Abstract
Introduction
The U.S. Preventive Services Task Force (USPSTF) modified their screening guidelines for breast cancer in November 2009. Previous studies evaluated the impact of these guideline changes among privately and Medicare insured populations. Women in the military form a unique population exposed to many social, environmental, and occupational hazards that may increase breast cancer incidence. By evaluating mammography screening rates among women in the military before and after the USPSTF guideline changes, this study evaluated the impact of the USPSTF breast cancer guideline change on screening mammography use within the military population and determined whether current guidelines were followed for this high-risk population with universal health care access.
Materials and methods
This study evaluated the impact of the 2009 guideline changes among the population of universally insured military servicewomen, comparing the proportion of active duty women aged 40 to 64 receiving mammograms from fiscal years 2006 to 2015 using an interrupted time series analysis. Stratified analyses evaluated differences by age (aged 40–49, 50–64), race, military branch, and rank. This research is considered exempt by the Uniformed Services University Institutional Review Board.
Results
The proportion of insured military servicewomen receiving mammograms increased from October 2005 through September 2009. A significant decrease occurred in the first quarter of 2010 following the publication of the screening guideline update. From this new baseline, the proportion of women screened increased again through September 2015. Comparative analyses showed more pronounced effects both immediately and over time among the women aged 50 to 64 compared to those aged 40 to 49 years and among older enlisted women compared with their officer counterparts. The patterns were near identical in all subgroups; however, no changes in rate were evident among Air Force and black servicewomen aged 50 to 64 and Army and Navy/Marine Corps servicewomen aged 40 to 49 years. No racial disparities in screening or impact were noted.
Conclusions
The USPSTF guidelines had differential impacts among some subpopulations. While older women, aged 50 to 64 years, had a greater temporary reduction immediately after the guideline change, younger women aged 40 to 49 years had a longer-term reduction in screening following the guideline changes. No racial disparities in the proportion screened or in the impact of the guideline change were noted in this population with universal health coverage. The lack of Department of Defense standard breast cancer screening guidelines was evident from the different patterns of mammography utilization observed among military branches. To completely understand the impact of the updated screening guidelines, future studies must incorporate research focusing on changes in breast cancer morbidity and mortality as well as updated cost-benefit analyses.
INTRODUCTION
Breast cancer is one of the leading causes of cancer death among women in both the United States and the world. Since the American Cancer Society first recommended mammography as a routine tool for breast cancer screening in the 1970s, a 5-year survival from breast cancer has increased from 75% to currently over 90%.1,2 Taking the major advancements in treatments into account, routine screening mammography can still be credited with a portion of this reduction in mortality.3,4
Currently, over 200,000 women serve in the U.S. Military on active duty status, comprising 15.5% of military forces. Including reserve and National Guard units increases this number to over 355,000 women and 16.8% of the total military force.5 These women form a unique population exposed to many social, environmental, and occupational hazards that may increase breast cancer incidence. Several studies reported an increased risk of breast cancer among active duty military women.6,7 Currently, mammography is the primary population-level breast cancer screening tool available. Since mammography was found to be an acceptable and effective method to screen for breast cancer at the population level, who should be screened, age at which screening should start, and how often screening should occur have been widely debated.3,8–12
Previous guidelines recommended annual or biennial screening for all women beginning at age 40. In November 2009, the U.S. Preventive Services Task Force (USPSTF) changed its breast cancer screening guidelines. The new USPSTF guidelines called for shared decision-making regarding the onset and frequency of mammograms between health care providers and women under age 50. The new guidelines recommended regular biennial screening for women beginning at age 50.13,14 In contrast to the USPSTF, other medical organizations such as the American Cancer Society, the American College of Obstetricians and Gynecologists, the American College of Radiology, and the Society for Breast Imaging recommend annual screening beginning at age 4015,16 or annual screening from ages 45 to 54 and biennial screening thereafter.17
While the Army, Air Force, and Navy medical providers all operate within the Military Health System (MHS), the different military services themselves do not have shared screening guidelines.18–21 There are additional guidelines applicable to deploying military units that can supersede those of the individual service branches. This military study population with universal health coverage may not have the same socioeconomic factors impacting access to screening mammography as the general U.S. population. By evaluating mammography screening rates among women in the military before and after the USPSTF guideline changes, this study evaluated the impact of the USPSTF breast cancer guideline change on screening mammography use within the military population and determined whether current guidelines were followed for this high-risk population with universal health care access.
