randomized designs is often driven by the target estimand of interest (eg, direct versus total), statistical power, and, importantly, logistic feasibility. To combat emerging infectious disease threats, especially when the number of events from one single trial may not be adequate to obtain vaccine effect estimates with a desired level of precision, it may be necessary to combine information across multiple trials. In this article, we propose a model formulation to estimate the direct, indirect, total, and overall vaccine effects combining data from trials with two types of study designs: individual-randomization and cluster-randomization, based on a Cox proportional hazards model, where the hazard of infection depends on both vaccine status of the individual as well as the vaccine status of the other individuals in the same cluster. We illustrate the use of the proposed model and assess the potential efficiency gain from combining data from multiple trials, compared to using data from each individual trial alone, through two simulation studies, one of which is designed based on a cholera vaccine trial previously carried out in Matlab, Bangladesh.

Long-term Outcomes with Spinal versus General Anesthesia for Hip Fracture Surgery: A Randomized Trial

BACKGROUND

The effects of spinal versus general anesthesia on long-term outcomes have not been well studied. This study tested the hypothesis that spinal anesthesia is associated with better long-term survival and functional recovery than general anesthesia.

METHODS

A prespecified analysis was conducted of long-term outcomes of a completed randomized superiority trial that compared spinal anesthesia versus general anesthesia for hip fracture repair. Participants included previously ambulatory patients 50 yr of age or older at 46 U.S. and Canadian hospitals. Patients were randomized 1:1 to spinal or general anesthesia, stratified by sex, fracture type, and study site. Outcome assessors and investigators involved in the data analysis were masked to the treatment arm. Outcomes included survival at up to 365 days after randomization (primary); recovery of ambulation among 365-day survivors; and composite endpoints for death or new inability to ambulate and death or new nursing home residence at 365 days. Patients were included in the analysis as randomized.

RESULTS

A total of 1,600 patients were enrolled between February 12, 2016, and February 18, 2021; 795 were assigned to spinal anesthesia, and 805 were assigned to general anesthesia. Among 1,599 patients who underwent surgery, vital status information at or beyond the final study interview (conducted at approximately 365 days after randomization) was available for 1,427 (89.2%). Survival did not differ by treatment arm; at 365 days after randomization, there were 98 deaths in patients assigned to spinal anesthesia versus 92 deaths in patients assigned to general anesthesia (hazard ratio, 1.08; 95% CI, 0.81 to 1.44, P = 0.59). Recovery of ambulation among patients who survived a year did not differ by type of anesthesia (adjusted odds ratio for spinal vs. general, 0.87; 95% CI, 0.67 to 1.14; P = 0.31). Other outcomes did not differ by treatment arm.

CONCLUSIONS

Long-term outcomes were similar with spinal versus general anesthesia.

EDITOR’S PERSPECTIVE

Testosterone Treatment and Fractures in Men with Hypogonadism

BACKGROUND

Testosterone treatment in men with hypogonadism improves bone density and quality, but trials with a sufficiently large sample and a sufficiently long duration to determine the effect of testosterone on the incidence of fractures are needed.

METHODS

In a subtrial of a double-blind, randomized, placebo-controlled trial that assessed the cardiovascular safety of testosterone treatment in middle-aged and older men with hypogonadism, we examined the risk of clinical fracture in a time-to-event analysis. Eligible men were 45 to 80 years of age with preexisting, or high risk of, cardiovascular disease; one or more symptoms of hypogonadism; and two morning testosterone concentrations of less than 300 ng per deciliter (10.4 nmol per liter), in fasting plasma samples obtained at least 48 hours apart. Participants were randomly assigned to apply a testosterone or placebo gel daily. At every visit, participants were asked if they had had a fracture since the previous visit. If they had, medical records were obtained and adjudicated.

RESULTS

The full-analysis population included 5204 participants (2601 in the testosterone group and 2603 in the placebo group). After a median follow-up of 3.19 years, a clinical fracture had occurred in 91 participants (3.50%) in the testosterone group and 64 participants (2.46%) in the placebo group (hazard ratio, 1.43; 95% confidence interval, 1.04 to 1.97). The fracture incidence also appeared to be higher in the testosterone group for all other fracture end points.

CONCLUSIONS

Among middle-aged and older men with hypogonadism, testosterone treatment did not result in a lower incidence of clinical fracture than placebo. The fracture incidence was numerically higher among men who received testosterone than among those who received placebo. (Funded by AbbVie and others; TRAVERSE ClinicalTrials.gov number, NCT03518034.).

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.

Outcomes with spinal versus general anesthesia for patients with and without preoperative cognitive impairment: Secondary analysis of a randomized clinical trial

INTRODUCTION

The effect of spinal versus general anesthesia on the risk of postoperative delirium or other outcomes for patients with or without cognitive impairment (including dementia) is unknown.

METHODS

Post hoc secondary analysis of a multicenter pragmatic trial comparing spinal versus general anesthesia for adults aged 50 years or older undergoing hip fracture surgery.

RESULTS

Among patients randomized to spinal versus general anesthesia, new or worsened delirium occurred in 100/295 (33.9%) versus 107/283 (37.8%; odds ratio [OR] 0.85; 95% confidence interval [CI] 0.60 to 1.19) among persons with cognitive impairment and 70/432 (16.2%) versus 71/445 (16.0%) among persons without cognitive impairment (OR 1.02; 95% CI 0.71 to 1.47, p = 0.46 for interaction). Delirium severity, in-hospital complications, and 60-day functional recovery did not differ by anesthesia type in patients with or without cognitive impairment.

DISCUSSION

Anesthesia type is not associated with differences in delirium and functional outcomes among persons with or without cognitive impairment.

Bringing data monitoring committee charters into the sunlight

Clinical trials investigating novel or high risk interventions, or studying vulnerable participants, often use a data monitoring committee to oversee the progress of the trial. The data monitoring committee serves both an ethical and a scientific function, by protecting the interests of trial participants while ensuring the integrity of the trial results. A data monitoring committee charter, which typically describes the procedures by which data monitoring committees operate, contains details about the data monitoring committee's organizational structure, membership, meeting frequency, sequential monitoring guidelines, and the overall contents of data monitoring committee reports for interim review. These charters, however, are generally not reviewed by outside entities and are rarely publicly available. The result is that a key component of trial oversight remains in the dark. We recommend that ClinicalTrials.gov modify its system to allow uploading of data monitoring committee charters, as is already possible for other important study documents and that clinical trialists take advantage of this opportunity to voluntarily upload the data monitoring committee charter for trials that have one. The resulting cache of publicly available data monitoring committee charters should provide important insights for those interested in a particular trial, as well as for meta-researchers who wish to understand and potentially improve how this important component of trial oversight is actually being applied.

