In this analysis of prostatectomy for localized prostate cancer among elderly black and white men, we found that 40.1% of patients had a different diagnosing and treating urologist. Black men were less likely to undergo prostatectomy by a high-volume urologist than white men, and this disparity is largely attributable to lower rates of changing from a low-volume urologist at diagnosis to a high-volume urologist for treatment. To our knowledge, this is the first study to demonstrate that racial differences in treatment by a high-volume surgeon can be attributed to differences in the probability of changing surgeons. These results have important implications for efforts to address racial disparities in treatment by high-volume surgeons.
Currently very little is known about what drives the selection of a surgeon or movement from a low-volume to a high-volume surgeon for treatment. Prior research has tended to focus on why patients change their primary care providers.23-30
Trust and satisfaction have been shown to be important predictors of changing one's usual source of care,23-26,28-30
though these may have different meanings and be given different importance in the context of surgeon selection. Katz and colleagues found that women with breast cancer who chose their surgeon based on reputation were more likely to be treated by a high-volume surgeon compared to women who were referred or who chose based on proximity.31
Though surgeon volume may be correlated with reputation, it is uncertain whether patients and their referring doctors are directly aware of surgeon volume and how it factors into their decision-making relative to other attributes of the surgeon and his/her practice.32,33
Additionally, travel distance and the spatial distribution of high-volume urologists are likely important factors in surgeon selection.8,34,35
Evidence suggests that with the increasing centralization of prostate cancer surgery at high-volume hospitals, travel distances for patients have increased over time.35
While we did not directly assess the factors that determine racial differences in changing urologists, our results suggest that these differences arise both because of racial differences in which low-volume urologist black and white patients see at the time of diagnosis (between-doctor effects) and because of racial differences in changing from the same diagnosing urologist (within-doctor effects). The finding that black and white patients tended to be diagnosed by different low-volume urologists is not surprising given the considerable evidence supporting racial differences in providers in many other settings. High levels of segregation have been documented in the health care system, including primary and hospital care.36,37
Furthermore, providers who care for greater proportions of minority patients have been found to have different access to institutional resources and different quality and patient outcomes.38-40
Here, diagnosing urologists who treat a greater proportion of black patients are less likely to have their patients change to a high-volume urologist than diagnosing urologists who care for a smaller proportion of black patients. This difference occurs even though these urologists do not differ in surgical volume themselves and the patients all have the same insurance. While it is interesting to speculate that this pattern may be driven by factors such as practice structure (e.g. solo versus group), strength of hospital affiliation, or spatial distribution of providers with respect to where patients live, further research is needed to understand the factors underlying this variation.
Our results further suggest that black and white patients who are diagnosed by the same urologist have different rates of changing to high-volume surgeons. This pattern may relate to diagnosing urologists making different recommendations about referral for their black and white patients. Using clinical vignettes, Denberg and colleagues found that urologists gave different recommendations regarding prostate cancer treatment for patients of different races and social vulnerability.41
Differences in recommendations by patient race may stem from a variety of factors including physician-bias, heuristics or clinical uncertainty.42,43
Alternatively, patient decision-making and preferences may also drive the observed patterns of changing urologists.44
It is possible that differences in doctor-patient communication,45,46
access to care,49
access to new technology (e.g. robotic prostatectomy),50
and ability to travel (e.g. financial, time, and psychological costs)34
may be important determinants of patient decisions to change urologists and may vary by race.
Black men were significantly less likely to be diagnosed by a high-volume urologist; however, this association was largely explained by other factors. In particular, diagnosis by a high-volume urologist was significantly associated with residing in a higher income areas. Higher area income was also strongly associated with changing from a low- to a high-volume urologist. Area-level income may correlate with the local availability of high-volume urologists and be a proxy for patient-level factors (e.g. economic resources, self-efficacy, and literacy) that may predispose individuals to receive their diagnosis and treatment from high-volume providers. It is possible that academic medical centers, which are frequently located in low-income, inner-city areas, may serve to mitigate these racial and socioeconomic disparities.51,52
The results of this study need to be considered in light of its limitations. First, prostatectomy volume is based on SEER-Medicare claims and has the potential for misclassification error. Medicare volume has been shown to accurately reflect total urologist prostatectomy volume, 2
but it is possible that patients traveling outside of a SEER site to receive treatment might lead to that treating urologist being inaccurately classified as low-volume as patients from outside of the SEER site are not captured. Second, our matching of patients to their diagnosing and treating physicians is incomplete. Third, the definition of the diagnosing urologist is based on claims data rather than patient-report and has the potential for misclassification error. Fourth, we are unable to account for practice structure that may affect both the rates of provider changing and decisions about which specific doctor to see. Fifth, though we use average patient volume over the years in practice in defining urologist volume, the number of cases a physician performs may vary year to year. Sensitivity analyses that defined high-volume providers as the top two quartiles of the sample distribution revealed qualitatively similar results (see Appendix Tables 2 and 3
). Sixth, we exclude men who may have been referred to a high- or low-volume treating urologist but did not undergo surgery; this may lead to biased estimates of the association between race and changing urologists. Though we are unable to observe physician recommendations in claims data, we ran additional analyses examining rates of changing doctors among all men diagnosed with localized prostate cancer regardless of treatment (see Appendix 1
for a complete description). In adjusted analyses, black patients were significantly less likely to be diagnosed by a high-volume urologist (OR 0.85, 95%CI 0.78 – 0.93) and, among those diagnosed by a low-volume urologist, less likely to change to a high-volume urologist for their follow-up care. The results support our main findings. Finally, relying on urologist volume as the sole marker of quality has potential limitations, and disparities in recurrence-free survival and mortality persisted among black and white men who received their prostatectomy from medium and high-volume urologists and hospitals.3
The current study demonstrates high rates of changing urologists between diagnosis and surgical treatment. However, black men were significantly less likely to change overall and less likely to change to a high-volume urologist for their surgical treatment. The potential benefits of receiving care from high-volume urologists may be substantial—for example, compared to low-volume urologists, high-volume urologists tend to have fewer in-hospital (12% versus 22%)12
and late urinary complications (20 versus 28%),11
and longer time to recurrence (73 versus 60 months for the 25th
However, in order to realize these benefits, interventions that attempt to reduce disparities in access to high-volume surgeons will require a deeper understanding of the specific pathways through which patients come to receive surgical care. Particular attention should be paid to disentangling the patient-, physician- and system-level factors that may impede black and low-income patients from changing urologists. To the extent that patient choice drives surgeon selection, then patients will need to be educated about the importance of asking about surgical volume. Awareness campaigns may also need to target referring physicians, and systemic-barriers (e.g. differential institutional resources, uneven spatial distribution of providers, barriers to patient-travel) may need to be addressed in order to mitigate these disparities.