Improving accessibility to radiotherapy services in Cali, Colombia: cross-sectional equity analyses using open data and big data travel times from 2020
Authors: Cuervo Luis Gabriel , Villamizar Carmen Juliana , Cuervo Daniel , Zapata Pablo , Ospina Maria B. , Valencia Sara Marcela , Polo Alfredo , Suárez Ángela , Bula Maria O. , Miranda Jaime , Millán Gynna , Cuervo Diana Elizabeth , Owens Nancy J. , Piquero Felipe , Hatcher-Roberts Janet , Paredes Gabriel Dario , Navarro María Fernanda , Minotta Ingrid Liliana , Palta Carmen , Martínez-Herrera Eliana , Jaramillo Ciro 
Published: March 2024

In this study, we employed a methodology to evaluate and forecast the cumulative opportunities for residents to access radiotherapy services in Cali, Colombia, while accounting for traffic congestion from an equity perspective. Furthermore, we identified 1-2 optimal locations where new services would maximise accessibility. We utilised open data and publicly available big data.
Methodology:
Using a people-centred approach, we tested a web-based digital platform developed through design thinking. The platform integrates open data, including the location of radiotherapy services, the disaggregated sociodemographic microdata for the population and places of residence, and big data for travel times from Google Distance Matrix API. We used genetic algorithms to search heuristics to identify optimal locations for new services. We predicted accessibility cumulative opportunities (ACO) for traffic ranging from peak congestion to free-flow conditions at hourly assessments for 6–12 July 2020 and 23–29 November 2020. The interactive digital platform is openly available.
Primary and Secondary Outcomes:
We present descriptive statistics and population distribution heatmaps based on 20-minute Accessible Catchment Area (ACO) isochrones for car journeys. These isochrones connect the population-weighed centroid of the traffic analysis zone at the place of residence to the corresponding zone of the radiotherapy service with the shortest travel time under varying traffic conditions, ranging from free-flow to peak-traffic congestion levels. Additionally, we conducted a time-series bivariate analysis to assess geographical accessibility based on economic stratum. We identify 1–2 optimal locations where new services would maximise the 20-minute ACO during peak-traffic congestion.
Results:
Traffic congestion significantly diminished accessibility to radiotherapy services, particularly affecting vulnerable populations. For instance, urban 20-minute ACO by car dropped from 91% during free-flow traffic to 31% during peak traffic for the week of 6–12 July 2020. Specific ethnic groups, individuals with lower educational attainment, and residents in the outskirts of Cali experienced disproportionate effects, with accessibility decreasing to 11% during peak traffic compared to 81% during free-flow traffic for low-income households. We predict that strategically adding sufficient services in 1–2 locations in eastern Cali would notably enhance accessibility and reduce inequities. The recommended locations for new services remained consistent in both of our measurements.
These findings underscore the significance of prioritising equity and comprehensive care in healthcare accessibility. They also offer a practical approach to optimising service locations to mitigate disparities. Expanding this approach to encompass other transportation modes, services, and cities, or updating measurements, is feasible and affordable. The new approach and data are particularly relevant for planning authorities and urban development actors.