Methods to measure potential spatial access to delivery care in low- and middle-income countries: a case study in rural Ghana
Tóm tắt
Access to skilled attendance at childbirth is crucial to reduce maternal and newborn mortality. Several different measures of geographic access are used concurrently in public health research, with the assumption that sophisticated methods are generally better. Most of the evidence for this assumption comes from methodological comparisons in high-income countries. We compare different measures of travel impedance in a case study in Ghana’s Brong Ahafo region to determine if straight-line distance can be an adequate proxy for access to delivery care in certain low- and middle-income country (LMIC) settings. We created a geospatial database, mapping population location in both compounds and village centroids, service locations for all health facilities offering delivery care, land-cover and a detailed road network. Six different measures were used to calculate travel impedance to health facilities (straight-line distance, network distance, network travel time and raster travel time, the latter two both mechanized and non-mechanized). The measures were compared using Spearman rank correlation coefficients, absolute differences, and the percentage of the same facilities identified as closest. We used logistic regression with robust standard errors to model the association of the different measures with health facility use for delivery in 9,306 births. Non-mechanized measures were highly correlated with each other, and identified the same facilities as closest for approximately 80% of villages. Measures calculated from compounds identified the same closest facility as measures from village centroids for over 85% of births. For 90% of births, the aggregation error from using village centroids instead of compound locations was less than 35 minutes and less than 1.12 km. All non-mechanized measures showed an inverse association with facility use of similar magnitude, an approximately 67% reduction in odds of facility delivery per standard deviation increase in each measure (OR = 0.33). Different data models and population locations produced comparable results in our case study, thus demonstrating that straight-line distance can be reasonably used as a proxy for potential spatial access in certain LMIC settings. The cost of obtaining individually geocoded population location and sophisticated measures of travel impedance should be weighed against the gain in accuracy.
Tài liệu tham khảo
Bhutta ZA, Black RE: Global maternal, newborn, and child health--so near and yet so far. N Engl J Med. 2013, 369 (23): 2226-2235.
Gabrysch S, Campbell OM: Still too far to walk: literature review of the determinants of delivery service use. BMC Pregnancy Childbirth. 2009, 9: 34-
Gabrysch S, Cousens S, Cox J, Campbell OM: The influence of distance and level of care on delivery place in rural Zambia: a study of linked national data in a geographic information system. PLoS Med. 2011, 8 (1): e1000394-
Guagliardo MF: Spatial accessibility of primary care: concepts, methods and challenges. Int J Health Geogr. 2004, 3 (1): 3-
Khan AA: An integrated approach to measuring potential spatial access to health care services. Socioecon Plann Sci. 1992, 26 (4): 275-287.
Penchansky R, Thomas JW: The concept of access: definition and relationship to consumer satisfaction. Med Care. 1981, 19 (2): 127-140.
Wang F, Luo W: Assessing spatial and nonspatial factors for healthcare access: towards an integrated approach to defining health professional shortage areas. Health Place. 2005, 11 (2): 131-146.
Ray N, Ebener S: AccessMod 3.0: computing geographic coverage and accessibility to health care services using anisotropic movement of patients. Int J Health Geogr. 2008, 7: 63-
Delamater PL, Messina JP, Shortridge AM, Grady SC: Measuring geographic access to health care: raster and network-based methods. Int J Health Geogr. 2012, 11 (1): 15-
Neis P, Zielstra D, Zipf A: Comparison of volunteered geographic information data contributions and community development for selected world regions. Future Internet. 2013, 5 (2): 282-300.
Tanser FC, Le Sueur D: The application of geographical information systems to important public health problems in Africa. Int J Health Geogr. 2002, 1 (1): 4-
Frizzelle BG, Evenson KR, Rodriguez DA, Laraia BA: The importance of accurate road data for spatial applications in public health: customizing a road network. Int J Health Geogr. 2009, 8: 24-
Tanser F, Gijsbertsen B, Herbst K: Modelling and understanding primary health care accessibility and utilization in rural South Africa: an exploration using a geographical information system. Soc Sci Med. 2006, 63 (3): 691-705.
Okwaraji YB, Cousens S, Berhane Y, Mulholland K, Edmond K: Effect of geographical access to health facilities on child mortality in rural Ethiopia: a community based cross sectional study. PLoS One. 2012, 7 (3): e33564-
Noor AM, Amin AA, Gething PW, Atkinson PM, Hay SI, Snow RW: Modelling distances travelled to government health services in Kenya. Trop Med Int Health. 2006, 11 (2): 188-196.
Costa LS, Nassi CD, Pinheiro RS, Almeida RMVR: Accessibility of selected hospitals and medical procedures by means of aerial and transit network-based measures. Health Serv Manage Res. 2003, 16 (2): 136-140.
Cudnik MT, Yao J, Zive D, Newgard C, Murray AT: Surrogate markers of transport distance for out-of-hospital cardiac arrest patients. Prehosp Emerg Care. 2012, 16 (2): 266-272.
Lian M, Struthers J, Schootman M: Comparing GIS-based measures in access to mammography and their validity in predicting neighborhood risk of late-stage breast cancer. PLoS One. 2012, 7 (8): e43000-
Jones SG, Ashby AJ, Momin SR, Naidoo A: Spatial implications associated with using Euclidean distance measurements and geographic centroid imputation in health care research. Health Serv Res. 2010, 45 (1): 316-327.