Monitoring Multiple U.S. Government-Supported Covid-19 Vaccine Trials

Monitoring U.S. Government-Supported Covid-19 Vaccine TrialsOperation Warp Speed was a partnership created to accelerate the development of Covid-19 vaccines. The National Institutes of Health oversaw one data and safety monitoring board to review/monitor all Operation Warp Speed trials. This article describes the challenges faced in monitoring these trials and provides ideas for future similar endeavors.

Improving the Approach to Defining, Classifying, Reporting and Monitoring Adverse Events in Seriously Ill Older Adults: Recommendations from a Multi-stakeholder Convening

BACKGROUND

Clinical trials are needed to study topics relevant to older adults with serious illness. Investigators conducting clinical trials with this population are challenged by how to appropriately define, classify, report, and monitor serious and non-serious adverse events (SAEs/AEs), given that some traditionally reported AEs (pressure ulcers, delirium) and SAEs (death, hospitalization) are common in persons with serious illness, and may be consistent with their goals of care.

OBJECTIVES

A multi-stakeholder group convened to establish greater clarity on and new approaches to address this critical issue.

PARTICIPANTS

Thirty-two study investigators, members of regulatory and sponsor agencies, and patient stakeholders took part.

APPROACH

The group met virtually four times and, using a collaborative approach, conducted a survey, select interviews, and reviewed regulatory guidance to collectively define the problem and identify a new approach.

RESULTS

SAE/AE challenges fell into two areas: (1) definitions and classifications, including (a) implausible relationships, (b) misalignment with patient-centered care goals, and (c) well-known associations, and (2) reporting and monitoring, including (a) limited guidance, (b) inconsistent standards across regulators, and (c) Data Safety Monitoring Board (DSMB) member knowledge gaps. Problems largely reflected practice norms rather than regulatory requirements that already support context-specific and aggregate reporting. Approaches can be improved by adopting principles that better align strategies for addressing adverse events with the type of intervention being tested, favoring routine and aggregate over expedited reporting, and prioritizing how SAE/AEs relate to patient-centered care goals. Reporting plans and decisions should follow an algorithm underpinned by these principles.

CONCLUSIONS

Adoption of the proposed approach-and supporting it with education and better alignment with regulatory guidance and procedures-could improve the quality and efficiency of clinical trials' safety involving older adults with serious illness and other vulnerable populations.

A platform trial design for preventive vaccines against Marburg virus and other emerging infectious disease threats

BACKGROUND

The threat of a possible Marburg virus disease outbreak in Central and Western Africa is growing. While no Marburg virus vaccines are currently available for use, several candidates are in the pipeline. Building on knowledge and experiences in the designs of vaccine efficacy trials against other pathogens, including SARS-CoV-2, we develop designs of randomized Phase 3 vaccine efficacy trials for Marburg virus vaccines.

METHODS

A core protocol approach will be used, allowing multiple vaccine candidates to be tested against controls. The primary objective of the trial will be to evaluate the effect of each vaccine on the rate of virologically confirmed Marburg virus disease, although Marburg infection assessed via seroconversion could be the primary objective in some cases. The overall trial design will be a mixture of individually and cluster-randomized designs, with individual randomization done whenever possible. Clusters will consist of either contacts and contacts of contacts of index cases, that is, ring vaccination, or other transmission units.

RESULTS

The primary efficacy endpoint will be analysed as a time-to-event outcome. A vaccine will be considered successful if its estimated efficacy is greater than 50% and has sufficient precision to rule out that true efficacy is less than 30%. This will require approximately 150 total endpoints, that is, cases of confirmed Marburg virus disease, per vaccine/comparator combination. Interim analyses will be conducted after 50 and after 100 events. Statistical analysis of the trial will be blended across the different types of designs. Under the assumption of a 6-month attack rate of 1% of the participants in the placebo arm for both the individually and cluster-randomized populations, the most likely sample size is about 20,000 participants per arm.

CONCLUSION

This event-driven design takes into the account the potentially sporadic spread of Marburg virus. The proposed trial design may be applicable for other pathogens against which effective vaccines are not yet available.

Early Termination of Clinical Trials for Futility - Considerations for a Data and Safety Monitoring Board

Early Termination of Clinical Trials for FutilityClinical trials may be stopped for futility if there is little or no chance of demonstrating the hoped-for effect. Reasons include evidence of no treatment effect, substantial missing data that would unacceptably undermine trial conclusions, or event rates too low to support meaningful comparisons. This review examines issues faced by DSMBs in such settings.

Pain, Analgesic Use, and Patient Satisfaction With Spinal Versus General Anesthesia for Hip Fracture Surgery : A Randomized Clinical Trial

BACKGROUND

The REGAIN (Regional versus General Anesthesia for Promoting Independence after Hip Fracture) trial found similar ambulation and survival at 60 days with spinal versus general anesthesia for hip fracture surgery. Trial outcomes evaluating pain, prescription analgesic use, and patient satisfaction have not yet been reported.

OBJECTIVE

To compare pain, analgesic use, and satisfaction after hip fracture surgery with spinal versus general anesthesia.

DESIGN

Preplanned secondary analysis of a pragmatic randomized trial. (ClinicalTrials.gov: NCT02507505).

SETTING

46 U.S. and Canadian hospitals.

PARTICIPANTS

Patients aged 50 years or older undergoing hip fracture surgery.

INTERVENTION

Spinal or general anesthesia.

MEASUREMENTS

Pain on postoperative days 1 through 3; 60-, 180-, and 365-day pain and prescription analgesic use; and satisfaction with care.

