To examine treatment variability, disparities, and quality among newly diagnosed nonmuscle invasive bladder cancer (NMIBC) patients, and to identify factors associated with treatment use in a large, diverse integrated delivery system.

Retrospective cohort study of 5386 NMIBC patients diagnosed between January 2001 and June 2015 within Kaiser Permanente Southern California. Electronic health data were used to identify treatment outcomes and patient, provider, and tumor characteristics. Outcomes were use of (1) postoperative intravesical chemotherapy, (2) induction Bacille Calmette-Guérin (BCG) immunotherapy, and (3) any intravesical therapy. Multivariable odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using generalized linear mixed models with a binary outcome and urologist as a random effect.

From 2001 to 2015, 41% of newly diagnosed NMIBC patients were treated with intravesical therapy. Postoperative chemotherapy use increased significantly over this period (OR per-year = 1.16, 95% CI: 1.07-1.25). BCG use was strongly associated with tumor characteristics: patients with high-grade or carcinoma in situ tumors were more likely to receive BCG (OR = 10.10, 95% CI: 8.39-12.16). Few treatment differences were found by sex or race/ethnicity, but were observed by age. Wide treatment variability across urologists was observed, with some urologists never using intravesical therapy as part of initial treatment while others almost always used it. Differences across urologists accounted for more variability in postoperative chemotherapy (intraclass correlation coefficient = 0.52) than BCG immunotherapy (intraclass correlation coefficient = 0.11) use.

Substantial variability in initial treatment of NMIBC was observed across urologists, accounting for tumor, patient, and provider characteristics. Results suggest a considerable opportunity for quality improvement programs to reduce unwanted treatment variability and improve care for patients.