METHODS
Data Source and Study Population
This retrospective cohort study queried the Military Health System Data Repository (MDR) claims data for all diagnostic and screening mammograms from fiscal years (FY) October 1, 2006, through September 30, 2015, for all active duty women aged 40 to 64 years old. The Defense Enrollment Eligibility Reporting System (DEERS) data provided demographic characteristics (race, rank, branch of service) for the eligible population. Personnel information in DEERS is updated monthly and collected from the Defense Manpower Data Center and acts as the central repository for demographic information for service members and their dependents.
The MDR contains health care encounter and claims data for care provided at military treatment facilities (MTFs/direct care) and at civilian fee-for-service treatment facilities (purchased care) through TRICARE. TRICARE is the MHS insurance product that provides universal health care coverage to 9.4 million beneficiaries, which include active duty military personnel, retirees, and their dependents. TRICARE is separate from the Veterans Affairs (VA) system and does not include care provided at VA hospitals or in combat zones.22
Outcomes and Measures
We defined screening rate as the proportion screened for each quarter of each FY, based on nationally recognized standards.23 We calculated the proportion screened for each quarter of each FY from the number of screening mammograms performed divided by the total number of servicewomen. Screening mammograms were defined based on International Classification of Diseases, Ninth Revision, Current Procedural Terminology (CPT), and Healthcare Common Procedure Coding System (HCPCS) codes (V76.10, V79.11, V76.12, 87.36, 87.37, 76083, 76085, 76092, 77052, 77057, 77063, G0202, G0203). Diagnostic mammogram codes were defined by CPT/HCPCS and excluded from the primary analysis (76082, 76090, 76091, 77051, 77055, 77056, G0204, G0205, G0206, G0207, G0279).
We also evaluated the impact of the 2009 USPSTF guideline change on mammography screening rates stratified by age (40–49 and 50–64), race (white, black, other), branch of service (Army, Air Force, and Navy/Marine Corps), and rank category (enlisted, officer). We chose age groups to correspond with the age groups addressed in the USPSTF guideline but limited this study to women under age 65 as the focus was on an active duty military population. We only presented results by race for black and white women due to a small number of women in other racial categories. Due to the small number of female Marines, their data was combined with the Navy personnel since the Marine Corps typically received health care from Navy providers. Limited sample sizes precluded stratification by race within rank category or service branch or by rank category within service branches.
Data Analysis
We evaluated the impact of policy change with an interrupted time series (ITS) accounting for baseline trends in each group described (race, service branch, and rank category all stratified by age) using the following model: Y = β0 + (β1) (time t) + (β2) (intervention t) + (β3) (time after intervention) + εt. We additionally evaluated the difference between groups using a multiple-group analysis: Y = β0 + (β1) (time t in reference group) + (β2) (intervention t in reference group) + (β3) (time after intervention in reference group) + (β4) (time t in other group) + (β5) (intervention t in other group) + (β6) (time after intervention in other group) + (β7) (time after intervention in other group) + εt. We looked at both immediate effects as measured by the change in rate immediately (change in intercept) following the guideline change and the effects over time as measured by the change in rate from the guideline change to the end of the study period (change in slope). Potential seasonal trends in screening mammography utilization were addressed by fitting the model using Newey-West standard errors to address autocorrelation.24,25
We performed several additional analyses to assess the robustness of our results. An implementation period of one quarter was tested to evaluate for a delay of full effect of the USPSTF guideline change.26 We conducted additional analyses with all mammograms, both screening and diagnostic, to determine the effects of potential misclassification of mammogram type on the results.
