Geospatial Analysis of Access to Emergency Cesarean Delivery for Military and Civilian Populations in the US

IMPORTANCE Many women in the US, particularly those living in rural areas, have limited access to obstetric care. Military-civilian partnership could improve access to obstetric care and benefit military personnel, their civilian dependents, and the civilian population as a whole. OBJECTIVE To identify medical facilities within military and civilian geographic areas that present opportunities for military-civilian partnership in obstetric care and to assess whether civilian use of military medical treatment facilities (MTFs) could improve access to emergency cesarean delivery care in the US. DESIGN, SETTING, AND PARTICIPANTS This geospatial epidemiological population-based cross-sectional study was conducted from November 2020 to March 2021. ArcGIS Pro software, version 2.7 (Esri), was used to assess population coverage for TRICARE (military insurance) beneficiaries and civilianpopulationsandtoestimate30-minutetraveltimeto2392totalmilitaryandcivilianmedical facilities that were capable of providing emergency cesarean delivery care in the continental US. Data on health insurance coverage for TRICARE beneficiaries and their civilian dependents per county were obtained from the American Community Survey tables available through ArcGIS Pro software. Demographic characteristics of the general population were obtained from the 2020 key demographic indicators published by Esri. Race and ethnicity were not examined because the data used for this study were aggregated and did not include further categorization by race or ethnicity. MAIN OUTCOMES AND MEASURES Population coverage rates (measured in percentages) within 30-minute catchment areas, defined as areas that were within a 30-minute travel time to a medical facility capable of providing emergency cesarean delivery care. prioritized in the context of restructuring MTFs. This prioritization has the potential to improve access to emergency cesarean delivery care for underserved civilian populations in the US, particularly among those living in rural areas. This geospatial epidemiological population-based cross-sectional study was conducted from November 2020 to March 2021. The study assessed population coverage for female TRICARE beneficiaries (TRICARE functions as the health insurance program for the MHS) and civilians and estimated 30-minute travel time to 2392 total military and civilian medical facilities capable of providing emergency cesarean delivery care in the continental US. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cross-sectional studies. This study was approved by the Massachusetts General Brigham Institutional Review Board and deemed exempt from informed consent because it was not considered human participants research.

civilian populations and to estimate 30-minute travel time to 2392 total military and civilian medical facilities that were capable of providing emergency cesarean delivery care in the continental US. Data on health insurance coverage for TRICARE beneficiaries and their civilian dependents per county were obtained from the American Community Survey tables available through ArcGIS Pro software.
Demographic characteristics of the general population were obtained from the 2020 key demographic indicators published by Esri. Race and ethnicity were not examined because the data used for this study were aggregated and did not include further categorization by race or ethnicity.

MAIN OUTCOMES AND MEASURES Population coverage rates (measured in percentages) within
30-minute catchment areas, defined as areas that were within a 30-minute travel time to a medical facility capable of providing emergency cesarean delivery care.

RESULTS
A total of 29 MTFs and 2363 civilian hospitals capable of providing emergency cesarean delivery were identified across the contiguous US. Overall, an estimated 167 759 762 women (3 640 000 TRICARE beneficiaries and 164 119 762 civilians) were included in these service areas.
The analysis identified 17 of 29 MTFs (58.6%) capable of providing emergency cesarean delivery care that were located within 30-minute catchment areas. Of those, 3 MTFs were the only facilities capable of providing emergency cesarean delivery care within a 30-minute travel time in those regions, and 14 additional MTFs had catchment areas partially overlapping with civilian hospitals that also covered areas without alternative access to emergency cesarean delivery. Expanded use of these 14 MTFs could enhance access to emergency cesarean delivery care not otherwise covered by current civilian hospitals.
CONCLUSIONS AND RELEVANCE In this study, 58.6% of MTFs capable of providing emergency cesarean delivery care were located in areas with the potential to improve access to obstetric care within a 30-minute travel time. Maintenance of MTFs in these important access regions could be (continued)

