Why do we agree to disagree? Agreement and reasons for disagreement in judgements of intentional self-harm from coroners and a suicide register in Queensland, Australia, from 2001 to 2015

Suicides are likely to be underreported. In Australia, the National Coronial Information System (NCIS) provides information about suicide deaths reported to coroners. The NCIS represents the findings on the intent of the deceased as determined by coroners. We used the Queensland Suicide Register (QSR) to assess the direction, magnitude, and predictors of any differences in the reporting of suicide in Queensland. Therefore, we conducted a consecutive case series study to assess agreement and variation between linked data from the NCIS and QSR determinations of suicide for all suicide deaths (N = 9520) in the QSR from 2001 to 2015 recorded from routinely collected coronial data. The rate of concordance between the QSR and NCIS for cases of intentional self-harm was 92.7%. There was disagreement between the findings in the data, since 6.3% (n = 597) were considered as intentional self-harm in the QSR but not in the NCIS, and, less commonly, 0.9% (n = 87) were considered intentional self-harm in the NCIS but not in the QSR. Overall, the QSR reported 510 more suicides than the NCIS in 15 years. These findings indicate that using suicide mortality data from suicide registers may not underreport suicide as often.