Background: Synthesizing the evidence for the effectiveness of complex interventions requires an understanding of contextual factors that influence; why, when, for whom and in what circumstances interventions may or may not work. Various methodological developments are evolving to enable a greater understanding of the mechanisms that influence intervention effectiveness, such as inclusion of qualitative evidence and realist synthesis approaches. This study sought to explore the value of a qualitative assessment of the discussion section in the included RCTs in a review. Frequently this section allows the authors to describe why the results of the study were or were not as expected, yet it’s frequently overlooked in data extraction.

Objectives: To compare the insights from discussion sections of included RCT’s with the results of a synthesis of qualitative research studies.

Methods: We undertook a review of brief interventions to promote physical activity. To understand the barriers and facilitators of such interventions we conducted a synthesis of qualitative studies alongside a synthesis of RCTs. We also conducted a qualitative analysis of the discussion sections of the RCTs to see if they also identified barriers and facilitators and how these compared to the findings of the qualitative studies.

Results and Conclusion: The value of the discussion sections was they were reliable in terms of being directly relevant to the studies on which they were commenting. Qualitative studies may have been conducted indifferent cultural contexts and findings maybe inappropriately used to interpret findings of RCTs. There were some themes that occurred in both the discussion sections and in the analysis of qualitative studies. However, the perspectives of participants were rarely given voice in discussion sections of RCTs. Nonetheless, discussion section provide useful insights that can inform understanding of why certain results were obtained.