Lack of overlap and large discrepancies in the characteristics of the deceased in two sources of drug death. A linkage study of the Cause of Death and the Police Registries in Norway 2007-2009

BackgroundRegistries for drug deaths may include different persons and provide different characteristics of the deceased. The aim of this study was to establish whether a database of drug-induced deaths (Cause of Death Registry (CDR) using the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) definition and the Police registry of drug deaths) included the same persons and provided the same characteristics of the deceased and thus yielded the same information for establishing targeted prevention measures.MethodsNotifications from 2007 to 2009 were drawn from the CDR and the police registry of drug deaths and the unique Norwegian personal identification number was used to match the registrations.ResultsThe two sources of drug deaths yielded 1384 registrations, encompassing 929 individuals of whom only 49% were included in both registries. A large proportion of the deceased (40%) were not listed in the police registry. This group was older (mean age 43 years vs. 35 years); dependence and suicide were listed more often as cause of death (33% vs. 8%); and heroin was listed less often as the type of drug causing death (24% vs. 67%) than those included in both registries. In particular, among women not included in the police registry, the cause of death was identified with much greater frequency as pharmaceuticals with morphine or codeine (47% vs. 16%).ConclusionThe large discrepancies in size, overlap, and characteristics of the deceased included in two sources of drug death imply that prevention measures based on the two sources will differ.