Background: Increased breast tissue density may mask cancer and thus decrease the diagnostic sensitivity of mammography. A patient group advocacy led to the implementation of laws to increase the awareness of breast tissue density and to improve access to supplemental imaging in many states. Given limited evidence about best practices, variation exists in several characteristics of adopted policies.
Objective: To identify which characteristics of state-level policies with regard to dense breast tissue were associated with increased use of downstream breast ultrasound.
Research design: This was a retrospective series of monthly cross-sections of screening mammography procedures before and after implementation of laws.
Subjects: A sample of 13,481,554 screening mammography procedures extracted from the MarketScan Research database performed between 2007 and 2014 on privately insured women aged 40-64 years that resided in a state that had implemented relevant legislation during that period.
Measures: The outcome was an indicator of whether breast ultrasound imaging followed a screening mammography procedure within 30 days. The main independent variables were policy characteristics indicators.
Results: Notification of patients about issues surrounding increased breast density was associated with increased follow-up by ultrasound by 1.02 percentage points (P=0.016). Some policy characteristics such as the explicit suggestion of supplemental imaging or mandated coverage of supplemental imaging by health insurance augmented that effect. Other policy characteristics moderated the effect.
Conclusions: The heterogeneous effect of state legislation with regard to dense breast tissue on screening mammography follow-up by ultrasound may be explained by specific and unique characteristics of the approaches taken by a variety of states.