Screening Mammography in Women Aged 70 to 79 Years

CLINICAL QUESTION: Is screening mammography in women aged 70 to 79 years beneficial?

BACKGROUND: There is limited direct evidence either for or against screening mammography in elderly women. This analysis had 2 purposes: estimate the effects of continued screening in women aged 70 to 79 years and predict whether it may be more cost-effective to screen only women with higher bone mineral density (BMD) because of their greater risk of developing breast cancer. population studied n The authors included a hypothetical cohort of 10,000 healthy women, all of whom had BMD testing at age 65 and biennial screening mammography until age 69.

STUDY DESIGN AND VALIDITY: This decision and cost-effectiveness analysis compared 3 strategies: (1) discontinue screening mammography after age 69; (2) continue biennial screening until age 79 years only for women whose distal radial BMD is in the top 3 quartiles (check BMD strategy); and (3) continue biennial screening for all women to age 79. The primary analysis included costs for screening mammography ($116), working-up abnormal mammograms, and treating invasive breast cancer and ductal carcinoma in situ, but not for the BMD test. Probabilities included age-adjusted breast cancer incidence and 10-year mortality rates, all-cause mortality rate, percentage of mortality reduction from screening (27%), abnormal mammogram rate, and the breast cancer risk associated with different BMD quartiles. Costs and health benefits were discounted 3% in the primary analysis. One-way sensitivity analyses were conducted for quality-adjusted life after diagnosis of breast cancer, discount rates, BMD test cost, mortality reduction from mammography, 10-year breast cancer mortality rate, and breast cancer risk reduction associated with low BMD.

An appropriately comprehensive spectrum of direct costs and effects were included and based on actual data when possible.¹ The effect of screening mammography on breast cancer mortality reduction was taken from a meta-analysis of women aged 50 to 74 years. Neither indirect costs nor the disutility of having a mammogram were included, and sensitivity analyses were not performed for costs other than for the BMD tests. The analysis did not include other strategies, such as annual mammography or using other clinical information to stratify women who might benefit more (eg, with the presence of other risk factors for breast cancer) or less (eg, presence of comorbidities) from screening.

OUTCOMES MEASURED: The authors measured the number of deaths due to breast cancer averted, average increase in overall and quality-adjusted life expectancy, and cost per year of life saved (YLS) and quality-adjusted life year (QALY) saved.

RESULTS: Compared with discontinuing mammography at age 69 years, continued biennial screening in women with BMD in the top 3 quartiles would prevent 9.4 deaths (number needed to screen [NNS]=1064) and add an average 2.1 days to life expectancy at an incremental cost of $67,000 per year of life saved. Compared with the check BMD strategy, continued biennial mammography in all 10,000 women would prevent an additional 1.4 deaths (NNS=7143) and add only 0.3 days of life expectancy at an incremental cost of $118,000 per year of life saved. If a woman’s life utility is 0.8 after being diagnosed with treatable breast cancer, the cost per QALY saved in the check BMD strategy is $1,200,000, and the strategy of screening all women is more harmful because it leads to an incremental decrease in average life expectancy of 0.2 days. The analysis was also sensitive to discount rates (eg, for a discount rate of 15% the cost per YLS in the check BMD strategy is $313,000). Finally, if the cost of the BMD test ($50) is included, the strategies of check BMD and screen all women are equally cost-effective ($75,000 per YLS).