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Complexity in health care

“Complexity” is a term understood in different ways. It has a long history in fields like systems theory, artificial intelligence and mathematics. It has been taken up much more slowly in medicine, public health and health systems research. In these domains, there is still some important conceptual confusion around the definition of ‘complexity’.

Only a few publications bridge complexity theory and organisation of health care in a useful manner. Complexity was taken up more rapidly by the evaluation community and many interesting insights originate from that field. Also in the domain of management, complexity became a prominent topic in the 1990s.


Example of a model linking management practices to organisational performance:


In health systems, complexity can be applied to (1) organisations, (2) problems and (3) policies, management interventions and programmes.

Health care organisations are complicated systems

  • They are staffed by cadres having their specific competences, cultures and shared mental models.
  • They are made up by different units and levels.
  • Staff and units relate and interact to each other through formal and informal channels.
  • Each unit is dealing with different tasks and specialised functions, but all units need to be working towards the shared goal of providing care to patients.


Health care organisations are also complex systems

It is the actors’ “agency” at work in social relationships and feedback mechanisms that make health care organisations complex.

  • Interactions lead to new unpredictable actions of the actors (emergence).
  • But these emergent behaviours are somehow restricted by the history (path dependency) and the “structure” (formal and informal rules) of the organisation.
Sturmberg and Martin (2009) present a concise overview of how health care has all the characteristics of complex systems, with both clinical and health care organisation examples.



Problems or situations can be complex

Problems or situations are complex if they are determined by multiple, interacting factors. The people involved, their interactions and the specific context they live and work in shape webs of connections and relations. The interactions may involve positive or negative feedback loops. Understanding such complex situations requires the disentangling of intervention, actors, mechanisms of change, outcome and context.


Some policies, management interventions and programmes are complex

Health policies, management interventions and programmes are complex if  

  • they consist of various parts that interact with each other in non-linear, unpredictable ways
  • the underlying mechanism of change has a complex nature or is unknown
Hill (2010) applied complex systems thinking to global policy.

Recommended reading

  • Cilliers, P. (1998) Complexity and postmodernism. Understanding complex systems, London and New York, Routledge.
  • Fulop, N., Allen, P., Clarke, A. & Black, N. (2001) Issues in studying the organisation and delivery of health services. IN Fulop, N., Allen, P., Clarke, A. & Black, N. (Eds.) Studying the Organisation and Delivery of Health Services: Research Methods. London, Routledge.
  • Glouberman, S. & Zimmerman, B. (2002) Complicated and complex systems: what would successful reform of Medicare look like? , Commission on the Future of Health Care in Canada.
  • Hill, P. S. (2010) Understanding global health governance as a complex adaptive system. Glob Public Health, 1-13.
  • Stacey, R., Griffin, D. & Shaw, P. (2000) Complexity and management. Fad or radical challenge to systems thinking?, London, Routledge.
  • Stame, N. (2004) Theory-based evaluation and types of complexity. Evaluation, 10, 58-76.
  • Sturmberg, J. & Martin, C. (2009) Complexity and health - yesterday's traditions, tomorrow's future. Journal of Evaluation in Clinical Practice, 15, 543-48.


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    TDI workshop

    On 22 and 23 November 2010, the Unit of Health Care Management, Department of Public Health (ITM), organised an international expert meeting on theory-driven evaluation.

    About 15 researchers presented research and evaluations and discussed the methodological challenges of realist evaluation, theory-driven evaluation and realist synthesis in health systems research.

    In total 30 researchers, policymakers and programme managers attended the workshop.

    About this website

    This theory-driven inquiry website is developed by the Health Care Management Unit of the Department of Public Health, Institute of Tropical Medicine, Antwerp and the Development Policy & Practice Unit of the Royal Tropical Institute, Amsterdam. We collaborate on the development and implementation of theory-driven inquiry in health systems research, and aim at stimulating a better understanding of the advantages of this approach among both researchers and policymakers. To this end, we are engaged in a number of research and evaluation studies that use TD inquiry principles.

    Institute of Tropical Medicine

    Unit of Health Care Management

    TD inquiry project evaluations
    Défi Jeunes

    TD inquiry research projects
    PhD Bruno Marchal
    PhD Pierre Blaise

    The cluster Research methodology for complexity in healthcare


    Bruno Marchal - personal page
    Guy Kegels - personal page
    Tom Hoerée
    Josefien Van Olmen - personal page
    Sara Van Belle




    Royal Tropical Institute

    Department of Development, Policy and Practice

    TD inquiry project evaluations

    Realist evaluation of ASHA program in a district (India)

    TD inquiry research projects

    Realist inquiry in capacity building
    PhD Marjolein Dieleman

    Research and evaluation methodology

    Marjolein Dieleman
    Barend Gerretsen
    Sumit Kane
    Prisca Zwanikken