Determinants of androgen deprivation therapy use for prostate cancer: Role of the urologist

Background. The use of androgen deprivation therapy for prostate cancer has been increasing, even in settings for which there is weak or no evidence of efficacy. This pattern suggests that factors other than the typical patient and tumor characteristics may be driving its use. We assessed the importance of the physician as a determinant of the use of androgen deprivation therapy in prostate cancer in a population-based, retrospective cohort study using the Surveillance, Epidemiology and End-Results-Medicare linked database. Methods: Participants included 61717 men with incident prostate cancer diagnosed from January 1, 1992, through December 31, 1999, and 1802 urologists providing care to them within I year of cancer diagnosis. Multilevel analyses were used to estimate and partition the variance in use of androgen deprivation therapy within 6 months of diagnosis between patient or tumor characteristics and urologist to examine the relative contribution of each component to androgen deprivation therapy. Results: The percentage of the total variance in the use of androgen deprivation therapy attributable to the urologist was consistently higher than that attributable to tumor or patient characteristics. This pattern was most pronounced for patients diagnosed from January 1, 1997, through December 31, 1999, in which 22.56% of the total variance in use of androgen deprivation therapy was attributable to the urologist, 9.71% to tumor characteristics (stage or grade), and 4.29% to patient characteristics (age, ethnicity, socio-economic status, comorbidity, geographic region, or year of diagnosis). Conclusions: Which urologist a patient sees may be more important in determining whether they will receive androgen deprivation therapy than tumor or patient characteristics.