2SFCA Method Research Articles

Enclave-Reinforced Inequality during the COVID-19 Pandemic: Evidence from University Campus Lockdowns in Wuhan, China

The COVID-19 pandemic has impacted urban life and created spatial and social inequalities in cities. The impacts of lifting full lockdown restrictions once fast-spreading and community-acquired infection waves were under control are still not fully understood. This study aims to explore spatial inequality reinforced in the intervals between the waves of infection during the COVID-19 pandemic. Enclave-reinforced inequality resulting from enclave-based lockdown policies in Chinese cities was investigated through an analysis of the impacts of university campus enclave closures on the accessibility and crowdedness of urban green spaces. Using a modified two-step floating catchment area (2SFCA) and inversed 2SFCA (i2SFCA) method, accessibility and crowdedness were calculated and compared under two different scenarios. Additionally, the Lorenz curve, Gini coefficient, and Theil index were used to measure and compare intra-city global and local inequalities under each scenario. The results indicate that the lockdown of university campus enclaves decreased the supply of urban green spaces. Campus closures not only exacerbated the unequal distribution of urban green space, but also reduced the inequality of crowdedness in urban parks due to increased crowdedness in parks near the closed enclaves. Moreover, both accessibility and crowdedness worsened when the calculations were weighted for population size and the total supply of green space. Enclave-based lockdown in cities reinforced spatial inequality, and it is highly complex and has multidimensional impacts on urban inequalities and environmental injustice which should be considered by urban planners and decision-makers hoping to create healthy, inclusive, resilient, and sustainable cities in the “new normal” of the COVID-19 pandemic.

How Phantom Networks, Provider Qualities, and Poverty Sway Medicaid Dental Care Access: A Geospatial Analysis of Manhattan.

Access to general dental care is essential for preventing and treating oral diseases. To ensure adequate spatial accessibility for the most vulnerable populations, New York State mandates a ratio of one general dentist to 2000 Medicaid recipients within 30 min of public transportation. This study employed geospatial methods to determine whether the requirement is met in Manhattan by verifying the online directories of ten New York managed care organizations (MCOs), which collectively presented 868 available dentists from 259 facilities. Our survey of 118 dental facilities representing 509 dentists revealed that significantly fewer dentists are available to treat Medicaid recipients compared to MCO directories. The average dentist-to-patient ratio derived from the MCO listings by the Two-Step Floating Catchment Area (2SFCA) method was 1:315, while the average verified ratio was only 1:1927. “Phantom networks”, or inaccurate provider listings, substantially overstated Medicaid dental accessibility. Surprisingly, our study also discovered additional Medicaid providers unlisted in any MCO directory, which we coined “hidden networks”. However, their inclusion was inconsequential to the overall dental supply. We further scrutinized dental care access by uniquely applying six “patient-centered characteristics”, and these criteria vastly reduced accessibility to an average ratio of merely 1:4587. Our novel evaluation of the spatial association between poverty, dental care access, and phantom networks suggests that Medicaid dental providers wish to be located in wealthier census tracts that are in proximity to impoverished areas for maximum profitability. Additionally, we discovered that poverty and phantom networks were positively correlated, and phantom providers masked a lack of dental care access for Medicaid recipients.

Use of 2SFCA Method to Identify and Analyze Spatial Access Disparities to Healthcare in Jeddah, Saudi Arabia

