A national evaluation of geographic accessibility and provider availability of obesity medicine diplomates in the United States between 2011 and 2019

Abstract

Background/objectives: Obesity is a pressing health concern within the United States (US). Obesity medicine "diplomates" receive specialized training, yet it is unclear if their accessibility and availability adequately serves the need. The purpose of this research was to understand how accessibility has evolved over time and assess the practicality of serving an estimated patient population with the current distribution and quantity of diplomates.

Methods: Population-weighted Census tracts in US counties were mapped to the nearest facility on a road network with at least one diplomate who specialized in adult (including geriatric) care between 2011 and 2019. The median travel time for all Census tracts within a county represented the primary geographic access measure. Availability was assessed by estimating the number of diplomates per 100 000 patients with obesity and the number of facilities able to serve assigned patients under three clinical guidelines.

Results: Of the 3371 diplomates certified since 2019, 3036 were included. The median travel time (weighted for county population) fell from 28.5 min [IQR: 13.7, 68.1] in 2011 to 9.95 min [IQR: 7.49, 18.1] in 2019. There were distinct intra- and inter-year travel time variations by race, ethnicity, education, median household income, rurality, and Census region (all P < 0.001). The median number of diplomates per 100 000 with obesity grew from 1 [IQR: 0.39, 1.59] in 2011 to 5 [IQR: 2.74, 11.4] in 2019. In 2019, an estimated 1.7% of facilities could meet the recommended number of visits for all mapped patients with obesity, up from 0% in 2011.

Conclusions: Diplomate geographic access and availability have improved over time, yet there is still not a high enough supply to serve the potential patient demand. Future studies should quantify patient-level associations between travel time and health outcomes, including whether the number of available diplomates impacts utilization.

Figure 1.

Longitudinal Changes in County-Level Travel Time to Obesity Medicine Diplomates. Travel time defined as the median travel time of all population weighted Census blocks within a county to the nearest facility on a road network with at least one obesity medicine diplomate.

Figure 2.

Percent of Facilities with Capacity to Serve the Mapped Patient Population. Darker shades and hatches for the National Heart, Lung and Blood Institute (NHLBI), Centers for Medicare and Medicaid Services (CMS), and Wadden et al. studies denote the minimum number of facilities assuming all patients received 1-hour visits, while lighter shades for those recommendations denote the maximum number of facilities assuming all patients received 30-minute visits.