Given the USPSTF based their screening guidelines on age, we considered the age structure of the population across the study period. Both the mean and median age of women in the 40 to 49 year and the 50 to 64 year age group remained approximately constant, varying by no more than 1 year, throughout the study period. Even so, ITS is not considered sensitive to changes in population structure over time; thus no age adjustment was performed.26
Data for immediate effects and effects over time are presented as the number of women who received screening mammograms per 10,000 per quarter with corresponding 95% confidence intervals found within the specified data tables. All P values are two-sided with a significance level of 0.05. We used SAS, version 9.4, for data extraction (SAS Institute Inc., Cary, North Carolina) and Stata, version 15 (StataCorp, College Station, Texas), for all analyses. Stata, version 15, was used for the ITS analysis (StataCorp, College Station, Texas). This research was considered exempt by the Uniformed Services University of the Health Sciences Institutional Review Board.
RESULTS
Study Population
The women in this study contributed a total of 361,964 person-years over the 10-year study period with 84.4% of the time in the 40- to 49-year age group and 56.0% with an enlisted rank (Table I). Approximately 47.5% were in the Army, 28.5% in the Air Force, and 16.8% in either the Navy or the Marines. Approximately 56.6% of the women were white, 31.7% were black, and 11.7% were of another race. The percentage of women in the older age group slightly increased across the study period, but the median age of women in each age group remained the same. The proportion of women in each service branch remained consistent over the entirety of the study period (Army, 45–47%; Air Force, 31–28%; and Navy/Marine Corps, 19–17%). The percentage of black women stayed approximately constant throughout the study period, whereas the proportion of white women decreased by 6.3%, and those of other races increased by 5.8% between FY 2006 and 2015. The percentage of enlisted women declined by 6.6% over the study period.
TABLE I.
Population Characteristicsa
| FY 2006 n = 36,408 | FY 2010 n = 38,061 | FY 2015 n = 33,340 | |
|---|---|---|---|
| Age | |||
| 40–49, % | 85.4 | 84.5 | 83.6 |
| 50–64, % | 14.6 | 15.5 | 16.4 |
| Race | |||
| White, % | 59.9 | 56.5 | 53.6 |
| Black, % | 31.1 | 32.1 | 31.7 |
| Other, % | 8.9 | 11.5 | 14.7 |
| Branch | |||
| Army, % | 44.5 | 48.8 | 46.6 |
| Air Force, % | 30.5 | 28.1 | 27.9 |
| Navy/Marines % | 18.5 | 16.1 | 16.9 |
| Rank | |||
| Enlisted, % | 59.0 | 57.3 | 52.4 |
| Officer, % | 37.1 | 38.2 | 42.0 |
aSubgroup totals may not total 100% as Coast Guard, warrant officers, and unknown branch or rank were not included for sub-analyses.
Overall Results
For both age groups (40–49 and 50–64), the rate of women having mammograms in this military population increased from FY 2006 through the end of FY 2009 (40–49 years, 20 more screened quarterly per 10,000; 50–64 years, 28 more screened quarterly per 10,000) (Fig. 1, Table II). A statistically significant decrease in the mammography screening rate among servicewomen occurred in the same fiscal quarter as the release of the USPSTF guideline change, representing an immediate change in screening rates (40–49 years, decrease of 78 screened per 10,000; 50–64 years, decrease of 238 screened per 10,000) (Fig. 1, Table II). A comparative analysis showed a more pronounced statistically significant magnitude of immediate change in the 50- to 64-year age group (Table III). The change observed over time among servicewomen ages 40 to 49 was also statistically significant: screening rates increased at a lower rate following the change, as indicated by a negative change in slope (16 fewer screened quarterly per 10,000) (Table II). However, in the 50- to 64-year group, rates increased more rapidly after the recommendation then before the recommendation (48 more screened per 10,000) (Table II). Screenings also increased at a statistically significant higher rate in the 50- to 64-year-old group than in the 40- to 49-year-old group (64 more screened quarterly per 10,0000) (Table III).
FIGURE 1.
Quarterly screening rates from FY 2006 through 2015 comparing women aged 50 to 64 to those aged 40 to 49 overall and comparing black women to white women by age group.
TABLE II.