The issue of reducing spatial disparities in access to healthcare is one of the most important healthcare planning issues that policy makers and planners investigate and consider as a key focus until present time. A healthcare system that meets the requirements of availability and affordability will be useless if the spatial accessibility to healthcare is not provided to all equally. Therefore, this study aims to identify and analyze spatial disparities in access to healthcare centers in Jeddah, Saudi Arabia. The two-step floating catchment area (2SFCA) method was used to measure spatial accessibility of healthcare centers based on the travel time threshold (i.e., 30-min drive time in this study). The GIS technology was used to execute the 2SFCA method. A geodatabase, which includes the population districts, locations of healthcare centers, and road network, was created. Some procedures were performed within the road network database to set the travel time that is considered as an essential step to compute the origin–destination (OD) cost matrix. The OD matrix was later used as the source for calculating provider-to-population ratios and the spatial accessibility scores for population districts. The results of the study revealed spatial disparities in access to healthcare centers in Jeddah city. The majority of the Jeddah population (i.e., 97.51%) have accessibility to healthcare centers, but with disparate levels. The central districts have a higher access score compared to the rest of the city’s districts. Most districts that do not have accessibility to healthcare centers are concentrated in the southeast of the city. The results can help local health planners improve spatial equity in access to healthcare centers through giving the less-served districts a priority when allocating future healthcare centers in Jeddah city.

A narrative analysis of the 2SFCA and i2SFCA methods

ABSTRACT This study examines the narrative(s) that surround the development of the Two-Step Floating Catchment Area (2SFCA) family of GIS-based accessibility statistics. It identifies what has been omitted from the pre-GIS era in its discourse and presents a parallel but alternative narrative behind these statistics. The results suggest that the ‘crowdedness’ metric from the i2SFCA can more broadly be viewed as a form of market potential, and the 2SFCA and i2SFCA are normalized, singly supply-constrained and singly demand-constrained spatial interaction models, respectively. It postulates that the values calculated in the 2SFCA are not real supply-to-population ratios, but the inverse of the market potential metric associated with the i2SFCA is, and this inverse value can be used to develop an adjusted supply accessibility metric. This enables the 2SFCA family of supply accessibility metrics also to account for congestion at service sites. Results using the adjusted and congested supply accessibility metrics suggest that less densely populated areas may not be at a disadvantage with respect to the supply of services once congestion is taken into account. The adjusted and congested supply accessibility metrics also have a complementary cost accessibility metric that when used in tandem measure the size and efficiency of supply availability.

Assessing the Impacts of Hierarchical Healthcare System on the Accessibility and Spatial Equality of Healthcare Services in Shenzhen, China

The hierarchical healthcare system is widely considered to be a desirable mode of the delivery of healthcare services. It is expected that the establishment of a hierarchical healthcare system can help provide better and more equal healthcare accessibility. However, limited evidence has been provided on the impacts of a hierarchical healthcare system on healthcare accessibility. This study develops an improved Hierarchical two-step floating catchment area (2SFCA) method, which incorporates variable catchment area sizes, distance friction effects and utilization efficiency for facilities at different levels. Leveraging the Hierarchical 2SFCA method, various scenarios are set up to assess the accessibility impacts of a hierarchical healthcare system. The methods are applied in a case study of Shenzhen. The results reveal significant disparity and inequality in healthcare accessibility and also differences between various facility levels in Shenzhen. The overall healthcare accessibility and its equality can be significantly improved by fully utilizing existing facilities. It is also demonstrated that allocating additional supply to lower-level facilities can generate larger accessibility gains. Furthermore, allocating new supply to primary facilities would mitigate the inequality in healthcare accessibility, whereas inequality tends to be aggravated with new supply allocated to tertiary facilities. These impacts cannot be captured by traditional accessibility measures. This study demonstrates the pivotal role of primary facilities in the hierarchical healthcare system. It can contribute to the literature by providing transferable methods and procedures for measuring hierarchical healthcare accessibility and assessing accessibility impacts of a hierarchical healthcare system in developing countries.

SAR-Gi*: Taking a spatial approach to understand food deserts and food swamps

Most existing food deserts/swamps studies adopted non-spatial approaches,overlooking the role of spatial dependence in the associations between food access and socioeconomic status. This study aims to fill the gap by examining this relationship with a spatial perspective. Using Austin, Tx as a case study, we adopted a multi-mode Huff-based 2SFCA method to measure the spatial access to food stores. Eight socioeconomic variables were represented by two indices per factor analysis:Economic Deprivation Index (EDI) and Sociocultural Deprivation Index (SDI). We proposed a SAR-Gi* model to characterize food deserts/swamps in Austin. Our analyses reveal that EDI is a significant predictor for access to healthy food (β = -0.054, p = 0.037), and SDI is significantly associated with access to unhealthy food (β= 0.160, p = 0.000). We also found that food deserts and swamps in Austin are concentrated in the east and northeast of Austin, respectively. The noticeable difference between the spatial patterns of food deserts and food swamps as identified by our study and those based on the USDA definition or other traditional methods speaks to the great potential of the SAR-Gi* model in reflecting geographical patterns and relations embedded in food access and socioeconomic status of neighborhoods.

