Multilevel factors associated with long-term adherence to screening mammography in older women in the U.S.

In the U.S., guidelines recommend that women continue mammography screening until at least age 74, but recent evidence suggests declining screening rates in older women. We estimated adherence to screening mammography and multilevel factors associated with adherence in a longitudinal cohort of older women. Women aged 66-75years receiving screening mammography within the Breast Cancer Surveillance Consortium were linked to Medicare claims (2005-2010). Claims data identified baseline adherence, defined as receiving subsequent mammography within approximately 2years, and length of time adherent to guidelines. Characteristics associated with adherence were investigated using logistic and Cox proportional hazards regression models. Analyses were stratified by age to investigate variation in relationships between patient factors and adherence. Among 49,775 women, 89% were adherent at baseline. Among women 66-70years, those with less than a high school education were more likely to be non-adherent at baseline (odds ratio [OR] 1.96; 95% confidence interval [CI] 1.65-2.33) and remain adherent for less time (hazard ratio [HR] 1.41; 95% CI 1.11-1.80) compared to women with a college degree. Women with ≥1 versus no Charlson co-morbidities were more likely to be non-adherent at baseline (OR 1.46; 95% CI 1.31-1.62) and remain adherent for less time (HR 1.44; 95% CI 1.24-1.66). Women aged 71-75 had lower adherence overall, but factors associated with non-adherence were similar. In summary, adherence to guidelines is high among Medicare-enrolled women in the U.S. receiving screening mammography. Efforts are needed to ensure that vulnerable populations attain these same high levels of adherence.