Mammography

An X-ray image of the breast used to detect irregularities in breast tissue. In the National Health Interview Survey (NHIS), questions concerning use of mammography are included on an intermittent schedule. Mammograms may be used for diagnostic or screening purposes; however, the purpose cannot be determined from NHIS data.

In Health, United States, use of mammography is defined as the percentage of women aged 40 and over having a mammogram within the past 2 years. Survey questions have changed over time.

NHIS asks women aged 30 and over if they ever had a mammogram. Those who answer “yes” are asked when they had their most recent mammogram. In 1987 and 1990, women were asked to report the number of days, weeks, months, or years that had passed since their most recent mammogram. In 1991, women were asked whether they had a mammogram in the past 2 years. In 1993 and 1994, women were asked whether they had a mammogram within the past year, between 1 to 2 years ago, or more than 2 years ago. In 1998, women were asked whether they had a mammogram a year ago or less, more than 1 year but not more than 2 years ago, more than 2 years but not more than 3 years ago, more than 3 years but not more than 5 years ago, or more than 5 years ago.

In 1999, women were asked to report the number of days, weeks, months, or years that had passed since their most recent mammogram. Estimates for 1999 may be slightly overestimated in comparison with previous years: Women who responded “2 years ago” (10% of women) may include those who received a mammogram more than 2 years but less than 3 years ago.

In 2000 and 2003, women were asked when they had their most recent mammogram (month and year). Women who did not respond were given a follow-up question that used the 1999 wording, and women who did not respond to the 1999 wording were asked a second follow-up question that used the 1998 wording. Estimates for 2000 and 2003 may be slightly overestimated in comparison with estimates before 1999: Women who responded “2 years ago” (2% of women) may include those who received a mammogram more than 2 years but less than 3 years ago.

In 2005, women were asked the same series of mammography questions as in the 2000 and 2003 surveys, but the questionnaire skip pattern was modified so that more women were asked the follow-up question using the 1998 wording. As a result, estimates for 2005 and subsequent years are more precise than estimates for 1999, 2000, and 2003. SAS code to categorize mammography data for 2000 and beyond is available from: https://www.cdc.gov/nchs/nhis/nhis_2005_data_release.htm. The same mammography questions were asked from 2005 to 2018. In 2019, women were asked questions about mammography with slightly different question and response wording. Due to this and other methodological changes to the survey, estimates for 2019 and beyond are not considered comparable with estimates for earlier years.

Data from mammography questions can be found in the following NHIS files: Sample Adult (1999, 2000, 2003, 2008, 2013, 2018, 2019), Sample Adult cancer (2005, 2010, 2015), Sample Adult prevention (1998), year 2000 objectives (1993, 1994), cancer control (1987), health promotion and disease prevention (1990, 1991), and cancer control supplement (1987). From 2019 to 2025, questions on use of mammography will be included every other year in the Sample Adult file.

The recommended age to begin mammography screening and the interval between screenings has changed over time. The current recommendation, made by the U.S. Preventive Services Task Force (USPSTF) in 2016, is the use of mammography for breast cancer screening every 2 years for women aged 50–74. For women aged 40–49, USPSTF notes that the decision to start screening should be an individual one, taking into account a woman’s health history, preferences, and how she weighs the different potential benefits and harms. USPSTF concludes that the current evidence is insufficient to evaluate the balance of benefits and harms of screening mammography in women aged 75 and over. For additional information, see the USPSTF website on Breast cancer: Screening at: https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/breast-cancer-screening.