Background: Norwegian media often claim that a disproportionately high number of deaths in Norway are caused by overdoses. The police statistics in 2007 showed an increase in the number of overdose deaths, and many media postings focused on this in autumn 2008. In this paper we investigate the basis for those police statistics and discuss problems associated with calculating deaths caused by use of illegal substances.
Material and methods: The police registries of overdose deaths were anonymized in the period 2005-2007. The deaths were coded according to type of substance involved.
Results: In 2007, 62 deaths were coded as overdose deaths without any use of illegal substances; in 2005 this was the case for 24 deaths and in 2006 for 25. The maximum proportions of deaths in Oslo that can be related to heroine were 91.7 % in 2006 and 57.8 % in 2007. In the rest of the country the corresponding numbers were 68.8 % and 62.2 %.
Interpretation: A considerable number of deaths without use of illegal drugs are counted as overdose deaths. The increase found in Norway in 2007 is largely explained by changes in registration routines in Oslo. The high number of overdose deaths can partly be explained by methodological problems with registration. Nevertheless, the number of overdose deaths is high and of major concern. Causes of deaths should be discriminated better in the overdose statistics in order to improve the preventive strategies.