J Community Health (2008) 33:444–448 DOI 10.1007/s10900-008-9112-x
ORIGINAL PAPER
Spatial Accessibility to Pediatric Services Fabiana Cervigni Æ Yoichi Suzuki Æ Takuma Ishii Æ Akira Hata
Published online: 26 June 2008 Ó Springer Science+Business Media, LLC 2008
Abstract The objective of this study was to assess spatial accessibility (SA) to pediatric healthcare services at hospitals in Chiba Prefecture, Japan in 2006. We considered the distribution of general pediatricians and neonatologists relative to the geographical distribution of children using the two-step floating catchment area method, which accounts for the pediatrician-to-children ratios within catchment areas with defined travel distance (TD) thresholds. All measurements were carried out within a geographic information system. We found varied growth rate trends of children within the 61 municipalities of Chiba Prefecture between 1995 and 2006. The eastern and southern areas of the prefecture were less populated and had a small number of children in contrast to the central and northwestern areas, which had higher density of child population, less negative growth rates and even positive growth rate trends in some municipalities. For neonatology services, we used the number of live births (LB) and low birth weight (LBW) infants as populations. Lower LBW rates were found within the northern area while higher LBW rates were found within the southern area (minimum, 3.1%; maximum, 18.4%). The average LBW rate was 9.0% in Chiba Prefecture, whereas it was 9.5% for all Japan in 2005. SA analysis showed that 98.8% of children distributed within a 10 km TD threshold from a hospital with general pediatric services, and that 82.3% of LB and LBW distributed within a 30 km TD threshold from a hospital with neonatology services. The distribution of pediatricians relative to the population they serve was not homogeneous at local level. Through the methodology applied, we F. Cervigni (&) Y. Suzuki T. Ishii A. Hata Department of Public Health, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chiba 260-8670, Japan e-mail:
[email protected]
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visualized areas short of pediatric services. The assessment of SA at local level provided informative results to achieve social equity in hospital access. The practical implications of this study are the need for reliable data for research purposes and policy development for children. Keywords Children Pediatric services Neonatology Spatial accessibility Geographic information system
Introduction In Japan, the shortage of pediatricians and specialized pediatric services has recently been comprehensively discussed in relation to the increasing demand for these services, losses in revenue and working condition problems [1–8]. Despite the fact that the pediatric workforce shortage at hospitals is one of the main concerns of Japanese medical services, the geographic distribution of pediatricians relative to children remains insufficiently assessed. Matsuo et al. [5] argued that the informative data related to the current supply and practice of pediatricians (their availability, distribution and overlapped work) is not sufficient to address children health care needs. They also highlighted the lack of researchers in Japan specializing in the study of health care policy for children in contrast to the large number of researchers specializing in the study of health policy for the elderly [5]. The objective of this study was to address the issue of local availability of services by examining the distribution of general pediatricians and neonatologists relative to the geographical distribution of the population they serve. We conducted analysis on spatial accessibility (SA), focusing on the shortest travel distance (TD) between population and services through city streets and the availability of
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pediatricians. In this context, we used the two-step floating catchment area (FCA) method [9] to overcome the limitation of the simple assessment of pediatrician-to-children ratios at municipality level. With this method, accessibility to pediatric services was assessed by calculating pediatrician-to-children ratios within hospital catchment areas regardless of city boundaries. Results show areas short of pediatric services as well as over-served areas based on the population and service locations. One contribution of this paper is its focus on child population growth and geographic distribution at local level for pediatric services assessment. The population of Chiba Prefecture is one of the wealthiest in Japan due to the prefecture’s strong commercial and industrial sectors. The northwestern area of the prefecture extends to the urban agglomeration of Tokyo and Saitama and it is where the majority of the total population, children and pediatricians working at hospitals are concentrated. We observed different trends of child population growth at municipality level. Although municipalities in the southern and eastern areas showed significantly decreasing numbers of children, some municipalities in the northwestern area showed increasing trends. To assess SA within a geographic information system (GIS), we required three main data layers: population location, pediatrician location and city street. Updated data on population by age in municipalities were obtained from the Statistics Bureau [10]. On the contrary, there was no available data on pediatric services by specialty and place of work (although there is an annual survey on the distribution of medical, odontological and pharmaceutical services). Digital cartographic data are readily available in Japan.
