A sixth excuse for not sharing data that is available to those who do research with patients is patient confidentiality. One case of private information of a patient being exposed could, some researchers argue, bring data sharing to a halt. It is a “never event” that must be avoided even if huge benefits are foregone by not sharing data. Patient confidentiality must be guarded, and most of the time it’s easy to do so by anonymising data and removing data on, for example, place and time. It’s true that small risks remain because of rare conditions and events and because of “jigsawing” (combining datasets to break confidentiality), but these small risks can be explained to patients, who will almost always consent to their data being made available in anonymous form. With datasets that are already collected patients might be asked to give retrospective consent.
Patient confidentiality is the reason that authors of a controversial trial on treatment of chronic fatigue syndrome give for not sharing their data, but inevitably they look as if they are hiding something
