Adherence to Screening Among American Indian Women Accessing a Mobile Mammography Unit

Although screening mammography is essential to reducing breast cancer morbidity and mortality, barriers exist especially among underrepresented minority groups. There are few studies of mammogram screening among American Indian women, many of whom reside in rural areas where screening access is challenging. A mobile mammography unit served 24 Indian Health Service clinics during 2013-17. Screening mammography adherence was evaluated.

Among mobile unit women, 'adherence to screening' was determined by the date of the most recent prior mammogram. Those having a prior mammogram 9-27 months ago were classified as 'adherent to screening'. Comparison screening data were obtained from the American College of Radiology National Mammography Database, consisting of screening cases occurring in year 2015. Additionally, among mobile unit women 'continued adherence to screening' was determined, defined as at least one repeat screening at the mobile unit within the subsequent 9-27 months after a screening there.

Among 1,615 mobile unit women, 624 (38.6%) were adherent to screening. Among 2,509,826 National Mammography Database women, 1,481,021 (59.0%) were adherent to screening. (p<0.0001) The prevalence of a >27-month interval between mammograms was 3.13 (95% CI 2.91-3.36) times greater among mobile unit women than National Mammography Database women. 'Continued adherence to screening' of mobile unit women was 428/1194 (35.9%).

Adherence to screening and continued adherence to screening were low among mobile unit women and time interval between screenings was longer than National Mammography Database women. Factors to improve screening adherence among these underserved women should be determined.