Reported drop in mammography

Is this cause for concern?

Authors

  • Nancy Breen PhD,

    Corresponding author
    1. Health Services and Economics Branch, Applied Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, Maryland
    • Health Services and Economics Branch, Applied Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Executive Plaza North, Room 4005, 6130 Executive Boulevard, MSC 7344, Bethesda, MD 20892-7344
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    • The findings and conclusions in this report are those of the authors and do not necessarily represent the views of their respective agencies.

    • Fax: (301) 435 3710

  • Kathleen A. Cronin PhD,

    1. Division of Cancer Control and Population Sciences, National Cancer Institute; Bethesda, Maryland
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    • The findings and conclusions in this report are those of the authors and do not necessarily represent the views of their respective agencies.

  • Helen I. Meissner PhD,

    1. Division of Cancer Control and Population Sciences, National Cancer Institute; Bethesda, Maryland
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    • The findings and conclusions in this report are those of the authors and do not necessarily represent the views of their respective agencies.

  • Stephen H. Taplin MD,

    1. Division of Cancer Control and Population Sciences, National Cancer Institute; Bethesda, Maryland
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    • The findings and conclusions in this report are those of the authors and do not necessarily represent the views of their respective agencies.

  • Florence K. Tangka PhD,

    1. Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Bethesda, Maryland
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    • The findings and conclusions in this report are those of the authors and do not necessarily represent the views of their respective agencies.

  • Jasmin A. Tiro PhD,

    1. Division of Cancer Control and Population Sciences, National Cancer Institute; Bethesda, Maryland
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    • The findings and conclusions in this report are those of the authors and do not necessarily represent the views of their respective agencies.

  • Timothy S. McNeel BA

    1. Information Management Services, Inc., Rockville, Maryland
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    • The findings and conclusions in this report are those of the authors and do not necessarily represent the views of their respective agencies.


  • This article is a US Government work and, as such, is in the public domain in the United States of America.

Abstract

BACKGROUND

Timely screening with mammography can prevent a substantial number of deaths from breast cancer. The objective of this brief was to ascertain whether recent use of mammography has dropped nationally.

METHODS

The authors assessed the trend in mammography rates from 1987 through 2005. Then, they used the 2000 and 2005 National Health Interview Survey (NHIS) estimates to characterize trends and current patterns in mammography use.

RESULTS

After robust, rapid increases in reported use of mammography by women in the U.S. since 1987, estimates from the 2005 NHIS showed a decline compared with 2000 (from 70% to 66%). Although it was small, this decline may be cause for concern, because it signals a change in direction.

CONCLUSIONS

This report establishes for the nation what already has been observed in some local data. The results confirmed that the use of mammography may be falling. This change needs to be monitored carefully and also may call for intervention. Cancer 2007. Published 2007 by the American Cancer Society

Between 1987 and 2000, the percentage of women in the U.S. aged ≥40 years who reported that they had a mammogram in the previous 2 years increased dramatically, from 39.1% to 70.1%,1 and already exceeded the Healthy People 2010 target of 70%.2 After rapid increases until 2000, rates stabilized between 2000 and 2003.3 The increase in the use of mammography over time has made early detection of breast cancer more common and has helped reduce mortality from this disease.4 Despite the great success of mammography in detecting breast cancer early, recent articles in the popular press suggest a decline in the rates of mammography use among women in Michigan,5 Iowa,6 and Florida.7 In addition, Feldstein et al.8 reported that screening mammography declined between 1999 and 2002 from 67% to 62.5% among patients in a nonprofit group-model health maintenance organization (HMO) in the Pacific Northwest. Even more disturbing, 33 states have reported a decline in mammography claims for Medicare beneficiaries. Finally, a recent report that used data from the Behavioral Risk Factor Surveillance System (BRFSS) indicated that there was a statistically significant decline in mammography rates in women aged ≥40 years from 76.4% in 2000 to 74.6% in 20059; however, not all states administered the mammography questions.

