Effect of Regional Hospital Market Competition on Use Patterns of Free Flap Breast Reconstruction. 
Market competition is believed to promote patient access and health care delivery.  The authors examined the relationship between market competition and use of surgical services for cancer, using free flap immediate breast reconstruction as a model scenario.  This retrospective cross-sectional analysis of the 2008 to 2011 Nationwide Inpatient Sample identified female patients undergoing immediate breast reconstruction.  The Herfindahl-Hirschman Index was used to describe hospital markets as competitive or consolidated.  The relationship between market competition and free flap immediate breast reconstruction use was explored using a hierarchical model before and after race stratification.  Seven thousand three hundred seventy-two (10.7 percent) of 68,966 patients underwent free flap immediate breast reconstruction.  A consolidated market was associated with 35 percent lower odds of free flap immediate breast reconstruction (95 percent CI, 0.43 to 0.97).  Undergoing an operation in a later year [OR, 1.40; 95 percent CI (per year), 1.21 to 1.63], nonwhite race (OR, 1.33; 95 percent CI, 1.10 to 1.60), private insurance (OR, 2.09; 95 percent CI, 1.59 to 2.76), and teaching hospital status (OR, 2.67; 95 percent CI, 1.73 to 4.13) were associated with higher rates of free flap reconstruction.  Market consolidation was associated with 48 percent lower odds of undergoing free flap immediate breast reconstruction in nonwhite patients only (95 percent CI, 0.29 to 0.92).  A hospital's willingness to provide surgical services may be subject to market pressures.  Market competition is associated with increased odds of free flap immediate breast reconstruction and higher use by racial minorities.