ABSTRACT
Healthcare interventions have evolved in response to the complex problems facing health systems around the world. A recent survey of randomized controlled trials, supported by the main noncommercial funders of research in the United Kingdom, reports a diverse set of healthcare interventions evaluated in trials funded by the NHS between 1980 and 2002. In addition
CONTENTS
14.1 Introduction ................................................................................................ 185 14.2 What Is a Complex Intervention? ............................................................ 186 14.3 Sources of Complexity in a Systematic Review
of Complex Interventions ......................................................................... 187 14.3.1 Differential Effects across Populations and the Number
of Groups or Organizational Levels Targeted by the Intervention ........................................................................ 188
14.3.2 De nition and Characteristics of the Intervention ................... 188 14.3.3 Outcomes ........................................................................................ 190 14.3.4 Methodological Issues ................................................................... 191
14.3.4.1 Searching for Studies ...................................................... 191 14.3.4.2 Synthesis of Data ............................................................. 191
14.4 Implementation and External Validity ................................................... 192 14.5 Conclusion .................................................................................................. 194 Acknowledgment ................................................................................................ 194 References ............................................................................................................. 195
to trials of pharmacological and surgical interventions, the interventions evaluated include education and training, service delivery, psychological therapy, and complex care interventions [1]. Other examples of healthcare interventions that might be considered more complex are those acting at the level of the health system. These include interventions directed at health systems governance arrangements, such as the regulation of pharmaceutical sales; interventions directed at health systems nancial arrangements, such as mechanisms of nancing health care to reduce inequities; interventions directed at health systems delivery arrangements, such as multidisciplinary packages of care to manage chronic diseases; and interventions to promote change in professional practice or care delivery, such as guideline implementation strategies [2].