The objective of this brief was to ascertain whether the recent use of mammography has dropped nationally. We defined recent as self-reported receipt in the previous 2 years among women aged ≥40 years. This definition reflects prevailing recommendations.10 We computed mammograms for any purpose, because women who obtain a mammogram for diagnostic purposes would not be expected to obtain another for screening purposes. Only 1 mammogram was counted for any women, including those who reported >1 mammogram during the period defined as recent. First, we assess the trend in rates from 1987 through 2005; then, we compare estimates from 2000 and 2005 to characterize trends and current patterns in mammography use.

We used the National Health Interview Survey (NHIS) to examine trends and patterns in the recent use of mammography, because it is the primary source of health information on the civilian, noninstitutionalized population in the U.S., and it was designed specifically to produce national estimates.11 An annual survey that is administered in person by Census Bureau interviewers, the NHIS uses a complex, stratified, multistage sample to provide data representative of the U.S. population.12 Approximately 35,000 adults are interviewed, and response rates for the questions fielded in the cancer module are in the range of 80%.13, 14

Adult female respondents aged ≥40 years were asked a series of questions to determine the timing of their most recent mammogram. They were first asked, “Have you ever had a mammogram?” Women who responded affirmatively were then asked, “When did you have your last mammogram?” In 2005, the skip pattern was modified to specify the month for women who did not provide it initially. We took advantage of this additional information when computing rates in 2005 and differences between years. We examined adherence to recommendations for mammography, ie, receipt within the past 2 years, using the 1987, 1992, 1998, 2000, 2003, and 2005 NHIS.

First, we examined NHIS data from 1987 to 2005 to ascertain whether recent use of mammography was lower in 2005 than in previous years. Then, we examined the 2000 and 2005 data for trends and patterns for all women and for several subpopulations. Confidence intervals were calculated using SUDAAN software (release 9) to account for the complex survey design.15 We used SUDAAN Proc Descript to perform Student t tests to determine whether differences between estimated percentages in 2000 and 2005 were significant, because t tests are more accurate than comparisons of confidence intervals.16 Data in Table 1 are standardized to the 2000 U.S. standard population by 5-year age groups, except for the age group variable (groups aged 40–49 years, 50–64 years, and ≥65 years). Data in Figure 1 are not age standardized, because the figure shows separate age groups.

Figure 1.

Recent (within 2 years) mammography use among women by age. Black line indicates women aged ≥40 years; blue line, women aged ≥65 years; green line, women aged 50 years to 64 years; red line, women aged 40 years to 49 years.

Table 1. Comparison of Mammography Rates Among Women Aged ≥40 Years by Characteristics: The 2000 and 2005 National Health Interview Surveys
Characteristic2000 NHIS2005 NHISDifference
No.%95% CINo.%95% CI
  • NHIS indicates National Health Interview Survey; 95% CI, 95% confidence interval; AA, some college or associate degree; BA, Bachelor of Arts; BS, Bachelor of Science; HMO, health maintenance organization; AIAN, American Indian/Alaska Native; Ob/Gyn, obstetrician/gynecologist.

  • *

    The difference between the 2000 and 2005 estimates was statistically significant based on a t test.

  • Except for the age-group variable (ages 40–49 years, 50–64 years, and ≥65 years), estimates were standardized to the 2000 U.S. Standard Population by 5-year age groups.

