Discussion

This study reveals key differences in completed suicide recorded in younger compared to older adolescents, and male compared to female adolescents. Previous studies have demonstrated that young people who die from suicide are significantly more likely than the general population to have a serious mental health illness.^2,3,25 This is consistent with our study, in which 40% of adolescents had a formally diagnosed mental illness, which is much higher than the reported 14% in the general Australian population.^26,27However, our study did not reflect previous adolescent suicide studies that demonstrated the prevalence of diagnosed mental illness increasing with age.^7,11 The lack of difference by age group in our study may be because there was actually a high rate of mental illness (41%) in the younger adolescent group. This could suggest that adolescents who are diagnosed at a younger age with mental illness may be at increased risk for suicide.

The lifetime prevalence of deliberate self?harm in adolescents has been estimated at 10-18%, with higher rates in females compared to males.^27-30 Our study demonstrated that adolescents who died from suicide had higher rates of previous deliberate self?harm compared to the general population. Our study's results were consistent with previous studies demonstrating that male adolescents are more likely to die by suicide than females.^2,3,31 There is a 'gender paradox' of suicide, in which suicidal behaviour and deliberate self?harm is more common in females, but completed suicide is more common in males.² The results of our study appear to be in line with this 'gender paradox'.

Known associations and risk factors for both self?harm and suicide in adolescents are similar and often overlap. These factors include low socioeconomic status, restricted educational achievement, parent separation, adverse childhood experiences, interpersonal difficulties, mental disorders, and drug and alcohol misuse.^2,3,31,34Deliberate self?harm in adolescents can be a gateway to subsequent suicidal behaviour.³³ In comparison to studies in the general population, which demonstrate the prevalence of deliberate self?harm is higher in older compared to younger adolescents,^27,28 our study showed that previous self?harm was relatively more prevalent in younger adolescents who died by suicide. This finding is consistent with one UK study³² and warrants further analysis, as it suggests that younger adolescents with self?harming behaviours may be at increased risk of subsequent suicide. Adolescent presentations to hospital after self?harm often involve disclosure of suicidal intent,³⁵ and are a means for flagging increased risk for subsequent engagement with mental health professionals.

In 2016, 5.1% of Australians aged 15-19 years were classified as NEET.³⁷ Our study showed rates of NEET were much higher in adolescents who died by suicide, with a prevalence four times higher for older adolescents, and three times higher overall. Other studies have shown even higher rates of disengagement in education or employment, with up to one in five school?aged children who completed suicide not attending school at the time of their death, and one?third of adolescents being unemployed.^38-40 In line with our hypothesis, this may suggest that participation in education, training or employment may be a protective factor, and conversely that adolescents classified as NEET may be at increased risk for suicide. It is recognised that a lack of formal educational qualification is a risk for suicide.²⁵ Unemployment and disengagement with education are likely to have detrimental effects on mental health and emotional wellbeing. The reasons why engagement in education and training or employment are likely to be important protective factors needs to be further explored.

Consistent with our results, previous studies have demonstrated that hanging is the most frequent method in adolescent suicides, with this method decreasing with age.^7,15,43 Previous studies have demonstrated inconsistent findings regarding evidence of intent in adolescent suicide. One psychological autopsy found the majority of young people who die from suicide communicate their intent, but not usually on the day of death.⁴¹ Other studies describe younger adolescents who died from suicide as being more likely to have demonstrated suicidal behaviour or ideation than the general population,^15,42whereas others have found younger adolescents are less likely to communicate suicidal intent.^9,15 Another study showed that approximately one?third communicated suicidal intent in the preceding 12 months, with no observable difference between age groups.⁷ In our study, intent (both implicit and explicit) was communicated in almost half of all cases, with no significant difference between age or sex. The reasons for such differences between studies may be due to the definition of intent - particularly implicit intent - being somewhat subjective, and parameters for timing (e.g. previous 24 hours compared to previous month) may have differed between studies.

Compared to the general population, young people who die from suicide are more likely to have had exposure to stressors, both chronic and acute.^3,7,31,42,44 These stressors are multiple and varied and include interpersonal conflict, relationship problems, bullying and abuse. In our study, peer conflict and bullying was seen at higher rates in both younger and female adolescents. There is strong evidence highlighting bullying as a risk factor for suicidal behaviour in adolescents,^45-49with a particular impact on female suicide.⁴⁷ However, to our knowledge, no previous studies have specifically demonstrated this concerning relationship between increased incidence of bullying in younger adolescent suicide. Our finding of almost six in 10 young females who died by suicide being exposed to abuse also warrants attention. Compared to the general adolescent population, children and adolescents who complete suicide are significantly more likely to have experienced physical, sexual or emotional abuse.^42,50,51 Abuse in all its forms is harmful and potentially amenable to reduction. This study may add weight to efforts that contribute to abuse prevention and post?abuse supports. Relationship breakdown, interpersonal loss and rejection are also common precipitants to youth suicide,⁴¹ and the prevalence of relationship problems in suicide has been shown to increase with age.^7,11 Our study did not observe this increase by age, but this may be because there was actually a relatively high proportion (29%) of younger adolescents exposed to partner conflict. This may suggest an association between partner conflict in younger adolescents and risk of suicide.

In Australia, the legal age for purchase and consumption of alcohol is 18 years. Alcohol abuse is less common in younger children compared to adolescents who complete suicide,^14,52 and is consumed less frequently prior to death compared to older adolescents.^9,15 Our study may reflect this trend, with younger adolescents having alcohol on post?mortem toxicology at almost half the incidence of older adolescents.

Additional Research Methods . Identify the data analysis methods used and explain why the methods are appropriate based on the research question. . Discuss the potential weaknesses of the data analysis methods used. Support your discussion with examples from the study. . Describe the key demographics of the population sampled and identify the inclusion and exclusion criteria for participants. Key Findings: . State the results of the research, describing how the researchers determined whether the results are statistically significant. . Describe the differences in the results between the groups in the study and support your description with examples from the study