. 2020 Nov 20;29-30:100631. doi: 10.1016/j.eclinm.2020.100631

Table 1.

Table of definitions of included variables.

Variable	Definition and ascertainment	Variable
Age^a	Determined by the NCIS core dataset	Demographic
Sex^a	Determined by the NCIS core dataset	Demographic
Aboriginal or Torres Strait Island status^a	Determined by the NCIS core dataset	Demographic
Student status^a	Determined by the NCIS core dataset	Demographic
Employment status^a	Determined by the NCIS core dataset	Demographic
Socioeconomic disadvantage (SEIFA) ^a	Determined by SA2 place of residence. The variable represents people who resided in regions that were identified in the bottom 20th percentile of socioeconomic disadvantage determined by the Australian Bureau of statistics Socio-economic index for advantage and disadvantage based on Statistical Area level 2.	Demographic
Remoteness^a	Determined by SA2 place of residence. The variable represents people who resided in regions that were identified as remote or very remote in the NCIS.	Demographic
Distance between the residence of index and exposed cases^a	Based on the geographic centroid of place of residence based on SA2 geography recorded in the NCIS core dataset.	Demographic
Parent separation^a	Based on informant reports that the person's biological or adoptive parents were divorced or separated at the time of death or otherwise married or living in a de facto relationship. A definition of parent separation includes indirect evidence (e.g., narrative descriptions that indicate the young person lived with their mother).	Social
Living alone^a	Based on informant reports or other documented evidence (e.g., police observation) that the person lived alone (e.g., the absence of roommates or other cohabitating household members).	Social
History of abuse and/or neglect^a	Based on an informant report or other documented evidence (e.g., police statements) that the person had been sexually, physically or emotionally abused, or that the person had experienced neglect in their family home. Excludes informant reports of suspected abuse or neglect.	Social
Exposure to domestic violence^a	Based on an informant report or documented police statements that the person had experienced violent or aggressive behaviour within the home. Includes exposure during childhood to domestic violence between parents.	Social
Relationship breakdown with an intimate partner (past 1 month) ^a	Based on an informant report that the person had a relationship breakdown with an intimate partner. Includes teenage boyfriend/girlfriend relationships and online relationships.	Social
Peer conflict (past 12 months) ^a	Based on an informant report that the person experienced relationship problems (e.g., arguments or physical confrontations) with their peers, or those in their friendship circle, in the 12 months prior to their death.	Social
Family conflict (past 12 months) ^a	Based on an informant report that the person had experienced relationship problems (e.g., arguments or physical confrontations) with their family members. Includes conflicts in the family environment that described the person had feelings that they were not able to meet family expectations.	Social
Diagnosed or undiagnosed mental ill health^a	Based on documented medical evidence that the young person: (1) had a psychiatric diagnosis prior to their suicide; OR (2) the young person was being treated by a medical practitioner (e.g., GP, psychologist, psychiatrist) for mental-illness; OR (3) an informant reported that the young person was being treated for mental health symptoms AND results from the NCIS toxicology report described the presence of therapeutic levels of psychotropic medication (e.g., antidepressants) at or around the time of death; OR (4) the young person told an informant that they had mental health problems, but it was not otherwise verified by official records during the police or coroner investigation or evidence of therapeutic levels of psychotropic medication in the toxicology findings.	Clinical
Suicide attempt or self-harm (irrespective of intent) ^a	Based on an informant report or documented medical evidence that the person had made a suicide attempt or had self-harmed in the 12 months prior to their suicide. Includes presenting to healthcare services (e.g., ED) for a suicide attempt, informant descriptions of self-harm or suicide attempts, as well as indirect evidence from autopsy reports (e.g., the autopsy reported evidence of self-inflicted injuries or evidence of healing wounds from self-inflicted injuries such as abrasions to the wrist or consistent with cutting). Does not include informants reports of suspected self-harm or suicide attempt.	Clinical
Discharged from the Emergency Department (ED) for mental health symptoms^a	Based on an informant report or documented medical evidence that the person presented to the ED prior to their suicide for reasons primarily related to mental health symptoms (including self-harm) and was discharged from the ED. Excludes presentations to the ED for reasons unrelated to mental health (e.g., suspected appendicitis) or informant reports of ED presentations for reasons unknown (e.g., may or may not have presented to the ED primarily because of mental health symptoms).	Clinical
Illicit substances detected in toxicology report^a	Based on toxicology findings that indicated the presence of illicit substances (e.g., methamphetamine, cannabis, cocaine, MDMA) and/or their by-products demonstrating recent use of illicit substances. Includes substances of misuse (e.g., taurine from paint, petroleum from petrol).	Clinical
Binge Drinking^a	Based on an informant report that the young person had been drinking excessively in the month prior to their death.	Clinical
Alcohol intoxication^b	Based on toxicology findings that indicated a blood alcohol concentration >1500 mmol/l. Excludes alcohol readings from urine samples and toxicology reports that indicated that the alcohol concentration was likely to be influenced by post-mortem changes (e.g., decomposition).	Circumstances of suicide
Method of suicide ^b	Determined by coroner report and ICD-10 code for cause of death.	Circumstances of suicide
Suicide note ^b	Based on an informant report or police observation that the person had written a suicide note that indicated their intent to die. Includes goodbye text messages and emails sent by the deceased prior to their suicide.	Circumstances of suicide
Told someone they wanted to die ^b	Based on an informant report that the person expressed suicidal ideation or indicated that they wanted to take their own life or die. Includes written, verbal communication, text communication and email communication.	Circumstances of suicide
Communicated about suicide on social media ^b	Based on an informant report or evidence of online activity that showed the person posted content about suicide or expressed suicidal ideation on social media (e.g., posted a suicide note on Facebook, or shared a post that indicated they were suicidal).	Circumstances of suicide
Searched the internet for suicide methods ^b	Based on the police or coroner report that described evidence of internet queries about suicide or the person had visited a website that described methods of suicide.	Circumstances of suicide
Date of death	Based on the date (dd/mm/yyyy) of death. Date of death was determined by the coroner and recorded in the NCIS core dataset.	Circumstances of suicide

Included in the analysis of assortative relating.

Included in the analysis of imitative suicidal behaviour.