Disparities in Stage at Diagnosis in an Equal-access Integrated Delivery System: A Retrospective Cohort Study of 7244 Patients With Bladder Cancer

Abstract

Background: Disparities in bladder cancer survival by race/ethnicity and gender are likely related to differences in diagnosis. We assessed disparities in stage at diagnosis and potential contributing factors within a large, integrated delivery system.

Patients and methods: We conducted a retrospective cohort study of 7244 patients with bladder cancer age ≥ 21 years diagnosed from January 2001 to June 2015 within Kaiser Permanente Southern California. Bivariate analyses compared stage at diagnosis - as well as comorbidities, health plan membership length, and health care utilization prior to diagnosis - by race/ethnicity, gender, and age. Multivariable generalized linear mixed models with urologist as a random effect were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for diagnosis of muscle-invasive bladder cancer (MIBC) versus non-muscle-invasive bladder cancer.

Results: In multivariable analyses, stage at diagnosis varied significantly by race/ethnicity (P < .001). Non-Hispanic black patients had significantly higher odds of being diagnosed with MIBC than non-Hispanic white patients (OR, 1.33; 95% CI, 1.05-1.67), whereas Asian patients had significantly lower odds (OR, 0.67; 95% CI, 0.49-0.91). Women were significantly more likely to be diagnosed with MIBC than men (OR, 1.40; 95% CI, 1.22-1.61). Non-Hispanic black women had the highest proportion (39%) of MIBC diagnoses. Among Hispanic and Asian patients, a greater proportion of diagnoses occurred at younger ages.

Conclusions: Health care coverage within an equal-access system did not eliminate disparities in stage at diagnosis by race/ethnicity or gender. Studies are needed to identify etiologic factors and aspects of care delivery (eg, patient-physician interactions) that may affect the diagnostic process to inform efforts to improve health equity.

Keywords: Age; Gender; Health status disparities; Race/ethnicity; Urinary bladder neoplasms.