Trends in mammography 1991-96 and the impact of nationwide screening in The Netherlands

To investigate the impact of the population based breast screening programme on total uptake of mammography in the Netherlands.

The Netherlands; breast screening programme for women aged 50-69; 21,820 women who participated in the 1991-96 Health Interview Survey (HIS).

HIS data linked to data related to the start of the screening programme in different municipalities investigating mammography use, reasons for mammography, and further assessment procedures.

Among women aged 50-69 the percentage who had recently undergone mammography (in the year of the HIS or two years before) increased from 20% in 1991 to 70% in 1996, which was entirely due to screening. The percentage of women in this age group who had had a recent clinical mammogram (outside the screening programme) varied between 8 and 12% and did not change significantly in municipalities without screening. There was no change in the uptake of mammography among women under 50 years of age. Among women over 70 there was only a small increase in this percentage from 6 to 13%, partially due to screening mammograms. In municipalities in which screening had started, precaution is mentioned as a reason for a recent clinical mammogram among women aged less than 70 more often than in municipalities without screening. Furthermore, mammography performed because of complaints is mentioned less in all age groups after the introduction of screening. After a clinical mammogram, further assessment procedures (cytology/needle biopsies 8%, biopsies 10%) were considered necessary about 10 times more often than after a screening mammogram.

Although the screening programme has almost no impact on the frequency of mammography in women who underwent a clinical mammogram, there has been a shift in reasons for these mammograms more towards reasons of prevention. Screening mammograms lead to a much smaller percentage of additional examinations than do clinical mammograms.