Content area experts as authors: helpful or harmful for systematic reviews and meta-analyses?

asking them to peer review the protocol or the review. For reviews involving meta-analyses of raw, individual patient data, it is common practice that investigators from the primary studies co-author the review. Involvement of these experts is considered essential in understanding how the studies were conducted, whether there are any peculiarities in the data, and to correct inconsistencies and errors that may arise from logical queries in the datasets. Their author role is expected given that they “control” the studies and the data. However, if raw data become available to the public, bodies such as the Organisation for Economic Cooperation and Development, the European Commission, and the US National Institutes of Health agree that coauthorship cannot be a condition for using the data.