title: Emergency department crowding in Singapore: Insights from a systems thinking approach.
abstract: OBJECTIVE
  Emergency Department crowding is a serious and international health care problem that seems to be resistant to most well intended but often reductionist policy approaches. In this study, we examine Emergency Department crowding in Singapore from a systems thinking perspective using causal loop diagramming to visualize the systemic structure underlying this complex phenomenon. Furthermore, we evaluate the relative impact of three different policies in reducing Emergency Department crowding in Singapore: introduction of geriatric emergency medicine, expansion of emergency medicine training, and implementation of enhanced primary care.
  
  
  METHODS
  The construction of the qualitative causal loop diagram is based on consultations with Emergency Department experts, direct observation, and a thorough literature review. For the purpose of policy analysis, a novel approach, the path analysis, is applied.
  
  
  RESULTS
  The path analysis revealed that both the introduction of geriatric emergency medicine and the expansion of emergency medicine training may be associated with undesirable consequences contributing to Emergency Department crowding. In contrast, enhancing primary care was found to be germane in reducing Emergency Department crowding; in addition, it has apparently no negative side effects, considering the boundary of the model created.
  
  
  CONCLUSIONS
  Causal loop diagramming was a powerful tool for eliciting the systemic structure of Emergency Department crowding in Singapore. Additionally, the developed model was valuable in testing different policy options.
authors.affiliation: Faculty of Business and Economics, University of Basel, Basel, Switzerland.
authors.forename: Lukas K
authors.initials: LK
authors.lastname: Schoenenberger
authors.affiliation: Program in Health Services and Systems Research, Duke-NUS Graduate Medical School, Singapore.
authors.forename: Steffen
authors.initials: S
authors.lastname: Bayer
authors.affiliation: Program in Health Services and Systems Research, Duke-NUS Graduate Medical School, Singapore.
authors.forename: John P
authors.initials: JP
authors.lastname: Ansah
authors.affiliation: Program in Health Services and Systems Research, Duke-NUS Graduate Medical School, Singapore; Department of Medicine, Duke University Medical Center, Durham, NC, USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Matchar
authors.affiliation: Health Services Research and Biostatistics Unit, Division of Research, Singapore General Hospital, Singapore.
authors.forename: Rajagopal L
authors.initials: RL
authors.lastname: Mohanavalli
authors.affiliation: Health Services Research and Biostatistics Unit, Division of Research, Singapore General Hospital, Singapore.
authors.forename: Sean Sw
authors.initials: SS
authors.lastname: Lam
authors.affiliation: Program in Health Services and Systems Research, Duke-NUS Graduate Medical School, Singapore; Department of Emergency Medicine, Singapore General Hospital, Singapore.
authors.forename: Marcus Eh
authors.initials: ME
authors.lastname: Ong
keywords: Critical care/emergency medicine; Emergency Department crowding; causal loop diagramming; modelling; path analysis; policy analysis; systems thinking