Using natural experiments to evaluate population health interventions: a framework for producers and users of evidence

Background:
There has been a substantial increase in the conduct of natural experimental evaluations in the last 10 years. This has been driven by advances in methodology, greater availability of large routinely collected datasets, and a rise in demand for evidence about the impacts of upstream population health interventions. It is important that researchers, practitioners, commissioners, and users of intervention research are aware of the recent developments. This new framework updates and extends existing Medical Research Council guidance for using natural experiments to evaluate population health interventions.

Methods:
The framework was developed with input from three international workshops and an online consultation with researchers, journal editors, funding representatives, and individuals with experience of using and commissioning natural experimental evaluations. The project team comprised researchers with expertise in natural experimental evaluations. The project had a funder-assigned oversight group and an advisory group of independent experts.

Results:
The framework defines key concepts and provides an overview of recent advances in designing and planning evaluations of natural experiments, including the relevance of a systems perspective, mixed methods and stakeholder involvement throughout the process. It provides an overview of the strengths, weaknesses, applicability and limitations of the range of methods now available, identifies issues of infrastructure and data governance, and provides good practice considerations.

LIMITATIONS:
The framework does not provide detailed information for the substantial volume of themes and material covered, rather an overview of key issues to help the conduct and use of natural experimental evaluations.

Conclusion:
This updated and extended framework provides an integrated guide to the use of natural experimental methods to evaluate population health interventions. The framework provides a range of tools to support its use and detailed, evidence-informed recommendations for researchers, funders, publishers, and users of evidence.

Study Registration:
This methodological project was not registered.

Funding:
This project was jointly funded by the Medical Research Council (MRC) and National Institute for Health and Care Research (NIHR), with project reference MC_PC_21009. The work is published in full in Public Health Research; Vol. 13, No. 3.