Suicide decline in Australia: where did the cases go?

Objectives: To describe the causes of death codes assigned in Australian Bureau of Statistics (ABS) mortality data to deaths in Australia from 2000 to 2005 that were coded as intentional self-harm (suicide) in the National Coroners Information System (NCIS). Methods: Data for deaths in the period mid-2000 to end-2005 were obtained from the National Coroners Information System database (NCIS). We selected cases recorded in the NCIS as having intent at completion = intentional self-harm. The record linkage was done by the ABS and NCIS and did not form part of this project. Results: During the study period, 12,786 deaths recorded in NCIS were assigned intent at completion = intentional self-harm. Of these, 9,937 (77.7%) had been assigned ICD-10 underlying cause of death codes in the range normally reported as suicide (X60-X84), 1,135 had been assigned other ICD-10 codes and the remaining 1,714 (13.4%) NCIS records did not hold any ICD-10 codes. Conclusions: These findings confirm that routine mortality data have underestimated suicide mortality in Australia in recent years probably due to incomplete coroner data being available to ABS coders. Certain types of unintentional injury deaths have been over-estimated. Incomplete linkage of NCIS and ABS data in the source data used for this project complicates calculations of adjusted estimates and trends.