The proposed linkage of data on abused children is based on a belief that some abusive parents manipulate health systems to make it harder for services to recognise patterns of injury. If this is true - and it seems plausible - then those same parents will be motivated to manipulate the new system for similar reasons.

One unintended, but entirely foreseeable, consequence is that some of those children, some of the time, will be denied health care that they would otherwise have received. For those who become non-attenders there will be no benefit from data linkage because the data will not be collected, but significant harm may result from missed treatment.

Traditionally healthcare has been provided confidentially in order to encourage such patients to present for treatment. As medical information is increasingly used for the prevention and detection of crime a point will be reached where the harm caused by deterring people from treatment will outweigh the benefit of reducing harm

Competing interests: None declared