Box 1 Recommendations on incorporating unpublished health system data with systematic reviews

1. Explicitly state the rationale for using unpublished health system data. The rationale could be to improve the strength and/or the applicability of evidence, and/or to inform its implementation.

2. Include details on how the data source was chosen, the relevance of the data source, and the type of data source (e.g., single vs. multisystem, electronic health record vs. clinical registry).

3. Characterize the limitations of any included data using formal critical appraisal criteria, as well as working with health system’s staff/researchers to understand data and information quality limitations.

4. Specify how the findings from unpublished data support, refute, and/or otherwise add to the findings from published data.