Single Group Analysisa
| Age Group | Baseline Rate | Slope Prior to Guideline Change | Slope After Guideline Change | Change in Rate (Immediate Effect) | Change in Slope (Effect Over Time) | |
|---|---|---|---|---|---|---|
| Overall | ||||||
| 40–49 | 460 (427, 493) | 20 (17, 24) | 5 (2, 7) | −78 (−124, −31) | −16 (−20, −11) | |
| 50–64 | 538 (463, 613) | 28 (20, 36) | 76 (65, 87) | −239 (−415, −63) | 48 (34, 63) | |
| Race | ||||||
| White | 40–49 | 462 (426, 497) | 19 (15, 22) | 3 (0, 5) | −73 (−114, −32) | −16 (−20, −12) |
| 50–64 | 533 (454, 612) | 27 (19, 34) | 70 (61, 79) | −188 (−329, −47) | 43 (31, 55) | |
| Black | 40–49 | 444 (394, 494) | 22 (16, 27) | 8 (6, 11) | −89 (−156, −22) | −13 (−19, −7) |
| 50–64 | 551 (427, 675) | 28 (14, 43) | 89 (72, 107) | −280 (−566, 5) | 61 (38, 84) | |
| Rank | ||||||
| Enlisted | 40–49 | 455 (412, 499) | 25 (21, 29) | 8 (5, 10) | −80 (−129, −30) | −17 (−22, −12) |
| 50–64 | 523 (423, 622) | 37 (28, 46) | 110 (92, 128) | −358 (−602, −114) | 73 (53, 93) | |
| Officer | 40–49 | 461 (429, 494) | 14 (11, 18) | 3 (0, 6) | −77 (−124, −29) | −11 (−16, −7) |
| 50–64 | 561 (488, 635) | 25 (16, 35) | 68 (56, 79) | −209 (−391, −26) | 42 (27, 58) | |
| Branch | ||||||
| Army | 40–49 | 415 (356, 474) | 20 (14, 26) | 4 (0, 9) | −80 (−170, 9) | −16 (−23, −8) |
| 50–64 | 511 (419, 602) | 30 (18, 41) | 57 (45, 69) | −285 (−500, −70) | 27 (10, 44) | |
| Air Force | 40–49 | 495 (464, 527) | 23 (21, 26) | 3 (1, 6) | −111 (−167, −55) | −20 (−24, −16) |
| 50–64 | 610 (477, 743) | 29 (17, 41) | 103 (87, 119) | −159 (−350, 32) | 74 (54, 94) | |
| Navy | 40–49 | 508 (457, 559) | 23 (18, 27) | 6 (1, 12) | 19 (−47, 85) | −17 (−23, −10) |
| 50–64 | 592 (478, 706) | 34 (26, 43) | 144 (130, 157) | −275 (−453, −96) | 109 (93, 126) |
aAll rates are women screened per 10,000 (95% confidence intervals) per quarter.
TABLE III.
Comparative Analysisa
| Age Group | Difference in Baseline Rates | Difference in Slopes Prior to Guideline Change | Difference in Slopes After Guideline Change | Change in Rate (Immediate Effect) | Change in Slope (Effect Over Time) | |
|---|---|---|---|---|---|---|
| Overall | ||||||
| (40–49)–(50–64) | −79 (−157, −1) | −7 (−16, 1) | −71 (−81, −62) | 161 (5, 318) | −64 (−77, −51) | |
| Race | ||||||
| White-black | 40–49 | 18 (−51, 87) | −3 (−10, 4) | −6 (−10, −2) | 16 (−71, 102) | −3 (−11, 5) |
| 50–64 | −18 (−151, 114) | −2 (−17, 13) | −20 (−35, −4) | 93 (−172, 357) | −18 (−39, 4) | |
| Rank | ||||||
| Enlisted-officer | 40–49 | −6 (−78, 66) | 11 (4, 18) | 5 (1, 9) | −3 (−86, 80) | −6 (−14, 2) |
| 50–64 | −39 (−144, 67) | 12 (0, 24) | 42 (26, 59) | −149 (−401, 103) | 30 (10, 51) | |
| Branch | ||||||
| Army-Air Force | 40–49 | −80 (−144, −17) | −3 (−9, 3) | 1 (−4, 5) | 30 (−64, 125) | 4 (−3, 12) |
| 50–64 | −99 (−251, 53) | 1 (−15, 17) | −46 (−64, −27) | −126 (−387, 135) | −47 (−71, −23) | |
| Army-Navy/Marines | 40–49 | −93 (−176, −10) | −3 (−11, 6) | −2 (−8, 4) | −99 (−209, 11) | 1 (−10, 11) |
| 50–64 | −81 (−229, 67) | −4 (−20, 11) | −87 (−101, −72) | −10 (−259, 239) | −82 (−103, −61) | |
| Air Force-Navy/Marines | 40–49 | −13 (−82,56) | 1 (−6, 8) | −3 (−9, 3) | −129 (−225, −33) | −3 (−13, 6) |
| 50–64 | 18 (−22, 10) | −6 (−22, 10) | −41 (−60, −22) | 116 (−138, 370) | −35 (−60, −10) |
aAll rates are women screened per 10,000 (95% confidence intervals) per quarter.