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Introduction
More than 5 million women in the US live in 1085 of 3007 counties (36%) that do not have available obstetric care or obstetric clinicians (termed maternity care deserts), and an additional 10 million women live in counties with limited access to maternity care, defined as access to facilities, health care professionals, and insurance. 1 Geospatial analyses of obstetric care within the US reveal limited access to obstetric intensive care units (ICUs) for a substantial portion of the population. 2,3 Although 87% of women in the US live within 50 miles 4 of a facility providing level 3 obstetric care (ie, care for complex maternal and fetal conditions and complications) and neonatal intensive care, 5 only 61.6% of the population has timely emergency access (ie, within 30 minutes) to obstetric care, with even fewer having access to level 3 obstetric and neonatal care within 30 minutes. 2 Longer travel times to obtain obstetric care have been associated with worse perinatal outcomes, especially when there is a delay in the receipt of emergency cesarean delivery services. 6 Previous reports have highlighted gaps in obstetric coverage for patients in both the civilian and military health care systems. 2,7,8 The civilian health care system has substantial obstetric care disparities, with many women experiencing limited access to care, particularly in rural areas.
Although the American College of Obstetricians and Gynecologists has provided guidance to more effectively regionalize maternal care and improve access, 7 ongoing discussions of optimal staffing (ie, right-sizing) within the Military Health System (MHS) have the potential to reduce access to maternal care for military service members and their families owing to the closure or consolidation of military medical treatment facilities (MTFs) offering maternal care. 9,10 As a result, the Government Accountability Office has recommended that the MHS examine the capabilities of civilian hospitals that surround MTFs before making major changes. 11 Collaboration between military and civilian health care professionals has been a catalyst for medical innovation since the American Revolution. 12 In trauma care, military-civilian partnerships have allowed civilian surgeons to incorporate wartime advancements into their practices, and military surgeons have been able to maintain their surgical skills during military drawdowns and peacetimes. [13][14][15][16][17][18][19][20][21] Existing collaborations (such as those at major trauma centers in Baltimore, Maryland; Cincinnati, Ohio; Jacksonville, Florida; San Antonio, Texas; and Miami, Florida) provide successful models for such partnerships. 17,19,[22][23][24] However, there are opportunities to extend military-civilian collaborations beyond trauma care while addressing population health care needs in the US. One such opportunity includes the delivery of obstetric care, which represents an important area of need in the US civilian health care system and is also the largest service line within the MHS. In this context, it is important to examine how a successful partnership between the MHS and civilian hospitals could improve access to obstetric care and how this partnership would benefit military personnel, their civilian dependents, and the civilian population as a whole. This cross-sectional study sought to identify facilities within military and civilian geographic catchment areas that presented an opportunity for partnerships aimed at improving access to high-quality obstetric care, including emergency cesarean delivery capabilities. Military-civilian partnerships may improve access to cesarean delivery care, supporting the dual MHS aims of ensuring the clinical readiness of the military medical force and the medical readiness of the military force as a whole, particularly among service members living in rural communities. 25

Study Design
This geospatial epidemiological population-based cross-sectional study was conducted from November 2020 to March 2021. The study assessed population coverage for female TRICARE beneficiaries (TRICARE functions as the health insurance program for the MHS) and civilians and estimated 30-minute travel time to 2392 total military and civilian medical facilities capable of providing emergency cesarean delivery care in the continental US. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cross-sectional studies. This study was approved by the Massachusetts General Brigham Institutional Review Board and deemed exempt from informed consent because it was not considered human participants research.

Data Sources
We queried the TRICARE website 26 from November 16 to 20, 2020, to identify MTFs capable of providing emergency cesarean deliveries from all branches of service in the continental US. Capable MTFs were defined as those providing both obstetric and gynecologic services as well as emergency medical services. We then used their physical addresses to obtain geographic coordinates in Google Maps (Alphabet Inc). Data from the 2016 American Hospital Association annual survey 27 were used to identify nonmilitary medical facilities capable of providing emergency cesarean delivery. We excluded Hawaii and Alaska because of the substantial reliance on air transportation for medical care in those states. We defined civilian hospitals capable of providing emergency cesarean deliveries as those that had clinical service lines for obstetric and emergency care, at least 1 operating room, and at least 1 surgical admission. Geographic coordinates for non-MTFs were also obtained from the 2016 American Hospital Association survey. 27 We obtained data on health insurance coverage for TRICARE beneficiaries and their civilian dependents per county from the American Community Survey tables for 2017, which were available through ArcGIS Pro software, version 2.7 (Esri). 28 Demographic characteristics of the general population were obtained from 202 key demographic indicators published by Esri. 29 Age groupings for health insurance coverage categorized by data source did not allow us to ascertain the female population of childbearing age. We therefore aggregated female age groups (eg, 5-18 years, 19-34 years, and 34-64 years) to define the population of interest. Race and ethnicity were not examined because the data used for this study were aggregated and did not include further categorization by race or ethnicity.

Outcomes
The primary goals for this study were to (1) identify MTFs within 30-minute catchment areas (defined as areas that were within a 30-minute travel time to a medical facility capable of providing emergency cesarean delivery care based on recommendations from the American College of Obstetricians and Gynecologists regarding timely emergent cesarean delivery) 30 that were otherwise not served by civilian hospitals with emergency cesarean delivery capabilities; (2) estimate the proportion of female TRICARE beneficiaries who were dependent on MTF care for emergency cesarean deliveries (ie, no available civilian hospital within 30 minutes); and (3) estimate the proportion of the female civilian population who would gain access to emergency cesarean delivery services if MTFs in those important access areas were available to serve civilian populations. The secondary goal was to estimate the proportion of female TRICARE beneficiaries of childbearing age who did not have access to emergency cesarean delivery care within a 30-minute travel time.

