Mammography in New Hampshire: characteristics of the women and the exams they receive.

New Hampshire (NH) is one of two states that has developed a population-based mammography registry. The purpose of this paper is to describe what we have learned about mammography use in New Hampshire. After collecting data for 20 months, the database contains almost 110,000 mammographic encounters representing 101,679 NH women, who range in age from 18 to 97 with a mean of 56.7 years (SD=10.91). Education levels are high with 92% having a high school education and 59% with some college. Forty-six percent report their primary insurance is private, 29% report HMO/PPO coverage, and 25% receive federal health care assistance. Risk factors represented in the database include (categories not mutually exclusive) advancing age (60% over age 50), hormone replacement therapy use by menopausal women (40.6%), and a family history of breast cancer (29%). Penetration of mammography relative to the NH population is higher for younger age groups (40-48% for those aged 44-64) than older age groups (34-39% for those aged 65-84). The majority of mammographic encounters are routine screening exams (86%), often interpreted as negative or normal with benign findings (88%). Use of comparison films to interpret either diagnostic or screening mammography occurred in 86% of encounters. We have matched 3,877 breast pathology records to these mammographic encounters. The distribution of pathology outcomes for diagnostic exams was very similar to that for screening exams (approximately 65% benign, 17% invasive breast cancer, and 6% noninvasive breast cancer). Overall, we have designed a system that is well accepted by the NH community. Challenges include careful monitoring of data for coding errors, and a limitation of linking variables in mammography and pathology data. Data represented in this registry are a critical resource for research in mammographic screening and breast cancer early detection.