Apparicio P, Abdelmajid M, Riva M, Shearmur R: Comparing alternative approaches to measuring the geographical accessibility of urban health services: distance types and aggregation-error issues. Int J Health Geogr. 2008, 7: 7-
Fone DL, Christie S, Lester N: Comparison of perceived and modelled geographical access to accident and emergency departments: a cross-sectional analysis from the Caerphilly Health and Social Needs Study. Int J Health Geogr. 2006, 5: 16-
Haynes R, Jones AP, Sauerzapf V, Zhao H: Validation of travel times to hospital estimated by GIS. Int J Health Geogr. 2006, 5: 40-
Fortney PD, Rost J, Warren J: Comparing alternative methods of measuring geographic access to health services. Health Serv Outcomes Res Methodol. 2000, 1 (2): 173-184.
European Space Agency: GlobCover. [http://due.esrin.esa.int/globcover/] Last Accessed: March 5, 2014 [] Last Accessed: March 5, 2014
Global Environment Monitoring Unit - Joint Research Centre of the European Commission: Travel time to major cities: A global map of Accessibility. [http://bioval.jrc.ec.europa.eu/products/gam/sources.htm] Last Accessed: March 10, 2014 [] Last Accessed: March 10, 2014
Lozano R, Wang H, Foreman KJ, Rajaratnam JK, Naghavi M, Marcus JR, Dwyer-Lindgren L, Lofgren KT, Phillips D, Atkinson C, Lopez AD, Murray CJ: Progress towards Millennium Development Goals 4 and 5 on maternal and child mortality: an updated systematic analysis. Lancet. 2011, 378 (9797): 1139-1165.
Edmond K, Hurt L, Fenty J, Amenga-Etego S, Zandoh C, Hurt C, Danso S, Tawiah C, Hill Z, Ten Asbroek AH, Owusu-Agyei S, Campbell O, Kirkwood BR: Effect of vitamin A supplementation in women of reproductive age on cause-specific early and late infant mortality in rural Ghana: ObaapaVitA double-blind, cluster-randomised, placebo-controlled trial. BMJ Open. 2012, 2 (1): e000658-
Kirkwood BR, Manu A, ten Asbroek AH, Soremekun S, Weobong B, Gyan T, Danso S, Amenga-Etego S, Tawiah-Agyemang C, Owusu-Agyei S, Hill Z: Effect of the Newhints home-visits intervention on neonatal mortality rate and care practices in Ghana: a cluster randomised controlled trial. Lancet. 2013, 381 (9884): 2184-2192.
Kirkwood BR, Manu A, Tawiah-Agyemang C, ten Asbroek G, Gyan T, Weobong B, Lewandowski RE, Soremekun S, Danso S, Pitt C: NEWHINTS cluster randomised trial to evaluate the impact on neonatal mortality in rural Ghana of routine home visits to provide a package of essential newborn care interventions in the third trimester of pregnancy and the first week of life: trial protocol. Trials. 2010, 11: 58-
Ghana Statistical Service: Ghana 2003 Core Welfare Indicators Questionnaire (CWIQ II) Survey Report: Statistical Abstract In. 2003, Ghana Statistical Service: Accra
Neteler M, Bowman MH, Landa M, Metz M: GRASS GIS: a multi-purpose open source GIS. Environ Model Softw. 2012, 31: 124-130.
Bailey PE, Keyes EB, Parker C, Abdullah M, Kebede H, Freedman L: Using a GIS to model interventions to strengthen the emergency referral system for maternal and newborn health in Ethiopia. Int J Gynaecol Obstetr. 2011, 115 (3): 300-309.
Gething PW, Johnson FA, Frempong-Ainguah F, Nyarko P, Baschieri A, Aboagye P, Falkingham J, Matthews Z, Atkinson PM: Geographical access to care at birth in Ghana: a barrier to safe motherhood. BMC Public Health. 2012, 12: 991-
World Health Organization (WHO): Monitoring Emergency Obstetric Care. A Handbook. 2009
Vesel L, Manu A, Lohela TJ, Gabrysch S, Okyere E, Ten Asbroek AH, Hill Z, Agyemang CT, Owusu-Agyei S, Kirkwood BR: Quality of newborn care: a health facility assessment in rural Ghana using survey, vignette and surveillance data. BMJ Open. 2013, 3 (5): e002326-
Nesbitt RC, Lohela TJ, Manu A, Vesel L, Okyere E, Edmond K, Owusu-Agyei S, Kirkwood BR, Gabrysch S: Quality along the continuum: a health facility assessment of intrapartum and postnatal care in Ghana. PLoS One. 2013, 8 (11): e81089-
Metz M, Mitasova H, Harmon RS: Efficient extraction of drainage networks from massive, radar-based elevation models with least cost path search. Hydrol Earth Syst Sc. 2011, 15 (2): 667-678.
Luo L, McLafferty S, Wang F: Analyzing spatial aggregation error in statistical models of late-stage cancer risk: a Monte Carlo simulation approach. Int J Health Geogr. 2010, 9: 51-
Apparicio P, Shearmur R, Brochu M, Dussault G: The measure of distance in a social science policy context: advantages and costs of using network distances in eight Canadian metropolitan areas. J Geogr Inf Decis Anal. 2003, 7 (2): 105-131.