Screening Mammography Program of British Columbia: pattern of use and health care system costs.

BACKGROUND: The use of mammography for screening asymptomatic women has increased dramatically in the past decade. This report describes the changes that have occurred in the use of bilateral mammography in British Columbia since the provincial breast cancer screening program began in 1988.
METHODS: Using province-wide databases from both the breast cancer screening program and the provincial health insurance plan in BC, the authors determined the number and costs of bilateral mammography services for women aged 40 years or older between Apr. 1, 1986, and Mar. 31, 1997. Unilateral mammography was excluded because it is used for investigating symptomatic disease and screening abnormalities, and for follow-up of women who have undergone mastectomy for cancer.
RESULTS: As the provincial breast cancer screening program expanded from 1 site in 1988 to 23 in 1997, it provided an increasing proportion of the bilateral mammographic examinations carried out each year in BC. In fiscal year 1996/97, 65% of bilateral mammographic examinations were performed through the screening program. The cost per examination within the screening program dropped as volume increased. Thirty percent more bilateral mammography examinations were done in 1996/97 than in 1991/92, but health care system expenditures for these services increased by only 4% during the same period. In calendar year 1996, 21% of new breast cancers were diagnosed as a result of a screening program visit.
INTERPRETATION: Substantial increases in health care expenditures have been avoided by shifting bilateral mammography services to the provincial screening program, which has a lower cost per screening visit.