The International Classification of Health Interventions: an 'epistemic hub' for use in public health.

The current lack of a common basis for collecting data on population-level prevention and health promotion interventions causes public health to be relatively invisible within broader health systems, making it vulnerable to funding cuts when there is pressure to reduce spending. Further, the inconsistent use of terms for describing interventions hinders knowledge translation and building an evidence base for public health practice and policy. The International Classification of Health Interventions (ICHI), being developed by the World Health Organization, is a standard statistical classification for interventions across the full scope of health systems. ICHI has potential to meet the need for a common language and structure for describing and capturing information about prevention and health promotion interventions. We report on a developmental appraisal conducted to examine the strengths and limitations of ICHI for coding interventions delivered for public health purposes. Our findings highlight classification challenges in relation to: consistently identifying separate components within multi-component interventions; operationalizing the ICHI concept of intervention target when there are intermediary targets as well as an ultimate target; coding an intervention component that involves more than one ICHI target or action; and standardising what is being counted. We propose that, alongside its purpose as a statistical classification, ICHI can play a valuable role as an 'epistemic hub', to be used flexibly by public health actors to meet a range of information needs, and as a basis for improved communication and exchange.