Reaching consensus on the definition of modifiable determinants of health: a Delphi study.

Introduction: The term 'modifiable risk factor' and similar variations of the expression are common across health literature. Despite this, there is no universal definition for what would be modifiable when considering the factors that increase risk of ill health or enable good health and well-being. We conducted a Delphi study aiming to reach consensus among interdisciplinary experts on the definition and conceptualisation of what would be considered 'modifiable' as health determinants. Methods: The Delphi statements were based on initial criteria conceptualised by the research team and published in an opinion article. 103 experts from a range of interdisciplinary backgrounds were invited to participate in the Delphi. The statements were adjusted based on the results of the first round and circulated to participants in a second round. Results: 33 experts completed the first round. 4 out of 10 statements achieved consensus (≥70%). 30/33 (90%) of experts completed the second round, and a further one out of three statements achieved consensus. Combining results from both rounds, we have reached this definition: 'A modifiable health determinant must be potentially changeable through direct and/or indirect interventions at the individual or population levels, and it must be possible to quantify or describe such change in some way. Whether a health determinant is modifiable is context- and system-dependent (including the social, economic, political, commercial and environmental contexts); therefore, transparent consideration of a context-dependent definition is recommended in research design and reporting'. Conclusions: This study offers a consensus-based view on what can be considered 'modifiable'. Having a common understanding of the term facilitates interdisciplinary collaboration in health research and translation of findings to policy and practice.