RESULTS

A total of 1600 patients were enrolled. The average age was 78 years, and 77% were women. A total of 73.5% (1050 of 1428) of patients reported severe pain during the first 24 hours after surgery. Worst pain over the first 24 hours after surgery was greater with spinal anesthesia (rated from 0 [no pain] to 10 [worst pain imaginable]; mean difference, 0.40 [95% CI, 0.12 to 0.68]). Pain did not differ across groups at other time points. Prescription analgesic use at 60 days occurred in 25% (141 of 563) and 18.8% (108 of 574) of patients assigned to spinal and general anesthesia, respectively (relative risk, 1.33 [CI, 1.06 to 1.65]). Satisfaction was similar across groups.

LIMITATION

Missing outcome data and multiple outcomes assessed.

CONCLUSION

Severe pain is common after hip fracture. Spinal anesthesia was associated with more pain in the first 24 hours after surgery and more prescription analgesic use at 60 days compared with general anesthesia.

PRIMARY FUNDING SOURCE

Patient-Centered Outcomes Research Institute.

Benefit-risk assessment and reporting in clinical trials of chronic pain treatments: IMMPACT recommendations

ABSTRACT

Chronic pain clinical trials have historically assessed benefit and risk outcomes separately. However, a growing body of research suggests that a composite metric that accounts for benefit and risk in relation to each other can provide valuable insights into the effects of different treatments. Researchers and regulators have developed a variety of benefit-risk composite metrics, although the extent to which these methods apply to randomized clinical trials (RCTs) of chronic pain has not been evaluated in the published literature. This article was motivated by an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting and is based on the expert opinion of those who attended. In addition, a review of the benefit-risk assessment tools used in published chronic pain RCTs or highlighted by key professional organizations (ie, Cochrane, European Medicines Agency, Outcome Measures in Rheumatology, and U.S. Food and Drug Administration) was completed. Overall, the review found that benefit-risk metrics are not commonly used in RCTs of chronic pain despite the availability of published methods. A primary recommendation is that composite metrics of benefit-risk should be combined at the level of the individual patient, when possible, in addition to the benefit-risk assessment at the treatment group level. Both levels of analysis (individual and group) can provide valuable insights into the relationship between benefits and risks associated with specific treatments across different patient subpopulations. The systematic assessment of benefit-risk in clinical trials has the potential to enhance the clinical meaningfulness of RCT results.

Determinants of hospital outcomes for patients with COVID-19 in the University of Pennsylvania Health System

There is growing evidence that racial and ethnic minorities bear a disproportionate burden from COVID-19. Temporal changes in the pandemic epidemiology and diversity in the clinical course require careful study to identify determinants of poor outcomes. We analyzed 6255 hospitalized individuals with PCR-confirmed SARS-CoV-2 infection from one of 5 hospitals in the University of Pennsylvania Health System between March 2020 and March 2021, using electronic health records to assess risk factors and outcomes through 8 weeks post-admission. Discharge, readmission and mortality outcomes were analyzed in a multi-state model with multivariable Cox models for each transition. Mortality varied markedly over time, with cumulative incidence (95% CI) 30 days post-admission of 19.1% (16.9, 21.3) in March-April 2020, 5.7% (4.2, 7.5) in July-October 2020 and 10.5% (9.1,12.0) in January-March 2021; 26% of deaths occurred after discharge. Average age (SD) at admission varied from 62.7 (17.6) to 54.8 (19.9) to 60.5 (18.1); mechanical ventilation use declined from 21.3% to 9-11%. Compared to Caucasian, Black race was associated with more severe disease at admission, higher rates of co-morbidities and residing in a low-income zip code. Between-race risk differences in mortality risk diminished in multivariable models; while admitting hospital, increasing age, admission early in the pandemic, and severe disease and low blood pressure at admission were associated with increased mortality hazard. Hispanic ethnicity was associated with fewer baseline co-morbidities and lower mortality hazard (0.57, 95% CI: 0.37, .087). Multi-state modeling allows for a unified framework to analyze multiple outcomes throughout the disease course. Morbidity and mortality for hospitalized COVID-19 patients varied over time but post-discharge mortality remained non-trivial. Black race was associated with more risk factors for morbidity and with treatment at hospitals with lower mortality. Multivariable models suggest there are not between-race differences in outcomes. Future work is needed to better understand the identified between-hospital differences in mortality.

Relation of Testosterone, Dihydrotestosterone, and Estradiol With Changes in Outcomes Measures in the Testosterone Trials

CONTEXT

Many effects of testosterone are mediated through dihydrotestosterone (DHT) and estradiol.

OBJECTIVE

To determine the relative contributions of each hormone to the observed effects of testosterone treatment in older men with hypogonadism.

METHODS

Using data from the Testosterone Trials, we assessed the association of changes in total testosterone, estradiol, and DHT levels over 12 months of testosterone treatment with hemoglobin, high-density lipoprotein (HDL) cholesterol, volumetric bone mineral density (vBMD) of lumbar spine, sexual desire, and prostate-specific antigen (PSA). We used random forests to model the associations of predicted mean changes in outcomes with change in each hormone at low, mean, or high change in the other 2 hormones. Stepwise regression models were run to confirm the findings of random forests.

RESULT

Predicted increases in hemoglobin and sexual desire were greater with larger increases in estradiol and were larger with high change in DHT compared with low change in DHT. Greater increases in estradiol were associated with larger decreases in HDL cholesterol; this association did not vary according to changes in DHT or testosterone. Change in vBMD was most robustly associated with change in estradiol and was greater with high change in testosterone and DHT. There was no consistent relation between change in PSA and change in any hormone.

CONCLUSION

Change in estradiol level was the best predictor not only of the change in vBMD and sexual desire but also of the changes in hemoglobin and HDL cholesterol. Consideration of testosterone, estradiol, and DHT together offers a superior prediction of treatment response in older hypogonadal men than testosterone alone.

Spinal Anesthesia or General Anesthesia for Hip Surgery in Older Adults

BACKGROUND

The effects of spinal anesthesia as compared with general anesthesia on the ability to walk in older adults undergoing surgery for hip fracture have not been well studied.

