Dissemination bias in qualitative research: conceptual considerations.

When the findings of relevant studies are not disseminated, and are therefore not accessible, data within evidence syntheses may be considered inadequate. In addition, if non-dissemination is systematic rather than random - that is, disseminated studies and findings differ systematically from non-disseminated studies and findings - this will cause bias. Such bias could occur due to several mechanisms, and is referred to by the term dissemination bias. The presence of dissemination bias could impact on our confidence in findings from qualitative evidence syntheses.

OBJECTIVE: We explore and discuss the issue of dissemination bias in qualitative research.

RESULTS: Based on what is known about dissemination bias in quantitative research, mechanisms causing time lag, language, grey literature and truncation bias are being transferred to qualitative research where they likely also contribute to dissemination bias. These conceptual considerations have informed the proposal of a research agenda.

CONCLUSION: Dissemination bias in qualitative research warrants greater exploration, including the extent of non-dissemination and related dissemination bias and how to assess dissemination bias in the context of qualitative evidence syntheses. We also need to further consider the mechanisms through which dissemination bias in qualitative research could occur in order to explore feasible approaches for reducing it.