Guidelines for sharing individual level patient data

EXCLI Journal has long encouraged authors to make anonymized individual-level data available as supplementary material whenever this can be done responsibly. Recent discussions, however, have raised concerns about whether even anonymized laboratory data from individual patients may create unacceptable privacy risks. We examine this question from both a scientific and a practical perspective. We first consider why underlying data should be preserved and shared: they can support verification of published results, allow alternative analyses, and preserve information for future research. We then stress-test the privacy argument by constructing hypothetical scenarios in which a published table of individual laboratory values could lead to identification of a participant, disclosure of previously unknown health information, and concrete harm. These scenarios show that such a chain of events is possible, but that its likelihood depends strongly on the characteristics of the dataset and on information already available to a potential attacker. Small datasets containing rare, distinctive, or potentially stigmatizing findings require particular caution. Based on this analysis and the existing literature, we propose the following principles for EXCLI Journal: appropriately anonymized individual-level clinical measurements and data derived from biological samples should generally be shared when the residual risk is low and the scientific value is substantial. More sensitive or distinctive datasets may require aggregation, removal of potentially identifying variables, or controlled access. Authors invoking institutional restrictions on public data sharing should provide the relevant policy to the editors, and such restrictions should not prevent editors and reviewer from accessing the underlying data for verification. Our aim is not to eliminate every conceivable risk, but to establish a proportionate approach that protects participants while preserving valuable data for future science.