Assessing the complexity of interventions within systematic reviews: development, content and use of a new tool (iCAT_SR).
Simon Lewin, Maggie Hendry, Jackie Chandler, Andrew D Oxman, Susan Michie, Sasha Shepperd, Barnaby C Reeves, Peter Tugwell, Karin Hannes, Eva A Rehfuess, Vivien Welch, Joanne E Mckenzie, Belinda Burford, Jennifer Petkovic, Laurie M Anderson, Janet Harris, Jane Noyes
Author Information
Simon Lewin: Norwegian Institute of Public Health, Oslo, Norway. simon.lewin@fhi.no. ORCID
Maggie Hendry: North Wales Centre for Primary Care Research, Bangor University, Bangor, UK.
Jackie Chandler: Cochrane, Cochrane Central Executive, London, UK.
Andrew D Oxman: Norwegian Institute of Public Health, Oslo, Norway.
Susan Michie: Centre for Behaviour Change, University College London, London, UK.
Sasha Shepperd: Nuffield Department of Population Health, University of Oxford, Oxford, UK.
Barnaby C Reeves: Clinical Trials and Evaluation Unit, School of Clinical Sciences, University of Bristol, Bristol, UK.
Peter Tugwell: Institute of Population Health, University of Ottawa, Ottawa, Canada.
Karin Hannes: Social Research Methodology Group, Centre for Sociological Research, Faculty of Social Sciences, KU Leuven, Leuven, Belgium.
Eva A Rehfuess: Institute for Medical Informatics, Biometry and Epidemiology, University of Munich, Munich, Germany.
Vivien Welch: Bruyère Research Institute, Bruyère Continuing Care, Ottawa, Ontario, Canada.
Joanne E Mckenzie: School of Public Health and Preventive Medicine, The Alfred Centre, Monash University, Melbourne, Victoria, Australia.
Belinda Burford: Cochrane Public Health Group and Jack Brockhoff Child Health and Wellbeing Program, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.
Jennifer Petkovic: Campbell and Cochrane Equity Methods Group, Centre for Global Health, Institute of Population Health, University of Ottawa, Ottawa, Canada.
Laurie M Anderson: Department of Epidemiology, School of Public Health, University of Washington, Seattle, USA.
Janet Harris: School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, UK.
Jane Noyes: School of Social Sciences, Bangor University, Bangor, UK.
BACKGROUND: Health interventions fall along a spectrum from simple to more complex. There is wide interest in methods for reviewing 'complex interventions', but few transparent approaches for assessing intervention complexity in systematic reviews. Such assessments may assist review authors in, for example, systematically describing interventions and developing logic models. This paper describes the development and application of the intervention Complexity Assessment Tool for Systematic Reviews (iCAT_SR), a new tool to assess and categorise levels of intervention complexity in systematic reviews. METHODS: We developed the iCAT_SR by adapting and extending an existing complexity assessment tool for randomized trials. We undertook this adaptation using a consensus approach in which possible complexity dimensions were circulated for feedback to a panel of methodologists with expertise in complex interventions and systematic reviews. Based on these inputs, we developed a draft version of the tool. We then invited a second round of feedback from the panel and a wider group of systematic reviewers. This informed further refinement of the tool. RESULTS: The tool comprises ten dimensions: (1) the number of active components in the intervention; (2) the number of behaviours of recipients to which the intervention is directed; (3) the range and number of organizational levels targeted by the intervention; (4) the degree of tailoring intended or flexibility permitted across sites or individuals in applying or implementing the intervention; (5) the level of skill required by those delivering the intervention; (6) the level of skill required by those receiving the intervention; (7) the degree of interaction between intervention components; (8) the degree to which the effects of the intervention are context dependent; (9) the degree to which the effects of the interventions are changed by recipient or provider factors; (10) and the nature of the causal pathway between intervention and outcome. Dimensions 1-6 are considered 'core' dimensions. Dimensions 7-10 are optional and may not be useful for all interventions. CONCLUSIONS: The iCAT_SR tool facilitates more in-depth, systematic assessment of the complexity of interventions in systematic reviews and can assist in undertaking reviews and interpreting review findings. Further testing of the tool is now needed.