METHODS

We conducted a pragmatic, randomized superiority trial to evaluate spinal anesthesia as compared with general anesthesia in previously ambulatory patients 50 years of age or older who were undergoing surgery for hip fracture at 46 U.S. and Canadian hospitals. Patients were randomly assigned in a 1:1 ratio to receive spinal or general anesthesia. The primary outcome was a composite of death or an inability to walk approximately 10 ft (3 m) independently or with a walker or cane at 60 days after randomization. Secondary outcomes included death within 60 days, delirium, time to discharge, and ambulation at 60 days.

RESULTS

A total of 1600 patients were enrolled; 795 were assigned to receive spinal anesthesia and 805 to receive general anesthesia. The mean age was 78 years, and 67.0% of the patients were women. A total of 666 patients (83.8%) assigned to spinal anesthesia and 769 patients (95.5%) assigned to general anesthesia received their assigned anesthesia. Among patients in the modified intention-to-treat population for whom data were available, the composite primary outcome occurred in 132 of 712 patients (18.5%) in the spinal anesthesia group and 132 of 733 (18.0%) in the general anesthesia group (relative risk, 1.03; 95% confidence interval [CI], 0.84 to 1.27; P = 0.83). An inability to walk independently at 60 days was reported in 104 of 684 patients (15.2%) and 101 of 702 patients (14.4%), respectively (relative risk, 1.06; 95% CI, 0.82 to 1.36), and death within 60 days occurred in 30 of 768 (3.9%) and 32 of 784 (4.1%), respectively (relative risk, 0.97; 95% CI, 0.59 to 1.57). Delirium occurred in 130 of 633 patients (20.5%) in the spinal anesthesia group and in 124 of 629 (19.7%) in the general anesthesia group (relative risk, 1.04; 95% CI, 0.84 to 1.30).

CONCLUSIONS

Spinal anesthesia for hip-fracture surgery in older adults was not superior to general anesthesia with respect to survival and recovery of ambulation at 60 days. The incidence of postoperative delirium was similar with the two types of anesthesia. (Funded by the Patient-Centered Outcomes Research Institute; REGAIN ClinicalTrials.gov number, NCT02507505.).

Effect of testosterone treatment on the trabecular bone score in older men with low serum testosterone

The trabecular bone score (TBS) is an indirect measure of vertebral bone microarchitecture. Our objective was to examine the effect of testosterone treatment on TBS. One hundred and ninety-seven hypogonadal men were randomized to testosterone or placebo. After 12 months, there was no difference in the changes in TBS by randomized group.

INTRODUCTION

In the Bone Trial of the Testosterone Trials, testosterone treatment increased trabecular volumetric bone mineral density (vBMD) and increased estimated bone strength as determined by finite element analysis. The trabecular bone score (TBS) is an indirect measure of vertebral bone microarchitecture. TBS predicts fracture independent of lumbar spine areal (a) BMD. The objective of this study was to examine the effect of testosterone treatment on TBS compared to its effects on vBMD and aBMD.

METHODS

Two hundred and eleven men were enrolled in the Bone Trial of the Testosterone Trials. Of these, 197 men had 2 repeat TBS and vBMD measurements; 105 men were allocated to receive testosterone, and 92 men to placebo for 1 year. TBS, aBMD, and vBMD were assessed at baseline and month 12.

RESULTS

There was no difference in the percent change in TBS by randomized group: 1.6% (95% confidence intervals (CI) 0.2-3.9) in the testosterone group and 1.4% (95% CI -0.2, 3.1) in the placebo group. In contrast, vBMD increased by 6% (95% CI 4.5-7.5) in the testosterone group compared to 0.4% (95% CI -1.65-0.88) in the placebo groups.

CONCLUSIONS

TBS is not clinically useful in monitoring the 1-year effect of testosterone treatment on bone structure in older hypogonadal men.

AIDS and COVID: A tale of two pandemics and the role of statisticians

The world has experienced three global pandemics over the last half-century: HIV/AIDS, H1N1, and COVID-19. HIV/AIDS and COVID-19 are still with us and have wrought extensive havoc worldwide. There are many differences between these two infections and their global impacts, but one thing they have in common is the mobilization of scientific resources to both understand the infection and develop ways to combat it. As was the case with HIV, statisticians have been in the forefront of scientists working to understand transmission dynamics and the natural history of infection, determine prognostic factors for severe disease, and develop optimal study designs to assess therapeutics and vaccines.

Data and Safety Monitoring of COVID-19 Vaccine Clinical Trials

To speed the development of vaccines against SARS-CoV-2, the United States Federal Government has funded multiple phase 3 trials of candidate vaccines. A single 11-member data and safety monitoring board (DSMB) monitors all government-funded trials to ensure coordinated oversight, promote harmonized designs, and allow shared insights related to safety across trials. DSMB reviews encompass 3 domains: (1) the conduct of trials, including overall and subgroup accrual and data quality and completeness; (2) safety, including individual events of concern and comparisons by randomized group; and (3) interim analyses of efficacy when event-driven milestones are met. Challenges have included the scale and pace of the trials, the frequency of safety events related to the combined enrollment of over 100 000 participants, many of whom are older adults or have comorbid conditions that place them at independent risk of serious health events, and the politicized environment in which the trials have taken place.

Blinding in Clinical Trials for Chronic Liver Diseases

Within the field of randomized clinical trials (RCTs), the randomized double-blind placebo-controlled clinical trial is considered the most efficient means of simultaneously assessing the efficacy and safety of a medical therapy in a single trial. While many RCTs are conducted without blinding (open label), it is rare to encounter a blinded trial that does not randomize its subjects. Clinical trials for chronic liver diseases have adopted many of the practices set forth by RCTs in other chronic diseases, but blinding has often been difficult to properly implement. This review examines the rationale for blinding, common challenges to successful blinding, different mechanisms of unintentional unblinding in clinical trials for viral hepatitis and nonalcoholic steatohepatitis, and recommendations for blinding and design in future trials of treatments for liver disease.

Prediction of post-vaccination Guillain-Barré syndrome using data from a passive surveillance system

Purpose

Severe adverse events (AEs), such as Guillain‐Barré syndrome (GBS) occur rarely after influenza vaccination. We identify highly associated AEs with GBS and develop prediction models for GBS using the US Vaccine Adverse Event Reporting System (VAERS) reports following trivalent influenza vaccination (FLU3).

