Impact of prior primary care utilization on limiting racial disparities for prostate cancer diagnosis and mortality.

26 Background: Black men are more likely to develop lethal prostate cancer (PCa) than non-Hispanic White men. It is not clear if this disparity is related to inherent biological causes or differences in social determinants of health including health care access and utilization. We evaluated the impact of prior primary care provider (PCP) utilization on PCa outcomes and its potential for addressing existing racial disparities. Methods: Our retrospective cohort study utilized the SEER-Medicare database and included patients diagnosed with PCa from 2010-2017. PCP visits were binned into absent (0 visits), partial (1-2 visits), and annual (3 visits). Separate multivariable logistic regression models assessed the impact of prior PCP utilization on prostate-specific antigen (PSA) > 20, Gleason score ≥ 8, and metastatic disease at diagnosis. A multivariable competing risk cox proportional hazards model evaluated the association between prediagnostic PCP visits and cause-specific mortality (CSM). Results: Among 41,063 patients, we found the following PCP utilization rates: 3,509 (8.5%) were absent, 20,618 (50.2%) were partial, and 16,936 (41.2%) were annual. Compared with absent PCP utilization, partial utilization was associated with significantly decreased odds of PSA > 20 (Odds Ratio [OR]: 0.36, 95% confidence interval [CI]: 0.33-0.40, p<0.005), Gleason score ≥ 8 (OR: 0.50, 95% CI: 0.46-0.54, p<0.005), and metastatic disease at diagnosis (OR: 0.29, 95% CI 0.26-0.33, p<0.005). Annual PCP utilization had similar directionality and effect sizes on PSA > 20 (OR: 0.35, 95% CI 0.32-0.38, p<0.005), Gleason score ≥ 8 (OR: 0.54, 95% CI 0.50-0.59, p<0.005), and metastatic disease at diagnosis (OR: 0.32, 95% CI 0.29-0.36, p<0.005). Patients with partial and annual PCP utilization had significantly lower risk of CSM when compared with patients with absent utilization (subdistribution hazard ratio (SHR) partial : 0.40, 95% CI 0.37 -0.44, p<0.005 and SHR annual : 0.43, 95% CI 0.39-0.47, p<0.005). Compared to non-Hispanic White patients, Black patients had significantly higher odds of metastatic disease at diagnosis (OR 1.25, 95% CI 1.12-1.07, p<0.005) and CSM (SHR 1.17, 95% CI 1.06-1.28, p<0.005). Adjusting for prediagnostic PCP utilization, there is no significant difference between metastatic disease at diagnosis (OR 1.10, 95% CI 0.98-1.24, p=0.11) or CSM (HR 1.08, 95% CI 0.98-1.18, p=0.13) between non-Hispanic White and Black patients. Conclusions: For patients diagnosed with PCa, higher prediagnostic PCP utilization is associated with earlier stage at diagnosis and lower risk of death from PCa. Disparities seen in metastatic disease and CSM between Black and white men were eliminated when adjusting for prediagnostic PCP utilization suggesting that increasing primary care utilization may help mitigate observed racial disparities between Black and non-Hispanic White men diagnosed with PCa.