Logic models help make sense of complexity in systematic reviews and health technology assessments

OBJECTIVE: To describe the development and application of logic model templates for systematic reviews and health technology assessments (HTA) of complex interventions STUDY DESIGN AND SETTING: This study demonstrates the development of a method to conceptualise complexity and make underlying assumptions transparent. Examples from systematic reviews with specific relevance to sub-Saharan Africa (SSA) and other low- and middle-income countries (LMICs) illustrate its usefulness. RESULTS: Two distinct templates are presented: the system-based logic model, describing the system in which the interaction between participants, intervention and context takes place; and the process-orientated logic model, which displays the processes and causal pathways that lead from the intervention to multiple outcomes. CONCLUSION: Logic models can help authors of systematic reviews and HTAs to explicitly address and make sense of complexity, adding value by achieving a better understanding of the interactions between the intervention, its implementation and its multiple outcomes among a given population and context. They thus have the potential to help build systematic review capacity -in SSA and other LMICs - at an individual level, by equipping authors with a tool that facilitates the review process; and at a system-level, by improving communication between producers and potential users of research evidence.