Methods

This study analyzed 80 059 reports from the US VAERS between 1990 and 2017. Several AEs were identified as highly associated with GBS and were used to develop the prediction model. Some common and mild AEs that were suspected to be underreported when GBS occurred simultaneously were removed from the final model. The analyses were validated using European influenza vaccine AEs data from EudraVigilance.

Results

Of the 80 059 reports, 1185 (1.5%) were annotated as GBS related. Twenty‐four AEs were identified as having strong association with GBS. The full prediction model, using age, sex, and all 24 AEs achieved an area under the receiver operating characteristic (ROC) curve (AUC) of 85.4% (90% CI: [83.8%, 86.9%]). After excluding the nine (e.g., pruritus, rash, injection site pain) likely underreported AEs, the final AUC became 77.5% (90% CI: [75.5%, 79.6%]). Two hundred and one (0.25%) reports were predicted as of high risk of GBS (predicted probability >25%) and 84 actually developed GBS.

Conclusion

The prediction performance demonstrated the potential of developing risk‐prediction models utilizing the VAERS cohort. Excluding the likely underreported AEs sacrificed some prediction power but made the model more interpretable and feasible. The high absolute risk of even a small number of AE combinations suggests the promise of GBS prediction within the VAERS dataset.

Clinically Important Differences for Mobility Measures Derived from the Testosterone Trials

BACKGROUND/OBJECTIVES

Accurate estimates of clinically important difference (CID) are required for interpreting the clinical importance of treatments to improve physical function, but CID estimates vary in different disease populations. We determined the CID for two common measures of walking ability in mobility-limited older men.

DESIGN

Longitudinal, multisite placebo-controlled trial.

SETTING/PARTICIPANTS

Men enrolled in the Testosterone Trials who had self-reported mobility limitation and gait speed less than 1.2 m/second (n = 429). Testosterone- and placebo-allocated participants were combined for this study.

RESULTS

Mean changes from baseline, adjusting for time-in-intervention and site, were 29.6, 13.2, 12.5, -2.4, and -32.6 m for 6MWD, and 15.4, 7.2, 2.1, -3.4, and -7.2 for PF10 in men who reported their mobility was "very/much better," "little better," "no change," "little worse," or "much worse," respectively. CID estimates using regression, ROC, and eCDF varied from 5.0-29.6 m for 6MWD, and 5.0-15.2 points for PF10.

CONCLUSION

CID estimates vary by the population studied and by the method and precision of measurement. Increases of 16 to 30 m for 6MWD and 5 to 15 points for PF10 over 12 months appear to be clinically meaningful in mobility-limited, older hypogonadal men. These CID estimates may be useful in the design of efficacy trials of therapies to improve physical function.

Markers of Iron Flux during Testosterone-Mediated Erythropoiesis in Older Men with Unexplained or Iron-Deficiency Anemia

CONTEXT

Testosterone treatment of hypogonadal men improves their hemoglobin, but the mechanism is not understood.

OBJECTIVE

To investigate possible mechanisms by which testosterone stimulates erythropoiesis in hypogonadal older men with unexplained or iron-deficiency anemia.

DESIGN

The Anemia Trial of The Testosterone Trials, a placebo-controlled study in older, hypogonadal men.

SETTING

Twelve academic medical centers.

PARTICIPANTS

A total of 95 hypogonadal men (testosterone < 275 ng/mL) ≥65 years with anemia (hemoglobin < 12.7 g/dL). They were classified as having unexplained (n = 58) or iron deficiency anemia (n = 37).

INTERVENTION

Testosterone or placebo gel for 1 year.

MAIN OUTCOME MEASURES

Markers of iron metabolism during the first 3 months of treatment.

RESULTS

Testosterone replacement significantly (P < 0.001) increased hemoglobin in the 58 men who had unexplained anemia (adjusted mean difference 0.58 g/dL; 95% confidence interval, 0.31-0.85). Testosterone replacement tended to increase hemoglobin in the 37 men who had iron deficiency (0.38 g/dL; -0.19, 0.95), but the response was more variable and not statistically significant (P = 0.19). In men with unexplained anemia, testosterone replacement suppressed hepcidin (-8.2 ng/mL; -13.7, -2.7; P = 0.004) and ferritin (-19.6 µg/L; -32.8, -6.3; P = 0.004), but in men with iron deficiency, testosterone replacement did not. The decrease in hepcidin was moderately correlated with the increase in hemoglobin in the men with unexplained anemia (correlation coefficient -0.35, P = 0.01) but not in those with iron deficiency anemia (correlation coefficient -0.07, P = 0.73).

CONCLUSIONS

Testosterone replacement of older hypogonadal men with unexplained anemia stimulates erythropoiesis associated with increased iron mobilization. This effect appears to be attenuated by iron deficiency.

Interpretation of chronic pain clinical trial outcomes: IMMPACT recommended considerations

Interpreting randomized clinical trials (RCTs) is crucial to making decisions regarding the use of analgesic treatments in clinical practice. In this article, we report on an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) consensus meeting organized by the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks, the purpose of which was to recommend approaches that facilitate interpretation of analgesic RCTs. We review issues to consider when drawing conclusions from RCTs, as well as common methods for reporting RCT results and the limitations of each method. These issues include the type of trial, study design, statistical analysis methods, magnitude of the estimated beneficial and harmful effects and associated precision, availability of alternative treatments and their benefit-risk profile, clinical importance of the change from baseline both within and between groups, presentation of the outcome data, and the limitations of the approaches used.

Real-world experiences with generating real-world evidence: Case Studies from PCORI's pragmatic clinical Studies program

BACKGROUND

Over the last decade, randomized studies evaluating outcomes of health care interventions conducted in real-world settings-often termed "pragmatic trials"-have come to be seen as an important means of obtaining relevant, actionable evidence to guide health care decisions. Despite extensive writing on methodological considerations in pragmatic trial design, limited information exists regarding the practical and logistical challenges encountered in carrying out rigorous randomized evaluations in highly representative, real-world contexts.

METHODS

The Patient Centered Outcomes Research Institute (PCORI) convened an expert panel in 2017 to examine common tradeoffs in study design and implementation through 3 "case studies" of in-progress, PCORI-funded pragmatic trials. This paper summarizes the findings of this panel, using the 3 examples to illustrate common implementation challenges encountered in pragmatic trials.

