Are We There Yet? Distance to Pediatric Subspecialty Care in the US

1. Are We There Yet? Distance to Pediatric Subspecialty Care in the US Michelle L. Mayer, PhD, MPH Research Assistant Professor Department of Health Policy and Administration and Research Fellow CG Sheps Center for Health Services Research This work was funded by the Agency for Health Care Research and Quality grant 1-K02-HS013309-01A1

2. Access to Pediatric Subspecialty Care • There is currently debate about the adequacy of the pediatric subspecialty (PSS) workforce. • To date, there are few studies that adequately assess the availability of PSS care. • We do know that the majority of PSS are highly centralized in • academic medical centers • urban areas

3. Research Questions • How far do children travel for PSS care? • What county characteristics are associated with greater distances to PSS care? • What are the provider to population ratios across pediatric subspecialties? • How many children are needed to support pediatric subspecialists?

4. Data Sources • 2003 Diplomate File from the American Board of Pediatrics • Individual level file that contains gender, date of medical school graduation, and certification and expiration dates for all subspecialty certifications • 2003 data from the Bureau of Health Professions’ Area Resource File • County level composite file of data from multiple sources • 2003 population estimates from the Census Bureau

5. Research Question 1

6. Distance to Care • For each PSS, we calculated the straight-line distance between each county in the USA and the nearest provider. • We merged pediatric population data to distance data at the county level and estimated • population weighted average distance to care • % of the under 18 population living within selected distances of a provider

7. Table 1: Mean Population Weighted Distance to Care by PSS, US Counties

8. Table 2: Percent of Under 18 Population Living within Selected Distance by PSS, US Counties

9. Research Question 2

10. Identification of Areas Facing Geographic Access Barriers • Specialty-specific logit models • Dependent Variable: • Located 50 or more miles from a provider • Independent Variables of Interest: • Metropolitan Status (MSA) • Census Division • Models control for number of children under 18, per capita income, population density, and sociodemographic characteristics of the county

11. Counties “At-Risk” for Geographic Access Barriers • For all PSS, increased likelihood of being 50 or more miles from a provider associated with • Lower population density & smaller under-18 population • In West North Central region • In a non-metro area or MSA of less than 1 million people • Counties in the Pacific and Mountain regions were also at risk for a majority of specialties • The presence of a COTH facility was associated with a decreased risk for a handful of specialties

12. Research Question 3

13. Provider to Population Ratios • For each PSS, we calculated • Percent of MSA with one or more providers • Mean provider to population ratios across all MSA in the US • Coefficient of variation • MSA-level analysis used to allow for a larger market area

14. Table 3: Provider to under-18 Population Ratios by PSS, MSA

15. Research Question 4

16. Population Thresholds • For each PSS, we used ordered logit used to predict • population needed to support a single PSS, and • population increments needed to support additional providers. • MSA-level analysis used to allow for a larger market area • Dependent Variable • Number of providers in the MSA

17. Figure 1: Predicted Population Threshold Needed to Support a Single Provider by PSS, MSA 95% Confidence Interval

18. Figure 2: Population Increments Needed to Support Additional Providers in an MSA, Non-procedural Subspecialties

19. Figure 3: Population Increments Needed to Support Additional Providers in an MSA, Procedural & Intensivist Subspecialties

20. Figure 4: Population Increments Needed to Support Additional Providers in an MSA, Procedural & Intensivist Subspecialties

21. Discussion

22. Discussion • There is considerable variation in the population weighted distance to care across pediatric subspecialties. • For most PSS, more than three-quarters of the under-18 population lives within 50 miles of a provider county. • Risk for being more than 50 miles from a provider is associated with living in a • small metropolitan areas & rural areas • Mountain or WNC regions • county with fewer children

23. Discussion, cont. • Distance to care & population increments needed to attract a PSS vary considerable across PSS. • Disease prevalence • Type of specialty (procedural or cognitive) • When certification became available / size of the PSS • Overlap with IM subspecialties

24. Limitations • Some of the addresses may be home addresses, potentially biasing estimates. • Analysis assumes that a provider is involved in patient care. • In urban areas, straight-line distance underestimates the travel time needed to reach providers.

25. Future Research • Repeat distance analysis using zip code level data • More detailed studies needed to assess the adequacy of supply in areas that have providers: • Account for patient demand • Wait time for appointments • Estimates of provider-population ratios that adjust for provider availability for patient care • Qualitative studies of how children in areas distant from PSS receive care.