Different configurations of the two-step floating catchment area method for measuring the spatial accessibility to hospitals for people living with disability: a cross-sectional study

BackgroundPoor spatial accessibility to hospital services is associated with higher morbidity and mortality rates among people living with disability. Improved methods to evaluate spatial accessibility are needed. This study measured the potential spatial accessibility of people living with disability by applying four configurations of the two-step floating catchment area (2SFCA) method to recommend the best model for use in health services research.Methods2SFCA and an enhanced version (E2SFCA) were used to measure hospital accessibility for people living with disability. We also developed and embedded a non-spatial severity index into the two 2SFCA models. We used 16,186 records of people living with disability experience to evaluate the methodological performance across 68 neighbourhoods of the city of Ahvaz, located in south-western Iran. The models’ performance were measured through correlation of the four accessibility scores with the distance to closest hospital for each neighbourhood centroid.ResultsAmong the four models used to measure spatial accessibility, the E2SFCA integrated with the severity index displayed the best performance. Most people with disabilities lived in neighbourhoods located in the South-western and central areas of the city. Interestingly, south-western neighbourhoods had poor hospital accessibility score and were identified as unmet need areas for access to health services.ConclusionsInclusion of the severity factor in the E2SFCA improved access measurements. Identifying areas with poor levels of hospital accessibility can help policymakers design tailored interventions and improve accessibility to hospital-based care in urban settings for people living with disability.

Measuring accessibility to health care services for older bus passengers: A finer spatial resolution

Health care accessibility is a vital indicator for evaluating areas where there are medical shortages. However, due to the lack of population data with a satisfactory spatial resolution, efforts to accurately measure health care accessibility among older individuals have been hampered to some extent. To address this issue, we attempt to measure accessibility to health care services for older bus passengers in Nanjing, China, using a finer spatial resolution. More specifically, based on one month's worth of bus smart card data, a framework for identifying the home stations (i.e., a passenger's preferred station near their residence) of older passengers is developed to measure the aggregate demand at the bus stop scale. On this basis, a measurement that integrates the Gaussian two-step floating catchment area (2SFCA) and the adjusted 2SFCA methods (referred to as the adjusted Gaussian 2SFCA method) is proposed to measure accessibility to health care services for older people. The results show that: (1) almost all home stations experience inflated demand, especially those located in the suburbs; (2) despite abundant health care resources, home stations in urban districts are rarely identified as high accessibility stations, due to high demand densities among the older population; and (3) more attention should be paid to two types of home stations – those with a medical institution and those with bed shortages, respectively. The first type is predominantly distributed in the periphery of the city, in the suburbs where the travel time required to access the nearest health care service by bus is longer. The second type is mostly located in the outskirts of urban districts and in the central area of one suburb. These findings could help policy makers to implement more appropriate measures to design and reallocate health care resources.

Facility Attractiveness and Social Vulnerability Impacts on Spatial Accessibility to Opioid Treatment Programs in South Carolina.

Opioid dependence and opioid-related mortality have been increasing in recent years in the United States. Available and accessible treatments may result in a reduction of opioid-related mortality. This work describes the geographic variation of spatial accessibility to opioid treatment programs (OTPs) and identifies areas with poor access to care in South Carolina. The study develops a new index of access that builds on the two-step floating catchment area (2SFCA) method, and has three dimensions: a facility attractiveness index, defined by services rendered incorporated into the Huff Model; a facility catchment area, defined as a function of facility attractiveness to account for variable catchment size; and a Social Vulnerability Index (SVI) to account for nonspatial factors that mitigate or compound the impacts of spatial access to care. Results of the study indicate a significant variation in access to OTPs statewide. Spatial access to OTPs is low across the entire state except for in a limited number of metropolitan areas. The majority of the population with low access (85%) live in areas with a moderate-to-high levels of social vulnerability. This research provides more realistic estimates of access to care and aims to assist policymakers in better targeting disadvantaged areas for OTP program expansion and resource allocation.

