Influence of changes in supply on the distribution of pediatric subspecialty care.

OBJECTIVES: To examine whether recently certified pediatric subspecialists enter markets that previously lacked subspecialists and to determine whether changes in overall supply are associated with changes in geographic availability of care.
DESIGN: Multiple cross-sectional analyses.
SETTING: United States. PARTICIPANTS: Physician data for 2003 and 2006 from the American Board of Pediatrics. Main Exposure New entrants, defined as subspecialists who first obtained certification after 2003. MAIN OUTCOME MEASURES: We examined the following: (1) whether new entrants were more likely to practice in locations lacking certified subspecialists; (2) changes in the percentage of hospital referral regions (HRRs) with at least 1 subspecialist; and (3) changes in the number of subspecialists per HRR.
RESULTS: Ten pediatric subspecialties experienced increases in supply and 5 experienced decreases. For 8 of the 15 pediatric subspecialties studied, new entrants were more likely than previously certified physicians to locate in an HRR that lacked a subspecialist in 2003. The percentage of HRRs with a subspecialist increased significantly for 3 of the 10 pediatric subspecialties with increases in supply. Among HRRs with a subspecialist in 2003, the average number of subspecialists per HRR increased between 2003 and 2006 for 6 of the 10 pediatric subspecialties with total supply increases and decreased for 4 of the 5 subspecialties with decreases in supply.
CONCLUSIONS: Increases in the number of pediatric subspecialists generally did not lead to improvements in distribution and may actually reinforce the existing distribution for certain pediatric subspecialties. However, because newly certified subspecialists are more likely to enter an HRR that previously lacked a subspecialist, long-term increases in supply may lead to improvements in distribution.