RESULTS

Investigators aimed to generate highly generalizable findings that could address real-world clinical decisions; however, practical considerations required that each study incorporate traditionally "explanatory" elements to achieve a "fit-for-purpose" approach to design and implementation. Within individual studies, efforts to balance pragmatic versus explanatory perspectives often involved multiple, diverse aspects of trial design and implementation, and the aspects of design and implementation where investigators reported encountering such tradeoffs varied across the three cases we examined.

CONCLUSIONS

Efforts to generate rigorous evidence that is generalizable to "real-world" practice require continuous and iterative efforts to balance "pragmatic" and "explanatory" perspectives. In each study examined, these tradeoffs were guided both by an overriding effort to maintain pragmatism and practical considerations that varied depending on the research question and study context.

Protocol adherence rates in superiority and noninferiority randomized clinical trials published in high impact medical journals

BACKGROUND/AIMS

Noninferiority clinical trials are susceptible to false confirmation of noninferiority when the intention-to-treat principle is applied in the setting of incomplete trial protocol adherence. The risk increases as protocol adherence rates decrease. The objective of this study was to compare protocol adherence and hypothesis confirmation between superiority and noninferiority randomized clinical trials published in three high impact medical journals. We hypothesized that noninferiority trials have lower protocol adherence and greater hypothesis confirmation.

METHODS

We conducted an observational study using published clinical trial data. We searched PubMed for active control, two-arm parallel group randomized clinical trials published in JAMA: The Journal of the American Medical Association, The New England Journal of Medicine, and The Lancet between 2007 and 2017. The primary exposure was trial type, superiority versus noninferiority, as determined by the hypothesis testing framework of the primary trial outcome. The primary outcome was trial protocol adherence rate, defined as the number of randomized subjects receiving the allocated intervention as described by the trial protocol and followed to primary outcome ascertainment (numerator), over the total number of subjects randomized (denominator). Hypothesis confirmation was defined as affirmation of noninferiority or the alternative hypothesis for noninferiority and superiority trials, respectively.

RESULTS

Among 120 superiority and 120 noninferiority trials, median and interquartile protocol adherence rates were 91.5 [81.4-96.7] and 89.8 [83.6-95.2], respectively; P = 0.47. Hypothesis confirmation was observed in 107/120 (89.2%) of noninferiority and 64/120 (53.3%) of superiority trials, risk difference (95% confidence interval): 35.8 (25.3-46.3), P < 0.001.

CONCLUSION

Protocol adherence rates are similar between superiority and noninferiority trials published in three high impact medical journals. Despite this, we observed greater hypothesis confirmation among noninferiority trials. We speculate that publication bias, lenient noninferiority margins and other sources of bias may contribute to this finding. Further study is needed to identify the reasons for this observed difference.

Clinical trials in the time of a pandemic

The first rumblings about a new coronavirus spreading in China were heard in January 2020. By the end of that month, the World Health Organization, recognizing the severity of the disease and the potential for global spread, had declared a public health emergency. By February 2020, cases had been identified in multiple countries, clinical trials of treatments with some biological plausibility had begun in China, and the initial steps of vaccine development were underway. In mid-March, by which time countries around the world were experiencing rapidly increasing numbers of cases and deaths, the World Health Organization categorized the outbreak as a pandemic. This new coronavirus was designated SARS-COV-2 in recognition of its similarity to the coronavirus responsible for the severe acute respiratory syndrome outbreak in 2002–2003. The race is on to develop treatments that can mitigate the severe consequences of infection and vaccines that can prevent infection and/or diminish the severity of disease in those who do get infected. Many challenges face these development efforts. Some are similar to those faced in the past; others are new. The urgency of finding ways to treat, and ultimately prevent, the consequences of this new and potentially deadly infection has led to unprecedented focus on clinical trials.

Biomarkers and Noncalcified Coronary Artery Plaque Progression in Older Men Treated With Testosterone

OBJECTIVE

Recent results from the Cardiovascular Trial of the Testosterone Trials showed that testosterone treatment of older men with low testosterone was associated with greater progression of noncalcified plaque (NCP). We evaluated the effect of anthropometric measures and cardiovascular biomarkers on plaque progression in individuals in the Testosterone Trial.

METHODS

The Cardiovascular part of the trial included 170 men aged 65 years or older with low testosterone. Participants received testosterone gel or placebo gel for 12 months. The primary outcome was change in NCP volume from baseline to 12 months, as determined by coronary computed tomography angiography (CCTA). We assayed several markers of cardiovascular risk and analyzed each marker individually in a model as predictive variables and change in NCP as the dependent variable.

RESULTS

Of 170 enrollees, 138 (73 testosterone, 65 placebo) completed the study and were available for the primary analysis. Of 10 markers evaluated, none showed a significant association with the change in NCP volume, but a significant interaction between treatment assignment and waist-hip ratio (WHR) (P = 0.0014) indicated that this variable impacted the testosterone effect on NCP volume. The statistical model indicated that for every 0.1 change in the WHR, the testosterone-induced 12-month change in NCP volume increased by 26.96 mm3 (95% confidence interval, 7.72-46.20).

CONCLUSION

Among older men with low testosterone treated for 1 year, greater WHR was associated with greater NCP progression, as measured by CCTA. Other biomarkers and anthropometric measures did not show statistically significant association with plaque progression.

Presenting Risks and Benefits: Helping the Data Monitoring Committee Do Its Job

Data monitoring committees (DMCs), or data and safety monitoring boards, protect clinical trial participants by conducting benefit-risk assessments during the course of a clinical trial. These evaluations may be improved by broader access to data and more effective analyses and presentation. Data monitoring committees should have access to all data, including efficacy data, at each interim review. The DMC reports should include graphical presentations that summarize benefits and harms in efficient ways. Benefit-risk assessments should include summaries that are consistent with the intention-to-treat principle and have a pragmatic focus. This article provides examples of graphical summaries that integrate benefits and harms, and proposes that such summaries become standard in DMC reports.

Prostate-Specific Antigen Levels During Testosterone Treatment of Hypogonadal Older Men: Data from a Controlled Trial

CONTEXT

Prostate-specific antigen (PSA) changes during testosterone treatment of older hypogonadal men have not been rigorously evaluated.