Results by Race
Screening mammography rates for both black and white servicewomen followed the same pattern exhibited by the overall active duty population (Fig. 1). There was an immediate statistically significant drop in the rate of screening mammograms at the time of the guideline change for all races and ages followed by a slower increase in the rate over time for younger women (white women, 16 fewer screened quarterly per 10,000; black women, 13 fewer screened quarterly per 10,000) and a faster increase in the rate over time for older women (white women, 43 more screened quarterly per 10,000; black women, 61 more screened quarterly per 10,000) (Table II). The comparative study showed no statistically significant difference in either the immediate or over time rates between black and white women (Table III). The only statistically significant difference was that black women in both age groups had a higher increase in screening over time following the guideline change (40–49 years, 6 more screened quarterly per 10,000; 50–64 years, 20 more screened quarterly per 10,000).
Results by Rank
Screening rates among enlisted and among officers followed the same pattern exhibited by the overall active duty population (Table II). All groups experienced a statistically significant immediate drop in screenings after the guideline change (enlisted 40–49 years, 80 fewer screened quarterly per 10,000; officer 40–49 years, 77 fewer screened; enlisted 50–64 years, 358 fewer screened per 10,000; officer 50–64 years, 209 fewer screened per 10,000). Enlisted women aged 50 to 64 exhibited a statistically significant larger increase in the mammography screening rate over time as compared to officers (30 more screened quarterly per 10,000) (Table III).
Results by Military Branch
Results varied for the different branches of military service. All branches observed a statistically significant change in rate of screening over time after the guideline change, consistent with those observed in the overall population as well as by race and rank category (Table II). However, only women ages 40 to 49 serving in the Air Force and women 50 to 64 in the Army, Navy, and Marine Corps saw a drop in the rate of mammography during the quarter of the guideline change (Table II). Comparing the branches to one another following the guideline change, we found that women aged 40 to 49 years serving in the Air Force saw a greater immediate decreased rate as compared to those in the Navy and Marine Corps (129 fewer screened per 10,000) (Table III). Over the time period following the guideline change among women aged 50 to 64, all branches were impacted differently. Women in the Navy and Marine Corps had the largest increases in the rate of screenings over time, and women in the Army had the smallest increase (Table III).
Additional Analyses
When we repeated the analysis under the assumption that the USPSTF recommendation change would take an additional 3 months (one quarter) to observe any influences, the results were consistent with the original analyses. We also performed additional analyses which included diagnostic mammograms as well as screening mammograms. Overall, the trends were similar to the initial analysis. While the direction and magnitude of the changes in rate and slope of the patterns held, some of the results were no longer statistically significant.
DISCUSSION
Overall, there was an increased rate of active duty military women receiving screening mammograms from FY 2006 through the end of FY 2009. There was a statistically significant decrease of this rate in the first quarter FY 2010 that coincided with the change in the USPSTF guideline for mammography screening frequency among women aged 40 to 64. Among women ages 40 to 49, the rate of increase was reduced between FY 2010 and 2015 compared to before the guideline change. Among women ages 50 to 64, however, the rate of mammography screening increased after the guideline change. The patterns were near identical in all subgroups; however, no changes in rate were evident among Air Force and black servicewomen ages 50 to 64 and Army and Navy/Marine Corps servicewomen ages 40 to 49.
Differences existed between women in the two age groups as would be expected given the variation in recommendations in the USPSTF guidelines for each group. In the subgroup analyses, there were only statistically significant differences in immediate changes between the Navy/Marine Corps and Air Force with women ages 40 to 49 in the Air Force showing a significant decrease of screenings. In terms of change over time, the statistically significant differences existed in every subgroup (age, race, rank category, service branch) of women ages 50 to 64 except for blacks as compared to whites.
