Background/Aims Testosterone replacement therapy is a widespread and growing practice for treating androgen deficiency. Characteristics of males receiving testosterone and treatment patterns in a managed care setting are relatively unexplored. The purpose of this study was to describe the characteristics and treatment patterns of males receiving testosterone therapy.

Methods We identified patients who received a testosterone prescription from January 1999 to December 2010 in Kaiser Permanente Southern California (KPSC). We excluded patients receiving testosterone therapy for indications other than androgen deficiency, including: 1) age <30, 2) genetic indications, 3) hypothalamic or pituitary dysfunction, and 4) testicular or pituitary trauma. Twelve months continuous membership prior to the index date was required for inclusion in the cohort. We investigated demographics, testosterone prescriptions, baseline diagnoses, total serum testosterone laboratory results, and physician specialty. Descriptive statistics and paired t-test were used.

Results Among testosterone users (N = 10,159) the mean (SD) age was 56.8 (11.6) and 67.7% were white. On an annual basis, from 1999 to 2010, the treatment rate increased by 183% and number of prescriptions per patient increased by 22%. The most frequently prescribed testosterone products were transdermal gels (55.7%), patches (26.2%), and intramuscular injections (14.4%). The average duration of exposure was close to one year [mean (SD) days supply = 320.0 (504.2) days]. Baseline testosterone levels were obtained in 91.0% of patients and the mean (SD) serum testosterone level was 259.7 (179.5) ng/dL. Follow-up testosterone levels were drawn in 59.8% of patients within one year of the index date and the mean (SD) serum testosterone level was 395.0 (275.3) ng/dL. The mean increase from the baseline was 151.9 (95% CI = 160.5, 143.3) for transdermal gels, 118.0 (129.5, 106.5) for patches, and 200.7 (237.0, 164.3) for intramuscular injections. The most frequent diagnoses at baseline were hypertension (43.7%), hyperlipidemia (43.1%), erectile dysfunction (33.5%), testicular dysfunction (26.7%), and diabetes (20.3%). Testosterone prescriptions were most frequently written by primary care providers (family practice [36.0%] or internal medicine [20.1%]) followed by specialists (endocrinology [13.5%] and urology [6.6%]).

Conclusions Testosterone therapy is rapidly increasing treatment among aging males in KPSC, and most frequently prescribed by primary care physicians.