Spatial accessibility assessment of COVID-19 patients to healthcare facilities: A case study of Florida

During the COVID-19 pandemic, healthcare facilities worldwide have been overwhelmed by the amount of coronavirus patients needed to be served. Similarly, the U.S. also experienced a shortage of healthcare resources, which led to a reduction in the efficiency of the whole healthcare system. In order to evaluate this from a transportation perspective, it is critical to understand the extent to which healthcare facilities with intensive care unit (ICU) beds are available in both urban and rural areas. As such, this study aims to assess the spatial accessibility of COVID-19 patients to healthcare facilities in the State of Florida. For this purpose, two methods were used: the two-step floating catchment area (2SFCA) and the enhanced two-step floating catchment area (E2SFCA). These methods were applied to identify the high and low access areas in the entire state. Furthermore, a metric, namely the Accessibility Ratio Difference (ARD), was developed to evaluate the spatial access difference between the models. Results revealed that many areas in the northwest and southern Florida have lower access compared to other locations. The residents in central Florida (e.g., Tampa and Orlando cities) had the highest level of accessibility given their higher access ratios. We also observed that the 2SFCA method overestimates the accessibility in the areas with a lower number of ICU beds due to the “equal access” assumption of the population within the catchment area. The findings of this study can provide valuable insights and information for state officials and decision makers in the field of public health.

Using the variable two-step floating catchment area method to measure the potential spatial accessibility of urban emergency shelters

As a public service facility that provides relief, resettlement, and evacuation services to disaster-affected people, emergency shelters play a vital role in helping people cope with disaster events. The measurement of spatial accessibility of existing emergency shelters is a key task in improving emergency shelter services and minimizing property losses and deaths. In this study, considering the differences in emergency shelters’ service capacities and population distribution, we developed a two-step floating catchment area (2SFCA) method with a variable service radius and evacuation radius to describe emergency shelter accessibility in Lanzhou’s core area and compared with the traditional 2SFCA method. Furthermore, we used bivariate local Moran's I to identify the spatial relationships between emergency shelter accessibility and population density. The results show that the traditional 2SFCA method underestimates accessibility in densely populated areas with dispersed emergency shelters. Shelter accessibility in Lanzhou’s core area is unevenly distributed, with the lowest levels of accessibility in densely populated areas. There is an obvious spatial mismatch between the accessibility of emergency shelters and the population density, and the central and western part of Chengguan has a serious shortage of emergency shelters. This study provides important information for the planning and construction of emergency shelters.

Analysis of urban green space accessibility and distribution inequity in the City of Chicago

Urban green space (UGS) has positive impacts on people’s physical and mental health. Equal access to UGS for all people, regardless of their individual characteristics, is key to the achievement of better public health outcomes. Existing studies have focused largely on inequity in spatial UGS accessibility distribution but failed to uncover the disparities of UGS accessibility among different racial/ethnic and income groups as well as inequity in income-based UGS accessibility distribution within the same racial/ethnic groups. By using the city of Chicago as the study area, we adopt the two-step floating catchment area (2SFCA) method to measure census tract-level UGS accessibility and compare distribution disparities among white-majority, black-majority and Hispanic-majority census tracts as well as low-income and non-low-income census tracts. In addition, we employ the Palma ratio to measure the income-based UGS accessibility distribution inequity within respective racial/ethnic groups. The results show that white-majority census tracts generally enjoy significantly better UGS accessibility than minority-dominated census tracts, while black-majority census tracts have higher UGS accessibility than Hispanic-majority census tracts. In terms of the intra-racial/ethnic income-based UGS accessibility inequity between the richest and the poorest, inequity is the lowest among white-majority census tracts and the highest among black-majority census tracts, with inequity in Hispanic-majority census tracts in the intermediate range.

