Background: U.S. women of ages 50-74 years are recommended to receive screening mammography at least biennially. Our objective was to evaluate multilevel predictors of nonadherence among screened women, as these are not well known. Materials and Methods: A cohort study was conducted among women of ages 50-74 years with a screening mammogram in 2011 with a negative finding (Breast Imaging-Reporting and Data System 1 or 2) within Population-based Research Optimizing Screening through Personalized Regimens (PROSPR) consortium research centers. We evaluated the association between woman-level factors, radiology facility, and PROSPR research center, and nonadherence to breast cancer screening guidelines, defined as not receiving breast imaging within 27 months of an index screening mammogram. Multilevel mixed-effects logistic regression was used to calculate odds ratios and 95% confidence intervals. Results: Nonadherence to guideline-recommended screening interval was 15.5% among 51,241 women with a screening mammogram. Non-Hispanic Asian/Pacific Islander women, women of other races, heavier women, and women of ages 50-59 years had a greater odds of nonadherence. There was no association with ZIP code median income. Nonadherence varied by research center and radiology facility (variance = 0.10, standard error = 0.03). Adjusted radiology facility nonadherence rates ranged from 10.0% to 26.5%. One research center evaluated radiology facility communication practices for screening reminders and scheduling, but these were not associated with nonadherence. Conclusions: Breast cancer screening interval nonadherence rates in screened women varied across radiology facilities even after adjustment for woman-level characteristics and research center. Future studies should investigate other characteristics of facilities, practices, and health systems to determine factors integral to increasing continued adherence to breast cancer screening.
Keywords: breast cancer; guideline adherence; mammography; screening.