Role of Hospital and Physician Volume in Outcome Disparity Among Elderly Prostate Cancer Patients

Objective: To analyze the role of hospital and physician volume in the racial and ethnic disparity in outcomes among prostate cancer (PCa) patients after controlling for stage, comorbidity, socioeconomic status (SES) and clinical characteristics.

Methods: Retrospective case-control design using SEER-Medicare databases. Prostate cancer patients diagnosed between 1995 and 1998 were identified and retrospectively followed for one year pre and five years post-diagnosis. Hospitals with more than 60 cases per year were defined as ‘high' volume. Physicians with greater than 40 cases per year were considered as ‘high' volume. For each racial and ethnic group, we fitted separate survival models to analyze the association between physician and hospital volume and mortality, after adjusting for Elixahuser comorbidity, SES and stage. We fitted GLM log-link models to study the association between physician and hospital volume and cost.

Results: We identified 40,876 Caucasians, 5,867 African Americans and 3,034 Hispanics newly diagnosed for PCa between 1995 and 1998. Survival models indicated that for African American and Caucasian patients, high hospital volume was associated with lower mortality (HR=0.75, p<.0001; HR=0.74, p=.0004, respectively). Physician volume was not associated with mortality for any group. An inverse association between hospital volume and cost was observed -higher hospital volume meant lower cost for all groups. No association was observed between physician volume and cost for any of the groups.

Conclusions: Hospital volume, but not physician volume, appears to be associated with outcomes across the different racial/ethnic groups. Thus, the role of hospital volume in disparity in outcomes needs further exploration.