Total  N = 10,212  N = 10,076 
 %10,21270.169–71.210,07666.465.2–67.5−3.8*
Age, y  N = 10,212  N = 10,076 
 40–49330864.262.2–66.2308763.561.4–65.5−0.7
 50–64334978.676.8–80.3372771.870.2–73.4−6.8*
 ≥6535556866.1–69.8326263.861.7–66−4.1*
Education  N = 10,142  N = 10,004 
 Less than high school235257.254.4–59.9193253.850.8–56.7−3.4
 High school graduate331868.566.6–70.3308563.661.5–65.6−4.9*
 Some college or AA degree253672.670.7–74.5269769.167.2–71−3.5*
 College graduate (BA/BS)19368077.9–82229076.374.5–78.1−3.7*
Family income as percentage of the poverty level, $  N = 10,212  N = 10,076 
 <200283355.853.4–58.2267652.149.7–54.5−3.7*
 200–299123066.463–69.6129965.462.3–68.3−1
 300–39990771.768.6–74.7105168.765.4–71.7−3.1
 400–49974877.173.3–80.669772.568.7–76−4.6
 ≥500185382.880.6–84.8192776.574–78.8−6.3*
 Unknown264169.767.6–71.8242664.662.1–67.1−5.1*
Have a usual source of care  N = 10,211  N = 10,075 
 No79334.630.8–38.776434.130–38.4−0.6
 Yes94187371.9–74.1931168.967.8–70.1−4.1*
Health insurance, age <65 y  N = 6633  N = 6800 
 Private, HMO197877.575.2–79.6154475.172.7–77.4−2.4
 Private, non-HMO291876.574.7–78.2328373.671.8–75.2−3*
 Public only73265.260.9–69.291957.953.6–62−7.3*
 Uninsured100541.437.7–45.210543834.6–41.6−3.3
Health insurance, age ≥65 y  N = 3544  N = 3260 
 Medicare HMO57471.166.5–75.437369.263.1–74.7−1.9
 Private20077168.8–73.1177567.464.9–69.8−3.5*
 Medicaid, military, other government37457.952.9–62.840756.751–62.2−1.2
 Medicare fee-for-service53956.151.4–60.767257.152.3–61.71
 Uninsured or Medicare Part A only5039.326.2–54.23344.629.3–61.15.3
Chronic disability  N = 10,123  N = 10,039 
 Yes250165.863.4–68.1248860.657.8–63.2−5.2*
 No762271.670.3–72.8755168.166.7–69.4−3.5*
Race/ethnicity  N = 10,195  N = 10,057 
 Hispanic125860.757.5–63.8126558.955.1–62.6−1.7
 Non-Hispanic white72537270.7–73.271136866.6–69.3−4*
 Non-Hispanic black145067.864.7–70.8138464.561.3–67.5−3.3
 Non-Hispanic AIAN5852.140.9–634967.257.1–75.815.1
 Non-Hispanic Asian17658.150–65.72465446.9–61−4
Race  N = 9921  N = 10,050 
 White819771.270–72.483256765.7–68.3−4.2*
 Black147267.664.5–70.6140764.160.9–67.2−3.5
 AIAN7252.341.7–62.86966.358.1–73.514
 Asian18058.750.5–66.524954.147–61−4.7
Immigration status  N = 10,102  N = 10,049 
 In U.S. <10 y18039.330.4–48.91534737.3–56.97.7
 In U.S. ≥10 y104064.761.2–68116963.560.2–66.6−1.2
 Born in U.S.888271.370.1–72.587276765.8–68.3−4.3*
Saw/talked to general physician in past 12 mo  N = 10,204  N = 10,067 
 Yes781375.574.3–76.7782071.570.2–72.8−4*
 No239152.650.1–55224747.845.4–50.3−4.8*
Saw/talked to Ob/Gyn in past 12 mo  N = 10,204  N = 10,070 
 Yes363987.586.2–88.7349585.684–87−1.9
 No656559.658.1–61657554.653–56.1−5*

Figure 1 shows that an upward trend in recent use of mammography was observed from 1987 to 2000 for all women (Fig. 1, black line) and for women ages 40 to 49 years (Fig. 1, red line), 50 to 64 years (Fig. 1, green line), and ≥65 years (Fig. 1, blue line). Rates from 2000 to 2003 were essentially the same. Data from 2005 suggest a decline, one that was especially marked for women aged 50 to 64 years. Vertical lines in Figure 1 indicate the confidence intervals for each point estimate.