Spatial access to health care: a case study on community health centers in Asmat District, Papua, Indonesia.

In recent decades, access to primary health care has become a crucial issue for health policy planners and researchers. One of the fundamental problems is inequitable access to health care due to imbalanced resource distributions between health care providers and population location. Accordingly, this study aims to examine the spatial access to Community Health Centers (CHC) in the Asmat district, one of the most isolated regions in Papua, Indonesia. We conducted the study using a two-step floating catchment area (2SFCA) method to quantify accessibility value to primary health care of each village in the district of Asmat. By taking five distance thresholds ranging from 5 to 25km with an increment of 5km, the results indicate that distance has a varying impact on each village. For example, within a 5-km distance threshold, 74% of villages have a zero score or have no access to CHCs, 22% have a score < 100, while only 4% of villages have a score > 100 or meet the minimum score recommended by World Health Organization (WHO). Two major related factors of these geographic disparities are the unequal distribution of CHCs and the high population dispersion. As an attempt to provide equal access to health care services, these results suggest that spatial access should be conscientiously considered by health planners and policy makers.

An integrative method for analyzing spatial accessibility in the hierarchical diagnosis and treatment system in China.

Spatial accessibility to medical services (SAMS) is one of the most important indicators to examine the convenience for people to get access to medical services. In China, the difficulty in getting access to medical services is a commonly appreciated social problem. To mitigate this problem, Chinese government established the hierarchical diagnosis and treatment system (HDTS) in 2005. However, there is no existing study to examine the HDTS from the perspective of SAMS. This paper therefore introduces an integrative method to analyze SAMS in adopting HDTS. The introduced integrative method is developed by referring to the existing 2SFCA method, a commonly applied method for analyzing SAMS, and the characteristics of HDTS are taken into consideration. The application of the integrative method is demonstrated with reference to a Chongqing case. The research findings suggest that: 1) A new method to evaluate SAMS in the context of HDTS is needed; 2) The integrative method developed in this study is proven effective for analyzing SAMS in the context of HDTS through the case study; 3) The case results reveal that the implementation of HDTS can significantly improve the overall SAMS performance in Chongqing; 4) The desirable referral rate of HDTS is 1.24% in the case study by comparing the SAMS performance between different referral rates.

Urban Public Green Space Equity against the Context of High-Speed Urbanization in Wuhan, Central China

This study examines the relationship between equity of public green space and urban expansion/sprawl under high-speed urbanization. Equity of urban public green space indicates the degree to which urban public green spaces are distributed spatially in an equal way, with regard to the spatial variation of residents’ “need” for green space. In emerging economies such as China, especially in developing or underdeveloped cities such as Wuhan, central China, rapid urban growth challenges the capacity of the state to provide infrastructure and services for its urbanites equally. In order to research the relationship between industrial development and green space equity under the background of rapid urbanization, the use of quantitative methods to more accurately measure the degree of spatial inequality is essential. In this study, the accessibility of urban public green space in Wuhan is examined based on the two-step floating catchment area method (2SFCA) method at multilevel radius; the urban public green space accessibility of Wuhan in 2013 and 2016 are acquired, and the link between changes in accessibility of urban public green spaces and urban expansion in Wuhan is discussed. It is found that industrial development takes precedence over green space. With its vigorous development, industrial land attracts increasing population, resulting in the drastic decline of the service capacity of green spaces, which is not conducive to the long-term development of the city.

How to Find Vacant Green Space in the Process of Urban Park Planning: Case Study in Ningbo (China).

