Selective referral or learning by doing? An analysis of hospital volume-outcome relationship of vascular procedures

This paper analyzes the effects of hospital volume on outcomes of patients undergoing percutaneous transluminal angioplasty (PTA) with stent implant in Slovakia between 2014 and 2019. The volume-outcome relationship is estimated jointly using a discrete factor approach, where choice of hospital is correlated with durations until readmission or death, accounting for observed and unobserved characteristics. The results reveal the importance of controlling for between-hospital differences and selectivity in patient referral. Estimates without hospital fixed effects overstate the positive effect of volume on outcomes, but the results remain statistically significant. Once selectivity is accounted for in the joint correlated model, the positive volume-outcome relationship is not different from zero. Overall, the main driver of the volume-outcome relationship for PTA procedures appears to be related to selective referral and differences in quality of health care providers.