Using Medicaid claims to construct dental service market areas

Objective. To use Medicaid claims data to construct patient origin-based ma rket areas for dental services and compare constructed market areas with th ose based on the practice county. Data Sources. North Carolina Medicaid claims, eligibility, and provider fil es, the Cooperative Health Information Systems' dentist licensure files, an d the Log Into North Carolina data. Study Design. A visit-level file was created from the Medicaid claims data and aggregated by provider practice county and patient county of residence. Using the aggregated file and an algorithm based on the Elzinga-Hogarty ap proach, patient travel patterns were used to construct mutually exclusive p atient origin market areas. Data Analysis. Market area characteristics were compared across definitions using Pearson correlation coefficients. In addition, estimations of provid er participation were performed using market area characteristics as contro l variables. The beta coefficients associated with market area characterist ics were compared across market area definitions. Principal Findings. Medicaid claims data, when combined with provider licen sure files, can be used to construct market areas based on patient origin d ata. However, measures of market area characteristics are correlated highly between the two types of market areas studied. Furthermore, beta coefficie nts on market area variables in models of provider participation are simila r in sign, significance, and magnitude across market definitions. Conclusions. Compared with market areas constructed using patient origin da ta, county-based market areas adequately proxy for dental markets. Using th e county as the market area also avoids the time and computational costs as sociated with using a patient origin-based approach and facilitates the use of widely available data.