- Top of page
- MATERIALS AND METHODS
- FUNDING SUPPORT
- CONFLICT OF INTEREST DISCLOSURES
Screening mammography reduces breast cancer mortality by approximately 15% in women aged ≥ 40 years.[1-3] Although rates of screening mammography have increased substantially in the past 3 decades, approximately 25% of US women aged ≥ 40 years report having no recent screening mammogram, and this percentage varies widely from state to state.[4, 5] In addition to its use as a screening and diagnostic tool, mammography is also a fundamental part of posttreatment surveillance among survivors of breast cancer. Approximately 20% of women with a history of breast cancer do not adhere to guidelines for follow-up mammography.[6-10]
The availability and accessibility of mammography depend on several factors, including the supply and location of mammography equipment and personnel. Although prior reports suggested that overall mammography capacity in the United States was large enough to meet existing needs,[11, 12] it is not clear whether resources are currently distributed proportionally to the population across local areas or are sufficient to meet national targets for breast cancer screening.
In light of reported declines in the rates of screening mammography and financial pressures facing many mammography facilities,[14-16] it is especially critical to understand how the availability and accessibility of mammography resources affect mammography use and outcomes. The goals of the current study were to evaluate trends in the number and distribution of mammography resources in the United States and to assess the impact of socioeconomic and health care market characteristics on changes in the availability of mammography services.
- Top of page
- MATERIALS AND METHODS
- FUNDING SUPPORT
- CONFLICT OF INTEREST DISCLOSURES
Mammography remains the only recommended modality of population-based screening for breast cancer.[19-21] In this analysis, we observed declines in the availability of mammography facilities and machines between 2000 and 2010, as well as a decrease in county-level mammography capacity. The counties affected by significant declines in mammography capacity represented almost three-quarters of the female population aged ≥ 40 years.
Several population characteristics were associated with cross-sectional variation in mammography capacity as well as changes in capacity over time. Although the percentage of rural residents in 2000 was positively associated with an increase in capacity between 2000 and 2010, counties with more rural residents had lower capacity compared with other counties in each year. The results of the current study suggest that counties whose populations had lower educational attainment, increasing poverty rates, and a growing percentage of elderly residents were particularly vulnerable to declines in mammography capacity.
Approximately one-quarter of all US counties had no mammography facilities in any year. This percentage was stable over time and similar to prior estimates. However, when weighted for the population distribution, these areas represented only 3% of US women aged ≥ 40 years. Lack of resource capacity is likely a barrier to breast cancer screening in these areas, and initiatives that establish or expand mobile mammography programs in neighboring counties may improve access for women who reside in zero-capacity counties.
Several health care market factors were found to be correlated with mammography capacity. Counties with more uninsured residents or higher managed care penetration had lower capacity and were more likely to experience a decline in capacity. Both low health insurance coverage rates and high managed care penetration could potentially limit the profitability of health care services, especially preventive services, which may not be generously reimbursed by insurers and may be viewed as unnecessary by uninsured women who would have to pay for them out of pocket. Although some studies have found better adherence with breast cancer screening recommendations among managed care enrollees compared with their peers who are covered by traditional fee-for-service insurance policies,[23-25] lower mammography capacity may be a barrier to breast cancer screening for women living in areas with high managed care penetration.
Mammography capacity was not significantly influenced by the number of radiologists per population. This is not surprising given the relatively low reimbursement of mammography and other real or perceived negative attributes of mammography, such as job stress and fear of malpractice, compared with other types of imaging services. Although the mean number of radiologists per 100,000 county residents increased between 2000 and 2010, this change did not improve the availability of screening mammography for women in most counties, perhaps because new radiologists chose more lucrative and technologically interesting practice areas. Thus, policies aimed at the radiology workforce may not be the most effective levers for improving access to screening mammography.
Access to mammography has been a particular concern in the United States since the passage of the MQSA, enacted in 1992, which established national uniform quality standards for mammography.[17, 27, 28] The MQSA has been credited with substantial improvements in mammography quality, and in earlier reports federal analysts concluded that the law has not impaired access to mammography services.[29-31] From 1994 to 1997, facility closures were nearly offset by new facility openings or reopenings, and nearly all facilities that closed were located within 25 miles of another certified mammography facility.[30, 31] Between 1998 and 2001, the number of certified facilities declined by approximately 5%, but the total number of mammography machines increased by 11%. The declines we observed in mammography facilities, machines, and capacity per population between 2000 and 2010 were not likely related to federal legislation, but they renew earlier concerns about access to breast cancer screening services.
The results of the current study also reinforce earlier anecdotal and empirical evidence that some areas may be disproportionately impacted by mammography facility closures. A prior survey of selected counties found that in some metropolitan areas, demand for mammography has grown while capacity has declined, leading to long waiting times and temporary interruptions in mammography availability. Our surveys of mammography facilities in 6 states in 2008 and 2011 suggested that wait times for the next available screening mammogram appointment are longer at facilities in counties with lower mammography capacity.[32, 33]
In the current study, we assumed that the imaging capacity of every machine is identical, while in fact, newer mammography machines may be more efficient than older machines, producing more scans per unit over the unit's lifetime. Our study period coincided with the widespread dissemination of digital mammography, which was approved for clinical use in January 2000. In 2008, 54% of mammography facilities in 6 states reported that they offered digital mammography or were in the process of acquiring digital mammography equipment. By 2011, 78% of facilities in the same 6 states reported that they offered digital mammography. Compared with screen-film mammography, digital mammography is associated with a significantly shorter image acquisition time. In the current study we were not able to account for variability across facilities with regard to their average throughput or hours of operation.
Similarly, we addressed neither the availability of radiologic technologists nor the quality of services provided. The credentials and minimum number of personnel at each facility are regulated by the MQSA to some extent, and machine condition and image quality are monitored in mandatory annual facility inspections. However, some facilities may exceed the minimum standards, contributing to heterogeneity in service quality and capacity between facilities.
Ultimately, we are concerned with the impact of mammography capacity on the likelihood of screening. National surveys have routinely documented geographic variation in rates of screening mammography use, and our prior research suggests that women in counties with inadequate mammography capacity are less likely to have screening mammograms. It is not clear whether interventions for improving geographic access to screening should involve direct operation or relocation of resources by public health authorities, incentives for radiologists to offer screening mammography in low-capacity areas, or other strategies. However, by identifying county-level demographic and health care market characteristics associated with lower mammography capacity and declines in capacity, interventions can target those areas in greatest need of enhanced resource availability and those at greatest risk of further declines in mammography capacity.