Reliability of cause of death due to violence from information systems in Belo Horizonte, Southern Brazil

OBJECTIVE: To determine reliability of data encoding for death due to violence; to assess the agreement between cause of death in the Mortality Information System and cause selected from the Forensic Medicine Institute database; and to assess the impact of adding information of non-specified injuries and undetermined death events subsequently obtained from Forensic Medicine Institute in the mortality statistics due to violence. METHODS: A random sample of 411 death certificates due to violence was obtained in Belo Horizonte, Southeastern Brazil, between 1998 and 2000. Based on data from death certificates and Forensic Medicine Institute database, causes of death were coded and the agreement between this information and that from Mortality Information System was assessed. Also, in all certificates including "non-specified injury" and "undetermined death events," the impact of adding information from Forensic Medicine Institute was assessed in the classification of cause of death. RESULTS: Coding agreement was significant (Kappa=0.782; 95% CI: 0.744; 0.819) and of the underlying cause was moderate to significant (Kappa=0.602; 95% CI: 0.563; 0.641). There were 12.9% and 5.7% misclassification of suicides and murders, respectively, for those causes classified as "non-specified injury" and "undetermined death events," which were overall reduced to 47.3% and 59.8% respectively. CONCLUSIONS: There is a need for further improving the process of underlying cause coding and selection. Also medical examiners need to provide more complete death certificates and medical and police information provided with bodies for Forensic Medicine Institute autopsy should be more complete, especially in those cases of road traffic injuries and falls.