Conceptualising natural and quasi experiments in public health

de Vocht, F., Katikireddi, S. V. , McQuire, C., Tilling, K., Hickman, M. and Craig, P. (2021) Conceptualising natural and quasi experiments in public health. BMC Medical Research Methodology, 21(1), 32. (doi: 10.1186/s12874-021-01224-x) (PMID:33573595)

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Background: Natural or quasi experiments are appealing for public health research because they enable the evaluation of events or interventions that are difficult or impossible to manipulate experimentally, such as many policy and health system reforms. However, there remains ambiguity in the literature about their definition and how they differ from randomized controlled experiments and from other observational designs. We conceptualise natural experiments in the context of public health evaluations and align the study design to the Target Trial Framework. Methods: A literature search was conducted, and key methodological papers were used to develop this work. Peer-reviewed papers were supplemented by grey literature. Results: Natural experiment studies (NES) combine features of experiments and non-experiments. They differ from planned experiments, such as randomized controlled trials, in that exposure allocation is not controlled by researchers. They differ from other observational designs in that they evaluate the impact of events or process that leads to differences in exposure. As a result they are, in theory, less susceptible to bias than other observational study designs. Importantly, causal inference relies heavily on the assumption that exposure allocation can be considered ‘as-if randomized’. The target trial framework provides a systematic basis for evaluating this assumption and the other design elements that underpin the causal claims that can be made from NES. Conclusions: NES should be considered a type of study design rather than a set of tools for analyses of non-randomized interventions. Alignment of NES to the Target Trial framework will clarify the strength of evidence underpinning claims about the effectiveness of public health interventions.

Item Type:Articles
Additional Information:This study is funded by the National Institute for Health Research (NIHR) School for Public Health Research (Grant Reference Number PD-SPH-2015). SVK and PC acknowledge funding from the Medical Research Council (MC_UU_12017/13) and Scottish Government Chief Scientist Office (SPHSU13). SVK acknowledges funding from a NRS Senior Clinical Fellowship (SCAF/15/02). KT works in the MRC Integrative Epidemiology Unit, which is supported by the Medical Research Council (MRC) and the University of Bristol [MC_UU_00011/3].
Glasgow Author(s) Enlighten ID:Craig, Professor Peter and Katikireddi, Professor Vittal
Authors: de Vocht, F., Katikireddi, S. V., McQuire, C., Tilling, K., Hickman, M., and Craig, P.
College/School:College of Medical Veterinary and Life Sciences > Institute of Health and Wellbeing > MRC/CSO SPHSU
Journal Name:BMC Medical Research Methodology
Publisher:BioMed Central
ISSN (Online):1471-2288
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in BMC Medical Research Methodology 21(1):32
Publisher Policy:Reproduced under a Creative Commons License
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
Medical Research Council (MRC)MC_UU_12017/13
Chief Scientist Office (CSO)SPHSU13
Medical Research Council (MRC)MC_UU_00022/2
172690Understanding the impacts of welfare policy on health: A novel data linkage studySrinivasa KatikireddiChief Scientist Office (CSO)SCAF/15/02HW - Public Health