Evaluation of complex interventions (CI) is challenging for health researchers and requires innovative approaches. The objective of this work is to present the main methods used to evaluate CI. A systematic review of the scientific literature was conducted to identify methods used for the evaluation of CI. We searched MEDLINE via PubMed databases for articles including an evaluation or a pilot study of a complex intervention, published in a ten-year period. Key-words of this research were (“complex intervention*” AND “evaluation”). Among 445 identified articles, 100 research results or protocols were included. Among them, 5 presented 2 different types of design in the same publication, thus our work included 105 designs. Individual randomized controlled trials (IRCT) represented 21.9% (n = 23) of evaluation designs, randomized clinical trials adaptations 44.8% (n = 47), quasi -experimental designs and cohort study 19.0% (n = 20), realist evaluation 6.7% (n = 7) and other cases studies and other approaches 8.6% (n = 9). A process/mechanisms analysis was included in 80% (n = 84) of these designs. A range of methods can be used successively or combined at various steps of the evaluation approach. A framework is proposed to situate each of the designs with respect to evaluation questions. The growing interest of researchers in alternative methods and the development of their use must be accompanied by conceptual and methodological research in order to more clearly define their principles of use.

Health education interventions are generally complex. Their outcomes result from both the intervention itself and the context for which they are developed. Thus, when an intervention carried out in one context is reproduced in another, its transferability can be questionable. We performed a literature review to analyze the concept of transferability in the health education field.

Background Public health interventions are increasingly being recognised as complex and context dependent. Related to this is the need for a systemic and dynamic conception of interventions that raises the question of delineating the scope and contours of interventions in complex systems. This means identifying which elements belong to the intervention (and therefore participate in its effects and can be transferred), which ones belong to the context and interact with the former to influence results (and therefore must be taken into account when transferring the intervention) and which contextual elements are irrelevant to the intervention. Discussion This paper, from which derives criteria based on a network framework, operationalises how the context and intervention systems interact and identify what needs to be replicated as interventions are implemented in different contexts. Representing interventions as networks (composed of human and non-human entities), we introduce the idea that the density of interconnections among the various entities provides a criterion for distinguishing core intervention from intervention context without disconnecting the two systems. This differentiates endogenous and exogenous intervention contexts and the mediators that connect them, which form the fuzzy and constantly changing intervention/context interface. Conclusion We propose that a network framework representing intervention/context systems constitutes a promising approach for deriving empirical criteria to delineate the scope and contour of what is replicable in an intervention. This approach should allow better identification and description of the entities that have to be transferred to ensure the potential effectiveness of an intervention in a specific context.

Objective: Health behaviour change interventions (HBCIs), used in health education, health promotion, patient education and psychotherapy areas, are considered complex interventions. The objective of this article is to discuss the value and limitations of using randomised clinical trials (RCTs) to asses HBCIs. Methods: A scoping review of the literature was conducted to identify the main challenges of using RCTs for evaluating HBCIs. The issues were illustrated by case studies selected from research conducted by our multidisciplinary team. Results: In complex interventions, effects are produced not only by the intervention, but are strongly linked to context. Issues relating to transferability of results are therefore critical, and require adjustments to the RCT model. Sampling bias, biases related to the experimental conditions and biases due to the absence of double-blindness were examined and illustrated by case studies. Conclusion: The results underline the importance of a multidisciplinary approach. They call for adapted or alternative evaluation models that overcome the limitations of RCTs.

Health promotion interventions are often complex and not easily transferable from one setting to another. The objective of this article is to present the development of a tool to analyze the transferability of these interventions and to support their development and adaptation to new settings.