Loss of QALY in mammography screening reported by Zahl et ah

摘要

Zahl et al. assumed the effect of modern screening programs to be (/) a 10% reduction in breast cancer mortality; (it) 50-75% overdiagnosis; and that {Hi) 20-80% of reduction in breast cancer mortality translate into reduction in all-cause mortality. Using 50% for the last variable, a QALY loss of 437-875 per 100,000 was expected in women screened for 20 years starring at age 50.Denmark is probably the country with the best data for estimating the effect of modern screening, because 20% of women aged 50-69 years were invited for screening during a 17 years period, whereas the other 80% of women were not invited, and opportunistic screening was rare. Register data furthermore allowed for control of prescreening regional differences. Long-term follow-up of invited compared to not-invited women showed a 20% reduction in breast cancer mortality,2 and a 5% overdiagnosis3 (recalculated to correspond to Zahl et al.'s numbers).