Estimated mammography rates were nearly 4% lower in 2005 compared with the rates in 2000, and the difference was significant, as shown in Table 1. Rates were lower in 2005 than in 2000 for nearly all of the different groups of women examined. The largest significant declines were among women who traditionally have used mammography at high rates, including women ages 50 to 64 years and women with higher incomes. These 2005 estimates signify the first time that nationally representative data have shown a significant decline in the use of mammography in the U.S., and they are distributed throughout the groups for which screening is recommended. Significant declines were observed among non-Hispanic white women, women aged ≥50, women with higher educational attainment, women who reported a usual source of care, and women ages 40 to 64 years who had private non-HMO heath insurance coverage or public insurance coverage. We also computed mammography rates for 2005 data using the method employed for the 2000 data as much as possible; this method showed a smaller but still statistically significant drop (from 70.1% to 68.3%). Future monitoring will be critical to establish whether the use of mammography will continue to decline.

We should note that screening rates may be lower than reported by the NHIS, because studies have indicated that self-report may overestimate screening relative to what is determined by reviewing the medical records. Nevertheless, because there is no reason to believe that the direction or degree of overestimation has changed over time, the measurement of trends should not be affected. Our findings confirm for the entire U.S. a recent report using BRFSS data that showed a statistically significant decline in mammography rates among women aged ≥40 years.9 NHIS data are representative of the entire U.S., and the survey is administered in person, so that it includes individuals without a telephone; BRFSS is a telephone survey, and questions concerning mammography use were not administered to women in all states.

The looming questions are whether the decline in mammography will continue and how it will affect mortality rates from breast cancer. In addition to those questions is the challenge of explaining the decline: The drop in rates may be caused by numerous factors, including an increase in the number of women who do not have health insurance, higher copayments for office visits, less certainty regarding the desirability of screening because of perceived inconsistent findings on the effectiveness of mammograms in preventing deaths from breast cancer, reduced perceived risk because of reports of decreasing mortality from breast cancer, and a lack of emphasis on mammography in health promotion campaigns. In a recent Institute of Medicine report, it was speculated that a decline in mammography may have been caused by decreased mammography capacity because of low reimbursement by insurers, rising malpractice litigation against radiologists who read mammograms, and fewer radiologists choosing to specialize in breast imaging.17

Changes in screening rates have an immediate impact on the reported incidence of breast cancer and, ultimately, mortality. When a screening test is introduced, patients will be diagnosed earlier, leading to a rise in incidence relative to prescreening levels. This is because patients who would have had their disease detected clinically in the future will be brought forward into the year in which their disease was detected by screening.18 Conversely, when screening rates drop, women who are diagnosed with breast cancer who had stopped screening will be detected later than if they had continued screening, and this will result in a short-term drop in incidence. Just as an increase in incidence associated with screening is a positive indication of dissemination and will lead to an eventual reduction in mortality for the population, a decrease in incidence associated with a decline in screening may presage a future increase in mortality from breast cancer. The Annual Report to the Nation on the Status of Cancer published in the journal Cancer19 indicates a much-anticipated leveling off and possible decline in the incidence rate for breast cancer in 2003. This decline occurred over approximately the same period as the decline in the use of mammography. Consequently, we are concerned that some of the observed decline in incidence may be caused in part by the leveling off and reduction in mammography rates. If future NHIS data continue to show a decline in mammography use, then, as a nation, we need to be prepared to address it.

Since we observed the drop in mammography rates, our group has been working to develop a conceptual framework for evaluating the factors that influence mammography use and may have caused the drop in mammography rates that we observed. The extent to which the decline in incidence rates for breast cancer is associated with this drop also needs to be investigated. Although these findings are preliminary, together, they call for continued monitoring of trends in incidence, screening, and their underlying factors. It is not too early to consider what types of interventions would be needed should these downward trends continue.

Acknowledgements

We thank Penny Randall-Levy for help managing references.

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