We describe the recruitment of men for The Testosterone (T) Trials, which were designed to determine the efficacy of T treatment.

Men were eligible if they were ≥65 years, had an average of two morning total T values <275ng/dL with neither value >300ng/mL, and had symptoms and objective evidence of mobility limitation, sexual dysfunction, and/or low vitality. Men had to be eligible for and enroll in at least one of these three main trials (physical function, sexual function, vitality).

Men were recruited primarily through mass mailings in 12 U.S. communities: 82% of men who contacted the sites did so in response to mailings. Men who responded were screened by telephone to ascertain eligibility. Of 51,085 telephone screens, 53.5% were eligible for further screening. Of 23,889 initial screening visits (SV1), 2,781 (11.6%) men were eligible for the second screening visit (SV2), which 2,261 (81.3%) completed. At SV2, 931 (41.2%) men met the criteria for one or more trials, the T level criterion and had no other exclusions. Of these, 790 (84.6%) were randomized; 99 (12.5%) in all three trials and 348 (44%) in two trials. Their mean age was 72 years and mean body mass index (BMI) was 31.0kg/m². Mean (standard deviation) total T (ng/dL) was 212.0 (40.0).

Despite the telephone screening to enrollment ratio of 65 to 1, we met the recruitment goals for each trial. Recruitment of symptomatic older men with low testosterone levels is difficult but feasible.