Nature-based recreation in urban areas is essential for the well-being of citizens. Park green space (PGS) is a necessary urban infrastructure and a critical step of urban planning and policy-making. The existing research on PGS only focuses on service allocation problems existing in the current urban development, ignoring changes in residential communities accessibility. This research provides new ideas to evaluate PGS. Based on parks and residential communities’ data, we adopt an improved Gaussian-based two-step floating catchment area (2SFCA) method to evaluate PGS accessibility in Ningbo (China) and its matching with different levels of residential areas. We present a case study in Ningbo, and discuss its implications for PGS management. This study contains two elements: (a) Compare the current and initial PGS accessibility of each community to accurately identify the communities with PGS vacancies. (b) Analyze and discuss the association between community accessibility and residential house prices. Compare the PGS coverage ratios of communities at different levels to determine the equity of PGS planning in Ningbo. We found that the level of PGS allocation in the central area of Ningbo is high. Obviously, high-value clusters are formed in Sanjiangkou, Zhenhai New Town, Southern and Eastern Yinzhou. The accessibility level in the middle area of Yinzhou is low, and there are super high accessibility residential communities in the outer city area. There is an exact period of green space vacancy in the middle and the outer area. The residential areas with ultra-high accessibility did not configure PGS services at the beginning of their construction. There is no noticeable difference in PGS accessibility of residential communities of different levels at present, but 149 low- and middle-income residential communities lack green space service when the construction was completed. High-end residential communities have priority on enjoying park green space services. Our study suggests that PGS accessibility should be studied temporally and spatially for each residential community. The Ningbo government should strengthen the balanced construction of green space in parks and guarantee green space services for low-end residential communities to improve green space equity.

Facility Centers in Rural Areas: Concept, Development, Effect on Habitational Accessibility and Facility Crowdedness, and Policy Strategies for Resource Allocation

This article discusses the concept of facility center development by identifying locations for colocating multiple facility types so as to access several facilities at a single location. This concept maximizes accessibility and reduces travel costs for individuals with multiple trip purposes. The appropriateness of facility center locations are evaluated with two parameters: (1) habitation accessibility to facility centers using the two-step-floating-catchment-area (2SFCA), method, and (2) facility center crowdedness using the inverted two-step-floating-catchment-area (i2SFCA) method. This study uses both 2SFCA and i2SFCA methods concurrently to get perception of quality of service provided and received. Considering two facilities such as a health care center and a high school for spatial planning of facility centers, the proposed methodology is analyzed for two cases. In the first case, it is assumed that no facility exists in the study area and in the second case, the existing locations of health care centers and high schools are considered for analysis. The proposed methodology is applied in Jhunjhunu—a district in Rajasthan, India—as a case study. The discussed policy strategy would help with resource allocation in a phased manner for new facility development or capacity augmentation of existing facilities, and thus would improve the quality of rural citizens’ lives.

Spatial Access by Public Transport and Likelihood of Healthcare Consultations at Hospitals

As healthcare is a right in Canada, analyzing the distribution of spatial access to medical consultations, which are crucial for the prevention, diagnosis, and early treatment of illnesses, is fundamental to understanding health equity. Spatial accessibility can influence whether individuals can reasonably reach the services they seek. However, as an indicator of potential access, it does not guarantee realized access because of predisposing and need factors. This study examines the relationship between spatial accessibility to hospitals and the likelihood of consulting with a healthcare professional at a hospital in eight Canadian metropolitan regions while controlling for individual characteristics through multilevel regression modeling. Spatial accessibility was computed using the two-step floating catchment area (2SFCA) method. Self-reported consultations and socio-demographic characteristics were obtained from the Canadian Community Health Survey. We found that the likelihood of consultations differed between genders (female OR: 1.133, CI: 1.023–1.255; compared with male) and followed a positive household income gradient (high-income OR: 1.236, CI: 1.094–1.397; middle-income OR: 1.039, CI: 0.922–1.172; compared with low-income), but is not influenced by age. Living in areas with higher spatial accessibility was positively linked to consultations (OR: 1.014, CI: 1.000–1.028), even after controlling for perceived health (OR: 0.540, CI: 0.471–0.621), chronic conditions (OR: 1.738, CI: 1.587–1.904), and having a regular doctor (OR: 1.313, CI: 1.187–1.452). Policies that may improve spatial accessibility to healthcare services through increasing supply, managing demand, and enhancing level of public transport service should be considered to improve individuals’ ability to consult healthcare professionals, potentially leading to better health outcomes.

