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In any clinical trial, it is essential to monitor the accumulating data to be sure that the trial continues to be safe for participants and that the trial is being conducted properly. Data monitoring committees, independent expert panels who undertake regular reviews of the data as the trial progresses, serve an important role in safeguarding the interests of research participants and ensuring trial integrity in many trials. Many pragmatic clinical trials, which aim to inform healthcare decisions by comparing alternate interventions in heterogeneous healthcare delivery settings, will warrant review by an independent data monitoring committee due to their potential impact on clinical practice. However, the very features that make a trial "pragmatic" may pose challenges in terms of which aspects of a trial to monitor and when it is appropriate for a data monitoring committee to intervene. Using the Pragmatic-Explanatory Continuum Indicator Summary tool that draws distinctions between pragmatic and explanatory clinical trials, we review characteristics of pragmatic clinical trials that may have implications for data monitoring committees and interim monitoring plans. These include broad eligibility criteria, a focus on subjective patient-centered outcomes, and in some cases a lack of standardized follow-up procedures across study sites. Additionally, protocol adherence is often purposefully not addressed in pragmatic trials in order to accurately represent the clinical practice setting and maintain practicability of implementation; there are differing viewpoints as to whether adherence should be assessed and acted upon by data monitoring committees in these trials. Some other issues not specifically related to the Pragmatic-Explanatory Continuum Indicator Summary criteria may also merit special consideration in pragmatic trials. Thresholds for early termination of a pragmatic clinical trial might be controversial. The distinguishing features of pragmatic clinical trials require careful consideration when developing interim data monitoring plans, and trial sponsors, investigators, and data monitoring committees should agree on a plan before trial inception. Finally, special expertise, such as an informatics, may be helpful on data monitoring committees for some pragmatic clinical trials. Patient representatives may provide particularly valuable insights in the monitoring process.

Background The prevalence of low testosterone levels in men increases with age, as does the prevalence of decreased mobility, sexual function, self-perceived vitality, cognitive abilities, bone mineral density, and glucose tolerance, and of increased anemia and coronary artery disease. Similar changes occur in men who have low serum testosterone concentrations due to known pituitary or testicular disease, and testosterone treatment improves the abnormalities. Prior studies of the effect of testosterone treatment in elderly men, however, have produced equivocal results. Purpose To describe a coordinated set of clinical trials designed to avoid the pitfalls of prior studies and to determine definitively whether testosterone treatment of elderly men with low testosterone is efficacious in improving symptoms and objective measures of age-associated conditions. Methods We present the scientific and clinical rationale for the decisions made in the design of this set of trials. Results We designed The Testosterone Trials as a coordinated set of seven trials to determine if testosterone treatment of elderly men with low serum testosterone concentrations and symptoms and objective evidence of impaired mobility and/or diminished libido and/or reduced vitality would be efficacious in improving mobility (Physical Function Trial), sexual function (Sexual Function Trial), fatigue (Vitality Trial), cognitive function (Cognitive Function Trial), hemoglobin (Anemia Trial), bone density (Bone Trial), and coronary artery plaque volume (Cardiovascular Trial). The scientific advantages of this coordination were common eligibility criteria, common approaches to treatment and monitoring, and the ability to pool safety data. The logistical advantages were a single steering committee, data coordinating center and data and safety monitoring board, the same clinical trial sites, and the possibility of men participating in multiple trials. The major consideration in participant selection was setting the eligibility criterion for serum testosterone low enough to ensure that the men were unequivocally testosterone deficient, but not so low as to preclude sufficient enrollment or eventual generalizability of the results. The major considerations in choosing primary outcomes for each trial were identifying those of the highest clinical importance and identifying the minimum clinically important differences between treatment arms for sample size estimation. Potential limitations Setting the serum testosterone concentration sufficiently low to ensure that most men would be unequivocally testosterone deficient, as well as many other entry criteria, resulted in screening approximately 30 men in person to randomize one participant. Conclusion Designing The Testosterone Trials as a coordinated set of seven trials afforded many important scientific and logistical advantages but required an intensive recruitment and screening effort.