Beyond black and white: A framework for identifying grey literature in palliative care research

Research evidence is fundamental to informing clinical decision-making and advancing palliative care practice. Although academic, peer-reviewed journals underpin evidence-based healthcare, they represent only part of the knowledge landscape. Incorporating grey literature from sources outside traditional academic publishing can: provide context, balance and diverse perspectives; address knowledge gaps; and mitigate publication bias. However, its decentralised and dispersed nature can pose challenges for researchers unfamiliar with its scope and diversity.

To present a flexible framework comprising 12 elements to support researchers in systematically identifying and locating grey literature relevant to palliative care across a broad range of sources. The framework accommodates variation in research focus, available resources, and context. Practical guidance is also provided for reporting grey literature searches with the transparency required in systematic reviews.

The framework was developed through expert consensus, informed by the authors' collective experience in systematic review methodology, grey literature searching, and information retrieval. It has been iteratively refined through teaching and real-world review projects. Each included source was assessed for its depth and breadth of palliative care content.

The 12-element framework supports palliative care researchers in planning and executing searches across a wide range of fit-for-purpose sources. Practical examples are provided alongside a classification of grey literature source types.

This framework offers structured yet adaptable guidance to support more consistent grey literature engagement. Persistent challenges include defining search boundaries, managing duplication, record-keeping, and assessing quality. Future research should explore the framework's utility across diverse review types and palliative care research priorities.