DESIGN

Double-blinded, placebo-controlled trial.

SETTING

Twelve US academic medical centers.

PARTICIPANTS

Seven hundred ninety hypogonadal men ≥65 years of age with average testosterone levels ≤275 ng/dL. Men at high risk for prostate cancer were excluded.

INTERVENTIONS

Testosterone or placebo gel for 12 months.

MAIN OUTCOMES

Percentile changes in PSA during testosterone treatment of 12 months.

RESULTS

Testosterone treatment that increased testosterone levels from 232 ± 63 ng/dL to midnormal was associated with a small but substantially greater increase (P < 0.001) in PSA levels than placebo treatment. Serum PSA levels increased from 1.14 ± 0.86 ng/mL (mean ± SD) at baseline by 0.47 ± 1.1 ng/mL at 12 months in the testosterone group and from 1.25 ± 0.86 ng/mL by 0.06 ± 0.72 ng/mL in the placebo group. Five percent of men treated with testosterone had an increase ≥1.7 ng/mL and 2.5% of men had an increase of ≥3.4 ng/mL. A confirmed absolute PSA >4.0 ng/mL at 12 months was observed in 1.9% of men in the testosterone group and 0.3% in the placebo group. Four men were diagnosed with prostate cancer; two were Gleason 8.

CONCLUSIONS

When hypogonadal older men with normal baseline PSA are treated with testosterone, 5% had an increase in PSA ≥1.7 ng/mL, and 2.5% had an increase ≥3.4 ng/mL.

Rigorous Clinical Trial Design in Public Health Emergencies Is Essential

Randomized clinical trials are the most reliable approaches to evaluating the effects of new treatments and vaccines. During the 2014-2015 West African Ebola epidemic, many argued that such trials were neither ethical nor feasible in an environment of limited health infrastructure and severe disease with a high fatality rate. Consensus among the numerous organizations providing help to the affected areas was never achieved, resulting in fragmented collaboration, delayed study initiation, and ultimately failure to provide definitive evidence on the efficacy of treatments and vaccines. Randomized trials were in fact approved by local ethics boards and initiated, demonstrating that randomized trials, even in such difficult circumstances, are feasible. Improved planning and collaboration among research and humanitarian organizations, and affected communities, in the interepidemic periods are needed to ensure that questions regarding the efficacy of vaccines and treatments can be definitively answered during future public health emergencies.

Sorafenib in Hepatopulmonary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial

The tyrosine kinase inhibitor sorafenib improves hepatopulmonary syndrome (HPS) in an experimental model. However, the efficacy and adverse effect profile in patients with HPS are unknown. We aimed to determine the effect of sorafenib on the alveolar-arterial oxygen gradient (AaPO₂ ) at 3 months in patients with HPS. We performed a randomized, double-blind, placebo-controlled parallel trial of sorafenib in patients with HPS at 7 centers. A total of 28 patients with HPS were randomized to sorafenib 400 mg by mouth daily or a matching placebo in a 1:1 ratio. We found no statistically significant difference in the median change in AaPO₂ from baseline to 12 weeks between the patients allocated to sorafenib (4.5 mm Hg; IQR, -3.8 to 7.0 mm Hg) and those allocated to placebo (-2.4 mm Hg; IQR, -4.8 to 8.2 mm Hg; P = 0.70). There was also no difference between the groups in terms of degree of intrapulmonary shunting by contrast echocardiography. Sorafenib significantly reduced circulating levels of angiogenic markers, including vascular endothelial growth factor receptors (P < 0.01) and TIE2-expressing M2 monocytes (P = 0.03), but it reduced the mental component scores of the Short Form 36 (P = 0.04), indicating a worse quality of life. In conclusion, sorafenib did not change the AaPO₂ or other disease markers at 3 months in patients with HPS. Alternative antiangiogenic therapies or treatments targeting other pathways should be investigated.

The TiME Trial: A Fully Embedded, Cluster-Randomized, Pragmatic Trial of Hemodialysis Session Duration

BACKGROUND

Data from clinical trials to inform practice in maintenance hemodialysis are limited. Incorporating randomized trials into dialysis clinical care delivery should help generate practice-guiding evidence, but the feasibility of this approach has not been established.

METHODS

To develop approaches for embedding trials into routine delivery of maintenance hemodialysis, we performed a cluster-randomized, pragmatic trial demonstration project, the Time to Reduce Mortality in ESRD (TiME) trial, evaluating effects of session duration on mortality (primary outcome) and hospitalization rate. Dialysis facilities randomized to the intervention adopted a default session duration ≥4.25 hours (255 minutes) for incident patients; those randomized to usual care had no trial-driven approach to session duration. Implementation was highly centralized, with no on-site research personnel and complete reliance on clinically acquired data. We used multiple strategies to engage facility personnel and participating patients.

RESULTS

The trial enrolled 7035 incident patients from 266 dialysis units. We discontinued the trial at a median follow-up of 1.1 years because of an inadequate between-group difference in session duration. For the primary analysis population (participants with estimated body water ≤42.5 L), mean session duration was 216 minutes for the intervention group and 207 minutes for the usual care group. We found no reduction in mortality or hospitalization rate for the intervention versus usual care.

CONCLUSIONS

Although a highly pragmatic design allowed efficient enrollment, data acquisition, and monitoring, intervention uptake was insufficient to determine whether longer hemodialysis sessions improve outcomes. More effective strategies for engaging clinical personnel and patients are likely required to evaluate clinical trial interventions that are fully embedded in care delivery.