Data We used a population under 15 years of age from 1995 to 2006 (population census) for assessing child population trends and SA in 2006. For assessing accessibility to neonatology services, we used the numbers of live births (LB) and low birth weight (LBW) infants (those weighting less than 2,500 g) as populations. We also assessed the geographical distribution of neonatal deaths (ND) (deaths occurring within the first 4 weeks) and early neonatal deaths (END) (deaths occurring within the first week of life). Data on LB, LBW, ND and END were obtained from the vital statistics records [11]. We considered the administrative division of municipalities used by the Statistics Bureau [12] in 2006 to locate populations. Sixty-one population centroids represented children at municipalities (6 wards in Chiba City; 35 cities;
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Fig. 1 Geographic distribution of children density in Chiba Prefecture
17 towns and 3 villages). In 2006, the population in these municipalities ranged from 6,859 to 579,235 residents (755–78,035 children), while the total population in the prefecture reached 6,134,039 residents (832,237 children). The areas covered by these municipalities ranged from 17.29 to 368.2 km2 and the population density ranged from 10 to 1,456 children/km2 (Fig. 1). The most populous zone was the northwestern area of the prefecture extending next to Tokyo and Saitama. In Chiba Prefecture in 2006, there were 93 hospitals (with 393 pediatricians) to meet general pediatric demand and 7 hospitals with pediatric neonatologists for neonatology services (in this study, we included only pediatricians holding board specialization). Information about hospitals with pediatric services was obtained from hospital records in Chiba Prefecture in 2006 and the number of practicing pediatricians was obtained from the local government of the Prefecture. Digital data on city streets was obtained from Digital Map 2500 (Japan Map Center) [13].
Methodology Data on population, hospital and city street locations were stored and displayed by GIS. Using the ‘‘Accessibility Measures Program’’ [14], we constructed a geometric network to join populations to facilities through road segments, and TD between them was calculated through the city streets. To assess the availability of general pediatric services, we used the two-step FCA method that generates pediatrician-to-population scores within hospitals and population centroid catchment areas. In the first step of this method,
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we created 10 km TD catchment areas for every hospital, and then calculated the pediatrician-to-children ratios for these areas and assigned these ratios to the facilities. In the second step, we centered the 10 km TD catchment areas at child population centroids and searched for all hospitals falling within these areas. When 2 or more hospitals fell within the population catchment area, we summed the pediatrician-to-children ratios assigned to the facilities (generated in the first step) as the SA score for each population area (detailed information on this method is described by Luo and Wang [9]). Here, we present the results as the number of children per pediatrician for ease of understanding and interpretation. Spatial accessibility was classified to 3 areas according to the number of children per pediatrician as follows: high, medium and low SA areas. High SA areas had 2,000 or fewer children per pediatrician (we established this limit because the regional ratio for Chiba Prefecture was 2,117:1 children per pediatrician), medium SA areas had 2,000– 4,000 children per pediatrician and low SA areas had more than 4,000 children per pediatrician. For neonatology services, we considered high SA areas (those with 5,000 [500] or fewer LB [LBW] per specialist), medium SA areas (those with 5,001–10,000 [501–1,000] LB [LBW] per specialist) and low SA areas (those with 10,001–15,000 [1,001–1,400] LB [LBW] per specialist) within a catchment area of 30 km TD.