While the USPSTF guideline change was temporally associated with statistically significant effects both immediately and over time in most groups analyzed, the changes were small in magnitude, especially for women in their 40s. This reduction in mammography rates may have been due to increased attention to breast cancer screening in the U.S. media, with most of this coverage being negative, following the release of the controversial guideline change.27 Medical providers, depending on their specialty, may also have followed conflicting recommendations from other medical organizations. These different recommendations may have caused more confusion for women. Women who had been receiving regular screening mammograms for many years may also have been more reluctant to reduce the frequency of these screenings. Research has suggested that both women and their providers are more inclined to adhere to the age 40 screening recommendation.12
Perhaps the most relevant finding of this study is the lack of racial disparities in mammography utilization the U.S. Military observed. There were no statistically significant differences between black and white women in the baseline rate of mammograms received in either age group, and the USPSTF guideline change had a similar impact on all groups. While some studies have documented lower rates of mammography screening among black women as compared to white,28–30 this disparity was not observed in the military as illustrated in this study as well as elsewhere.31 This study demonstrates that the guideline change impacted both black and white active duty servicewomen providing further evidence that a system designed with universal access to health care results in the application of policy changes that are considered uniformly without regard to race.
The differences noted between the military service branches is unsurprising as there is no Department of Defense (DoD), joint services consensus providing direction on preventive breast cancer screening. Once the USPSTF guidelines were updated in 2009, the Army publication was not updated to reflect the change resulting in conflicting statements where the Army mandates following the USPSTF recommendations while simultaneously stating that mammograms must be performed annually or biennially beginning at age 40.32 The Navy has mandated annual mammograms at age 40 during the entirety of the study period.33 The Marine Corps receives their medical care from Navy medical providers. The Air Force, in contrast, has left the age to initiate mammographic screenings up to the provider and patient to jointly decide.34 Overall, the older aged women in the Navy and Marine Corps were the most impacted by the guideline change over time and, along with the Army, experienced the most dramatic immediate drop in rate. It is possible that since most of the patterns of change and coefficients among the branches remained similar, these isolated differences may have been a result of a reduced sample size in the older age category. Among younger women, those in the Air Force, in which the regulation allows for shared decision-making, were more immediately impacted with a larger drop in screening rates compared to the women in the Army or Navy and Marine Corps. As the DoD continues to centralize the administration of the MHS under the Defense Health Agency, the findings presented in this study may provide evidence for developing consensus on a set of DoD standard cancer screening guidelines. Although such a consensus may still not exhort authority over preventive cancer screenings required for service members preparing for or serving on deployments, this would be a positive step in provision of clinical preventive services.
The observed changes in the mammography screening rate are not surprising based on the results of studies conducted outside the military health care system. Recommended changes for cervical and prostate cancer screenings and prior recommendations for mammography were also followed by immediate drops in the rates in which these services were provided.35–38 Earlier studies on civilian populations performed following the 2009 recommendation statement failed to find any statistically significant differences in rates of mammography for women in any age group before and after the publication of the USPSTF statement; however, these studies relied on self-reported survey data.39,40 Self-reported claims of mammography are recognized to be overreported.41 A series of studies, some using Medicare and some using privately insured civilian populations, were able to incorporate more robust techniques with statistical power and found that screening mammography rates decreased following the guideline change in women of all age groups.30,42–47 Of these studies, two found racial disparities in the new guideline’s impact.46,47 In contrast, our study, after stratifying by race within a health care system with universal access, found that the response to the 2009 USPSTF recommendation was equally experienced by women of both races.
