Neighborhood social determinants of health and postoperative weight loss

New publication – Pratt, K.J., Hanks, A.S., Miller, H.J., Outrich, M., Breslin, L., Blalock, J., Noria, S., Brethauer, S., Needleman, B. and Focht, B. (2022) “The BARI-hoods Project: Neighborhood social determinants of health and postoperative weight loss using integrated EHR, Census, and county data,” Surgery for Obesity and Related Diseases, online first.

(I may be the first geographer to co-author a paper in Surgery for Obesity and Related Diseases, but I am willing to be corrected.)

HIGHLIGHTS

  • While living in close proximity to foods stores does not ensure utilization, in this study, patients who lived within a 10-minute walk to food stores had better weight loss two years after bariatric surgery.
  • Black patients with access to more food stores within a 10-minute walk and White patients with more access within a 5-minute walk had greater %TWL (percent total weight loss)  over 24 months.
  • Living in areas with lower poverty levels did not negatively affect weight loss for Black patients.
  • There were no significant associations for weight loss based on unemployment rate or proximity to fitness/recreational facilities and percent open area.

ABSTRACT
Background.  While social determinants of health (SDoH) have gained attention for their role in weight loss following bariatric surgery; electronic health record (EHR) data provides limited information beyond demographics associated with disparities in weight loss.

Objective. To integrate EHR, Census, and county data to explore disparities in SDoH and weight loss among patients in the largest populous county of Ohio.

Setting. 772 patients (82.1% female; 37.0% Black) who had primary bariatric surgery (48.7% gastric bypass) from 2015-2019 at The Ohio State University.

Methods. EHR variables included race, insurance, procedure, and %TWL at 2/3, 6, 12, and 24 months. Census variables included poverty and unemployment rates. County variables included food stores, fitness/recreational facilities, and open area within a 5- and 10-minute walk from home. Two mixed multilevel models were conducted with %TWL over 24 months, with visits as the between subjects factor; race, Census, county, insurance, and procedure variables were covariates. Two additional sets of models determined within group differences for Black and White patients.

Results. Access to more food stores within a 10-minute walk was associated with greater %TWL over 24 months (p=0.029). Black patients with access to more food stores within a 10-minute (p=0.017) and White patients with more access within a 5-minute walk (p=0.015) had greater %TWL over 24 months. Black patients who lived in areas with higher poverty rates (p=0.036) experienced greater %TWL over 24 months. No significant differences were found for unemployment rate or proximity to fitness/recreational facilities and open area.

Conclusion. Close proximity to food stores is associated with better weight loss two years after bariatric surgery. Lower poverty levels did not negatively affect Black patient weight loss.

Measuring the impacts of dockless micro-mobility services on public transit accessibility

New paper:  Liu, L. and Miller, H.J. (2022) “Measuring the impacts of dockless micro-mobility services on public transit accessibility,” Computers, Environment and Urban Systems, 98, 101885.

We develop new measures of the accessibility increments to public transit afforded by dockless micromobility. We apply this to public transit and Lime scooter data for Columbus.  We find that dockless micro-mobility services such as scooters can improve public transit accessibility, but the benefits are very uneven and face substantial challenges including capacity and cost.

Abstract: Dockless micromobility services have potential as a fast and flexible solution to short-distance trips and public transit’s first-mile/last-mile (FM/LM) access problem; however, these services also have limitations, including uneven spatial distribution, low capacity, and user out of pocket expense. This can impact on the ability of micromobility to enhance public transit accessibility. We introduce accessibility increment measures – the amount by which public transit accessibility improves due to micromobility services. We apply these measures to hypothetical trips using public transit and micromobility data from Columbus, Ohio, USA. We find dockless scooters can increase accessibility by multimodal public transit trips, with increments in the first mile significantly outweighing last mile accessibility increments. Accessibility increments are highly concentrated in the city center due to the distributions of scooters and bus stops. We also find that scooters’ accessibility increment contribution is highly unequal: a small number of scooters contribute most of the accessibility increments. Monetary cost simulations show that the first-mile accessibility increment will rapidly decrease and last-mile increment slightly increase with lower willingness to pay. Capacity simulations show a group of users’ accessibility increment will rapidly decrease as the group size increases, but this depends on whether they are competing or collaborating for scooters. Our results show that despite showing promising potentials, vendors and policymakers still need to address these issues to make collaboration between public transit and dockless micromobility sustainable and equitable. The paper provides measures and evidence for future transit and micromobility planning for scooter vendors and transit authorities.

 

Realizable accessibility: evaluating the reliability of public transit accessibility using high‑resolution real‑time data

New paper!  Liu, L., Porr, A. and Miller, H.J. (2022) “Realizable accessibility: Evaluating the reliability of public transit accessibility using high-resolution real-time data,” Journal of Geographical Systems, online first.

Take home message:

We develop a refined time geographic measure of accessibility via public transit using real-time vehicle location data. We also show how to use this measure with schedule data to analyze the reliability of public transit accessibility at the urban scale. To be published in a special issue on “Time Geography in the Age of Mobility Analytics” in the Journal of Geographical Systems.

Abstract:

The widespread availability of high spatial and temporal resolution public transit data is improving the measurement and analysis of public transit-based accessibility to crucial community resources such as jobs and health care. A common approach is leveraging transit route and schedule data published by transit agencies. However, this often results in accessibility overestimations due to endemic delays due to traffic and incidents in bus systems. Retrospective real-time accessibility measures calculated using real-time bus location data attempt to reduce overestimation by capturing the actual performance of the transit system. These measures also overestimate accessibility since they assume that riders had perfect information on systems operations as they occurred. In this paper, we introduce realizable real-time accessibility based on space–time prisms as a more conservative and realistic measure. We, moreover, define accessibility unreliability to measure overestimation of schedulebased and retrospective accessibility measures. Using high-resolution General Transit Feed Specification real-time data, we conduct a case study in the Central Ohio Transit Authority bus system in Columbus, Ohio, USA. Our results prove that realizable accessibility is the most conservative of the three accessibility measures. We also explore the spatial and temporal patterns in the unreliability of both traditional measures. These patterns are consistent with prior findings of the spatial and temporal patterns of bus delays and risk of missing transfers. Realizable accessibility is a more practical, conservative, and robust measure to guide transit planning.