Statistical Analysis
We used ArcGIS Pro software, version 2.7 (Esri), to estimate population coverage and 30-minute travel times to facilities capable of providing cesarean delivery care. We used the service area layer of the network analysis tool to generate 30-minute drive-time polygons to facilities capable of providing cesarean delivery care. The network analysis tool measured all feasible driving routes to the defined destination (ie, the medical facility) and based drive-time estimates on posted speed limits and existing traffic control devices. We then used the enrich layer of the business analysis tool to calculate population coverages of interest within each service area, and we used data management tools to calculate summary statistics and estimate the population without coverage.
We used SAS software, version 9.4 (SAS Institute Inc), and Excel software for Microsoft Office 365 (Microsoft Corp) to perform descriptive analyses and database management.

Results
We  Table 2). An additional 14 MTFs in 11 states (California, Colorado, Florida, Georgia, Louisiana, Mississippi, Missouri, Nevada, New York, North Carolina, and Washington) had catchment areas partially overlapping with civilian hospitals but also covered areas without alternative access to emergency cesarean delivery. These MTFs covered 158 768 TRICARE beneficiaries and had the potential to serve an additional 2 159 178 civilians within a 30-minute catchment area (Table 2).

Discussion
This cross-sectional study found that 58.6% of MTFs capable of providing emergency cesarean delivery were located in areas with the potential to improve access to emergency cesarean delivery care for civilians within a 30-minute travel time. These findings can be contextualized as follows: (1) these MTFs could be prioritized by the US Department of Defense, specifically when considering additional MTF reductions in access or scope of services during the ongoing MHS restructuring; and (2) these MTFs provide a distinct opportunity to explore additional military-civilian partnerships, which could increase access to emergency cesarean delivery care for TRICARE beneficiaries and underserved civilians living in rural areas.
In the MHS, federal regulations mandate that TRICARE beneficiaries have timely access to care and comprehensive obstetric coverage, including coverage for cesarean delivery. 8  A, Gray gradient reflects the population density of female TRICARE beneficiaries normalized by the total female population of TRICARE beneficiaries, with lighter gray representing lower density and darker gray representing higher density. B, Gray gradient reflects the population density of the female civilian population at the county level, with lighter gray representing lower density and darker gray representing higher density. In the US, the maternal mortality rate has increased over the past 10 years, from 15.7 pregnancyassociated deaths per 100 000 live births in 2006 to 16.9 pregnancy-associated deaths per 100 000 live births in 2016. 32 In addition, infant mortality rates in the US are higher compared with rates in other high-income countries. 33 As more rural hospitals close their obstetric units, women of childbearing age will likely experience increasingly limited access to obstetric care, including timely emergency cesarean deliveries. 34,35 Given increasing maternal morbidity and mortality in the US, decreasing access to obstetric care in rural areas may further exacerbate maternal morbidity and mortality as well as health care disparities in rural areas. Thus, it is important to examine and consider resources in the US maternal health care system as a whole. 7 The MHS has recently come under scrutiny for providing limited access to high-risk obstetric services and underperforming on certain performance outcomes, which has led the Government Accountability Office to request greater examination of civilian medical centers surrounding MTFs. 11  There has also been a call to expand access to MTFs to include Medicaid-eligible civilians in an effort to diversify the patient caseload of clinicians at MTFs and enable them to provide nontrauma care to civilian populations when deployed around the world. 40 An early example of this expansion in access was the implementation of the Collaborative Efforts Statement, Multi-Federal Cancer

Limitations
This study has several limitations. These are primarily associated with the study's ecological crosssectional design. In addition, although no standard cutoff exists for travel times as a measure of timely access to care, we selected a threshold of 30 minutes as a proxy for emergency travel time to estimate and define clear catchment areas. Furthermore, the data sources did not allow for the ideal categorization of women of childbearing age, despite the fact that those older than childbearing age are susceptible to other gynecologic emergencies and would likely benefit from access to emergency care similar to that addressed in this study. Because our estimations were calculated at the population level, individual-level associations may differ in direction and extent from group-level associations (ie, the associations may be subject to the ecological fallacy, which occurs when group characteristics are applied to individuals).

Conclusions
This cross-sectional study identified 17 MTFs that could improve access to high-quality cesarean delivery care for civilians in underserved regions of the US while also supporting military readiness.
This enhanced access to cesarean delivery care, particularly in rural areas, has the potential to reduce a These facilities also covered areas without alternative access to emergency cesarean delivery care.