When conducting analyses evaluating the effects of an intervention or policy over time, there may be concerns that other explanations can account for any observed changes. During the time the of the 2009 USPSTF guidelines change, a 2008 policy providing additional medical readiness guidance was in effect which required screening mammograms for all women aged 40 years or older within 1 year of a military deployment to the U.S. Central Command Area of Operations, no matter their individual branch of service.48 This policy changed in 2010 and deferred to service branch-specific guidelines.49 As it pertains to this study, there were no other medical organizations that changed or issued recommendations during the same timeframe as the USPSTF guideline statement that can explain the initial decrease in screening. Other recommendations were made later during the surveillance period in response to the USPSTF policy change. Also, these guidelines did not increase the recommended age for screening to begin nor reduce the recommended frequency of such screening. In 2010, the American College of Radiology, along with the Society for Breast Imaging, republished their previous guidelines recommending annual screening for women starting at age 40.16 The American College of Obstetricians and Gynecologists published updated guidelines in July 2011 recommending annual screening for women of average risk age 40 or above; they had previously recommended either annual or biennial screenings at age 40.15,50 While these more inclusive screening guidelines would not account for the immediate decline in screening as observed in this study, they may have contributed to the return of higher screening rates by the end of the study, diminishing the impact of the USPSTF statement.
This study is unable to determine whether the changed mammogram screening rate in this military population is a result of patient or provider preference. Some research recently determined that while health care providers understand the importance and influence of breast and cervical cancer screening recommendations published by the USPSTF, they are more likely to recommend these screening tests for their patients at levels above that recommended by the Task Force.51 This practice may point to the influence of provider preference although this study was limited to providers in the northeastern region of the United States.51
Major strengths of this analysis included the use of the ITS model, the size of the study population, and the diversity of this nationally representative population. Given that the ITS accommodates trends both before and after an intervention of interest, it is considered the most robust quasi-experimental approach.52 This model minimizes the influence of time-varying confounders such as changing age distributions which in this study minimally changed over the surveillance period and seasonality by adjusting for autocorrelation.24,26 This method can also incorporate a lag time to allow for a delay in the dissemination and integration of the intervention.24,26,53,54
This study evaluated the effects of the Task Force recommendation change on a population of individuals in a universal health care setting, thereby minimizing the impact of differential access as a potential confounder. The large population size allowed this study to evaluate differences by age, race, branch of military service, and military rank category separately.
There are several limitations to be addressed. Although this study was designed to understand the impact of the guidelines on the patterns observed in mammography utilization, it is possible that other unidentified factors also influenced the described trends. The analysis techniques assumed that the trends before FY 2010 would have continued uninterrupted had the USPSTF not issued new breast cancer screening guidelines in 2009. However, the results consistently showed a statistically significant interruption at the time of the guideline change resulting in a drop in the rate of women receiving screening and not merely a change in the trend over time. We also excluded women of other races due to small numbers for the race-specific analysis. For adequate statistical power, the ITS should have a minimum of 100 observations for each data point. When women of other race were included, many data points fell below this threshold.
This study is a first step in thoroughly evaluating screening for breast cancer. This study has not reported on how the updated Task Force screening recommendation has influenced breast cancer-related morbidity and mortality, nor has it addressed the costs of the guideline changes on the MHS. All of these issues are important next steps to further our interpretation of the findings presented here.
CONCLUSION
This study determined that the USPSTF breast cancer screening guidelines had small but statistically significant immediate and long-term effects for mammography utilization on women serving in active duty for the U.S. Military. No racial disparities were noted in this population with equal access to health care. The lack of DoD standard breast cancer screening guidelines was evident from the different patterns of mammography utilization observed among military branches. To completely understand the impact of the updated screening guidelines, future studies must incorporate research focusing on changes in breast cancer morbidity and mortality as well as updated cost-benefit analyses.
Funding
All phases of this study were supported by a grant from the U.S. Department of Defense, Defense Health Agency (award #HU0001-11-1-0023).
Conflict of Interest
None.
Contributor Information
Julie A Bytnar, Department of Preventive Medicine & Biostatistics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799.
Celia Byrne, Department of Preventive Medicine & Biostatistics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799.
Cara Olsen, Department of Preventive Medicine & Biostatistics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799.
Catherine T Witkop, Department of Preventive Medicine & Biostatistics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799.
Mary Beth Martin, Departments of Oncology and Biochemistry & Molecular and Cellular Biology, Georgetown University, E411 New Research Building, Washington, DC 20057.
Amanda Banaag, Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 4301 Jones Bridge Road, Bethesda, MD 20814-4799.
Tracey Koehlmoos, Department of Preventive Medicine & Biostatistics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799.
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