Most deaths around the world are certified, registered and then ‘coded’ for statistical purposes. Misclassified (‘hidden’) suicides are deaths assigned an ICD code that is either erroneous or that should never be specified as a cause of death. Public health strategies depend on provision of accurate mortality statistics. Suicides are under-counted, largely through misattribution to natural disease, accident, ill-defined or unknown cause (code R99) or an event of undetermined intent. Proportions of suicides misclassified to each of these codes vary between nations. It is recommended that psychological or verbal autopsies be used when investigating external deaths of uncertain cause or intention, and some R99 deaths. This applies in Britain and wherever unusual patterns of deaths could signal hidden suicides – exemplified by high rates of drug deaths in North America.
