When more is less: What explains the overuse of health care services in China? 
Overuse of health care services has become an increasingly severe problem in China.  However, as both academic interests and practical efforts have mainly focused on reducing underuse, our understanding of overuse is far from complete.  This study aims to analyze the status of overuse of health care services in China and explore both the supply- and demand-side factors associated with overuse.  We took common cold, a self-limiting viral infection which requires no injections or infusions, as a tracer condition.  Based on data from the fourth and fifth Health Service Survey of Shaanxi Province, we generated an observable indicator to measure overuse: whether or not a patient received infusion treatment for common cold during outpatient visits.  The statistics showed that 58.73% and 37.56% of patients had infusion treatment for common cold during outpatient visits in 2008 and 2013, respectively.  Based on this dependent variable, we employed Probit analysis to investigate factors influencing the overuse of health care services.  The multivariate regression results showed that on the demand side, overuse was positively associated with low health literacy, long duration of illness, large family size, and high economic status.  On the supply side, overuse was relatively high in hospitals at the county level and above as well as in cities with relatively low density of health care workforce.  Our results also provided some evidence for the effectiveness of health care reform policies like the essential medicines programme in reducing overuse.