title: The impact of continuity of care on emergency room use in a health care system without referral management: an instrumental variable approach.
abstract: OBJECTIVE
  The purpose of the study was to determine whether continuity of care (COC) is beneficial in national health care systems without referral management by controlling for endogeneity of COC.
  
  
  METHODS
  We used National Health Insurance (Taiwan) claims data from 2008, encompassing approximately 23 million people, to determine whether COC is associated with reduced emergency room (ER) use by hypertension and diabetic patients in 2009. We used an instrumental variable approach to account for endogeneity associated with patients' COC levels.
  
  
  RESULTS
  After controlling for endogeneity, the marginal effect of COC on ER use probability when the COC score increased from 0 to 1 was 7.6% (P < .001) and 14.8% (P < .001) for hypertension and diabetic patients, respectively.
  
  
  CONCLUSIONS
  We determined that COC is more effective for reducing ER use than are models that assume that COC is exogenous. It has been argued that in many countries, health care systems without referral management encourage physician shopping and hinder physician-patient communication. However, there are benefits to disease-specific COC. Because current estimations have failed to take endogeneity biases into account, COC is more effective than is currently assumed.
authors: Department of Public Health, National Yang-Ming University, Taipei, Taiwan ROC. Electronic address: cypu@ym.edu.tw.
authors: Christy
authors: C
authors: Pu
authors: Department of Public Health, National Yang-Ming University, Taipei, Taiwan ROC.
authors: Yiing-Jenq
authors: YJ
authors: Chou
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003266:Continuity of Patient Care / Q000458:organization & administration*; D016208:Databases, Factual; D003924:Diabetes Mellitus, Type 2 / Q000628:therapy*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012017:Referral and Consultation; D013624:Taiwan
keywords: Continuity of care; Emergency room; Instrumental variable; Referral system