Background: Death certificates are the only source of information on the underlying cause of death in more than 90 % of cases. Supplementary information is available for only a small proportion of them, as a rule from a medical or forensic autopsy. We wished to investigate how frequently the findings of medical autopsies influence determination of the underlying cause of death.
Material and method: Using the Norwegian Cause of Death Register as our basis, we determined from the death certificate the underlying cause of death for deaths for which a medical autopsy was carried out in 2005. Then we investigated whether the underlying cause of death was changed when we took account of the autopsy findings.
Results: There were 41,152 deaths in Norway in 2005. The Cause of Death Registry received the results of medical autopsies for 1 773 persons who died at the age of 2 or older. Autopsy findings led to changes in the underlying cause of death in 1,077 cases (61 %). In 567 cases (32 %), the change was a major one, resulting in a change in the ICD 10 chapter for cause of death. The percentage of changed causes of death was greatest for the youngest and oldest age groups and for women.
Interpretation: Medical autopsies provide an important corrective to the determination of underlying cause of death.