Hierarchical two-step floating catchment area (2SFCA) method: measuring the spatial accessibility to hierarchical healthcare facilities in Shenzhen, China

BackgroundSpatial accessibility to healthcare facilities has drawn much attention in health geography. In China, central and local governments have aimed to develop a well-organized hierarchical system of healthcare facilities in recent years. However, few studies have focused on the measurement of healthcare accessibility in a hierarchical service delivery system, which is crucial for the assessment and implementation of such strategies.MethodsBased on recent improvements in 2SFCA (two-step floating catchment area) method, this study aims to propose a Hierarchical 2SFCA (H2SFCA) method for measuring spatial accessibility to hierarchical facilities. The method considers the varied catchment area sizes, distance decay effects, and transport modes for facilities at various levels. Moreover, both the relative and absolute distance effects are incorporated into the accessibility measurement.ResultsThe method is applied and tested in a case study of hierarchical healthcare facilities in Shenzhen, China. The results reveal that the general spatial accessibility to hierarchical healthcare facilities in Shenzhen is unevenly distributed and concentrated. The disparity of general accessibility is largely caused by the concentrated distribution of tertiary hospitals. For facilities at higher levels, average accessibility of demanders is higher, but there are also larger disparities in spatial accessibility. The comparison between H2SFCA and traditional methods reveals that traditional methods underestimate the spatial disparity of accessibility, which may lead to biased suggestions for policy making.ConclusionsThe results suggest that the supply of healthcare resources at primary facilities is far from sufficient. To improve the spatial equity in spatial accessibility to hierarchical healthcare facilities, various actions are needed at different levels. The proposed H2SFCA method contributes to the modelling of spatial accessibility to hierarchical healthcare facilities in China and similar environments where the referral system has not been well designed. It can also act as the foundation for developing more comprehensive measures in future studies.

Spatial accessibility to colonoscopy and its role in predicting late-stage colorectal cancer.

ObjectiveTo better determine the relationship between spatial access to colonoscopy and colorectal cancer (CRC) outcomes, our objective was to examine the agreement of the classic, enhanced, and variable two‐step floating catchment area (2SFCA) methods in evaluating spatial access to colonoscopy and to compare the predictive validity of each method related to late‐stage CRC. 2SFCA methods simultaneously consider supply/demand of services and impedance (ie, travel time).Data SourcesColonoscopy provider locations were obtained from the South Carolina Ambulatory Surgery Database. ZIP code tabulation area (ZCTA) level population estimates and area‐level poverty level were obtained from the American Community Survey. Rurality was determined by the United States Department of Agriculture's Rural‐Urban Commuting Area codes. Individual‐level CRC data were obtained from the South Carolina Central Cancer Registry.Study DesignUsing the classic, enhanced, and variable 2SFCA methods, we calculated ZCTA‐level spatial access to colonoscopy. We assessed agreement between the three methods by calculating Spearman's rank coefficients and weighted Kappas (Κ). Global and Local Moran's I were used to assess spatial clustering of accessibility scores across 2SFCA methods. We performed multilevel logistic regression analyses to examine the association between spatial accessibility to colonoscopy, area‐ and individual‐level factors, and late‐stage CRC.Principal FindingsWe found strong agreement (Weighted Κ = 0.82; 95% CI = 0.79‐0.86) and identified similar clustering patterns with the classic and enhanced 2SFCA methods. There was negligible agreement among the classic/enhanced 2SFCA and the variable 2SFCA. Across all 2SFCA methods, regression models showed that spatial access to colonoscopy, rurality, and poverty level were not associated with greater odds of late‐stage CRC, though Black race was associated with late‐stage CRC across all models.ConclusionsNone of the 2SFCA methods showed an association with late‐stage CRC. Future studies should explore which elements (spatial or nonspatial) of access to care have the greatest impact on CRC outcomes.