Results General Pediatric Services Although we found a general matching of pediatricians and children, the analysis using the two-step FCA method revealed some areas short of pediatric services at hospitals in Chiba Prefecture in 2006. Analysis of availability of general pediatric services at hospitals showed that the regional ratio of children per pediatrician (2,117:1) in Chiba Prefecture in 2006 was not always homogeneous at local level. We found that almost all children (98.8%) distributed within areas with shorter TD or located 10 km from a hospital with general pediatric services. Availability of general pediatric services within these areas showed that 16.3% (135,974) of children located within high SA areas, with 2,000 or fewer children per pediatrician; 56.8% (472,695) of children located within medium SA areas with 2,001–4,000 children per pediatrician and 25.7% (213,956) of children located within low SA areas with 4,000 or more children per pediatrician (Fig. 2). Municipalities with hospitals beyond the catchment area of 10 km TD from a hospital with general pediatric services
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Fig. 2 Geographic distribution of SA to general pediatric services in Chiba Prefecture
included only 6 towns. The populations in these towns represented 1.2% (9,612 children) of the total child population in Chiba Prefecture in 2006 (in all these municipalities, child population showed decreased growth rates from 1995 to 2006). Neonatology The rate of LBW in Japan has been increasing to date [15–17], and Chiba Prefecture which has a lower rate is following the same trend (Fig. 3). In 2005, the LBW rates (LB/LBW 9 100) were 9.5% for all Japan and 9.0% for Chiba Prefecture. Within Chiba Prefecture, we found that the municipality with the minimum LBW rate of 3.1% was located in the northern area and the municipality with the maximum LBW rate of 18.4% was located in the southern area. Figure 4 shows the geographical distribution of LBW rates at municipal level. We measured the distribution of LB, LBW infants, ND and END occurring within the distance thresholds of 10, 10–20, 20–30 and more than 30 km TD. We found a
Fig. 3 Low birth weight rates trends in Japan and Chiba Prefecture
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Fig. 4 Geographic distribution of low birth weight rates within Chiba Prefecture
Fig. 6 Geographic distribution of SA to neonatology services in Chiba Prefecture
similar distribution of LB and LBW within all areas and a higher amount of both within 10 and 20 km TDs (Fig. 5). ND and END occurrence distributed proportionally and similarly within the 10 and 20 km TD thresholds, but the proportion of END increased for larger TD thresholds. However, the numbers of both were small within all municipalities in Chiba Prefecture. The numbers of LB and LBW infants also distributed geographically and proportionally. In Chiba Prefecture in 2005, the total numbers of LB, LBW, ND and END were 50,588, 4,551, 76 and 54, respectively. Figure 6 shows the distribution of SA areas for neonatology services within a 30 km TD threshold. The availability of neonatology services seems to be higher within the southern and central areas, but lower within the northwestern and central eastern areas of the prefecture. We found that most of the northeastern areas and a few other municipalities were located outside the 30 km TD catchment areas. Regarding LB and LBW in 2006, 8% located within the high SA areas, 21% located within the medium SA areas, 53% located within the low SA areas and 18% located outside the catchment areas.
Discussion
Fig. 5 Percentages of live births, low birth weight infants, neonatal deaths and early neonatal deaths within areas located: less than 10, 10–20, 20–30 and beyond 30 km travel distance from a hospital with neonatology services in Chiba Prefecture
From our analysis on the distribution of pediatric healthcare services relative to children, we could visualize that only a few areas were located beyond the 10 km TD from a hospital with general pediatric services in Chiba Prefecture in 2006. These areas had both small numbers and decreasing growth rates of children from 1995 to 2006. Regarding the availability of general pediatric services, areas considered as lower SA involved one quarter of the children and showed various geographic distributions and demographic trends. Populations living within these areas shared 1 pediatrician among 4,000 children or more. These municipalities have to be considered in order to enhance SA by increasing the number of pediatricians in hospitals where pediatric services already exist. Medium to high SA levels entail the majority of children. These areas had an average pediatrician-to-children ratio (1:2,149) nearly similar to that found at the prefectural level (1:2,117). These areas included most of the municipalities with increasing trends in the number of children and were mainly located next to the most densely populated areas at the northwestern area of the prefecture. Differences in SA could be used to regulate the distribution of pediatricians in relation to children. The results imply that high SA indicates not only better SA but also an excessive number of pediatricians within the area. Medium SA would be our target children-to-pediatrician ratio to achieve social equity of access to pediatric services. Low SA implies the need to increase the number of pediatricians within the area, while outside the catchment areas implies the need to reduce the distance between population and services. For neonatology services, we found that municipalities with better SA were located within the southeastern and southwestern areas, where higher LBW rates were also
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found. Medium SA located within the central area with relative medium LBW rates, and lower SA located within the northwestern area where some high LBW were also found. Throughout this study, we focused on visualizing demographic trends within Chiba Prefecture. Over the last few years, the number of children in the eastern and southern areas has significantly decreased in contrast to the central and northwestern areas of the prefecture. A study on population projection at local level would help in the distribution planning of pediatric resources. Further research is planned in this area. The practical implications of this study are the need for reliable data for research purposes and policy development for children. We conclude that the assessment of SA by focusing on the pediatric population using GIS was useful for visualizing areas short of pediatric healthcare services and that this analysis could become a helpful tool for monitoring SA at local level in Japan. Acknowledgments This study was financially supported by a Grant-in-Aid from The Japanese Ministry of Education, Culture, Sports, Science and Technology (Monbukagakusho). F. Cervigni would like to thank the Department of Public Health, Graduate School of Medicine, Chiba University for support in the conduct of this research.
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