Development and psychometric testing of the Canine Owner-Reported Quality of Life questionnaire, an instrument designed to measure quality of life in dogs with cancer

OBJECTIVE To describe development and initial psychometric testing of an owner-reported questionnaire designed to standardize measurement of general quality of life (QOL) in dogs with cancer. DESIGN Key-informant interviews, questionnaire development, and field trial. SAMPLE Owners of 25 dogs with cancer for item development and pretesting and owners of 90 dogs with cancer for reliability and validity testing. PROCEDURES Standard methods for development and testing of questionnaire instruments intended to measure subjective states were used. Items were generated, selected, scaled, and pretested for content, meaning, and readability. Response items were evaluated with exploratory factor analysis and by assessing internal consistency (Cronbach α) and convergence with global QOL as determined with a visual analog scale. Preliminary tests of stability and responsiveness were performed. RESULTS The final questionnaire-which was named the Canine Owner-Reported Quality of Life (CORQ) questionnaire-contained 17 items related to observable behaviors commonly used by owners to evaluate QOL in their dogs. Several items pertaining to physical symptoms performed poorly and were omitted. The 17 items were assigned to 4 factors-vitality, companionship, pain, and mobility-on the basis of the items they contained. The CORQ questionnaire and its factors had high internal consistency (Cronbach α = 0.68 to 0.90) and moderate to strong correlations (r = 0.49 to 0.71) with global QOL as measured on a visual analog scale. Preliminary testing indicated good test-retest reliability and responsiveness to improvements in overall QOL. CONCLUSIONS AND CLINICAL RELEVANCE The CORQ questionnaire was a valid, reliable owner-reported questionnaire that measured general QOL in dogs with cancer and showed promise as a clinical trial outcome measure for quantifying changes in individual dog QOL occurring in response to cancer treatment and progression.

Effect of testosterone replacement on measures of mobility in older men with mobility limitation and low testosterone concentrations: secondary analyses of the Testosterone Trials

BACKGROUND

The Physical Function Trial (PFT) was one of seven Testosterone Trials (TTrials), the aim of which was to assess the effect of testosterone on mobility, self-reported physical function, falls, and patient global impression-of-change (PGIC) in older men with low testosterone concentrations, self-reported mobility limitation, and walking speed of less than 1·2 m/s. Using data from the PFT and the overall TTrials study population, we also aimed to identify whether the effect of testosterone on mobility differed according to baseline walking speed, mobility limitation, or other participant-level factors.

METHODS

The TTrials included 790 men aged 65 years or older and with an average of two total testosterone concentrations below 275 ng/dL (9·5 nmol/L), of whom 390 had mobility limitation and a walking speed below 1·2 m/s and were enrolled in the PFT. Participants were assigned (by minimisation method) to 1% testosterone gel or placebo gel daily for 12 months, with participants and study staff masked to intervention allocation. The primary outcome of the PFT was an increase in 6 min walk test (6MWT) distance of 50 m or more. Here we report data for absolute change in 6MWT distance and physical component of Short Form-36 (PF10), and for PGIC and falls. Data are reported for men enrolled in the PFT and those who were not, and for all men in TTrials; data are also reported according to baseline walking speed and mobility limitation. Analyses were done in a modified intention-to-treat population in all patients who were allocated to treatment, had a baseline assessment, and at least one post-intervention assessment. The TTrials are registered with ClinicalTrials.gov, number NCT00799617.

FINDINGS

The TTrials took place between April 28, 2011 and June 16, 2014. Of 790 TTrials participants, 395 were allocated to testosterone and 395 to placebo; of the 390 participants enrolled in the PFT, 193 were allocated to testosterone and 197 to placebo. As reported previously, 6MWT distance improved significantly more in the testosterone than in the placebo group among all men in the TTrials, but not in those who were enrolled in the PFT; among TTrials participants not enrolled in the PFT, 6MWT distance improved with a treatment effect of 8·9 m (95% CI 2·2-15·6; p=0·010). As reported previously, PF10 improved more in the testosterone group than in the placebo group in all men in TTrials and in men enrolled in the PFT; among those not enrolled in the PFT, PF10 improved with an effect size of 4·0 (1·5-6·5; p=0·0019). Testosterone-treated men with baseline walking speed of 1·2 m/s or higher had significantly greater improvements in 6MWT distance (treatment effect 14·2 m, 6·5-21·9; p=0·0004) and PF10 (4·9, 2·2-7·7; p=0·0005) than placebo-treated men. Testosterone-treated men reporting mobility limitation showed significantly more improvement in 6MWT distance (7·6 m, 1·0-14·1; p=0·0237) and PF10 (3·6, 1·3-5·9; p=0·0018) than placebo-treated men. Men in the testosterone group were more likely to perceive improvement in their walking ability (PGIC) than men in the placebo group, both for men enrolled in the PFT (effect size 2·21, 1·35-3·63; p=0·0018) and those not enrolled in the PFT (3·01, 1·61-5·63; p=0·0006). Changes in 6MWT distance were significantly associated with changes in testosterone, free testosterone, dihydrotestosterone, and haemoglobin concentrations. Fall frequency during the intervention period was identical in the two treatment groups of the TTrials (103 [27%] of 380 analysed in both groups had at least one fall).

INTERPRETATION

Testosterone therapy consistently improved self-reported walking ability, modestly improved 6MWT distance (across all TTtrials participants), but did not affect falls. The effect of testosterone on mobility measures were related to baseline gait speed and self-reported mobility limitation, and changes in testosterone and haemoglobin concentrations.

FUNDING

US National Institute on Aging and AbbVie.

Lessons From the Testosterone Trials

The Testosterone Trials (TTrials) were a coordinated set of seven placebo-controlled, double-blind trials in 788 men with a mean age of 72 years to determine the efficacy of increasing the testosterone levels of older men with low testosterone. Testosterone treatment increased the median testosterone level from unequivocally low at baseline to midnormal for young men after 3 months and maintained that level until month 12. In the Sexual Function Trial, testosterone increased sexual activity, sexual desire, and erectile function. In the Physical Function Trial, testosterone did not increase the distance walked in 6 minutes in men whose walk speed was slow; however, in all TTrial participants, testosterone did increase the distance walked. In the Vitality Trial, testosterone did not increase energy but slightly improved mood and depressive symptoms. In the Cognitive Function Trial, testosterone did not improve cognitive function. In the Anemia Trial, testosterone increased hemoglobin in both men who had anemia of a known cause and in men with unexplained anemia. In the Bone Trial, testosterone increased volumetric bone mineral density and the estimated strength of the spine and hip. In the Cardiovascular Trial, testosterone increased the coronary artery noncalcified plaque volume as assessed using computed tomographic angiography. Although testosterone was not associated with more cardiovascular or prostate adverse events than placebo, a trial of a much larger number of men for a much longer period would be necessary to determine whether testosterone increases cardiovascular or prostate risk.