Risk Factors, Protective Factors, and Risk Patterns for Suicide in Greenland: A systematic approach based on registers and existing knowledge

Introduction
Over the past century, Greenland has witnessed a significant transformation in its suicide rates. Initially, from 1901 to 1960, suicide was a rare occurrence, with rates ranging from 0 to 3.5 suicides per 100,000 people annually. However, a seismic shift occurred after intensive modernization efforts in the 1950s and 1960s. The suicide rate surged dramatically, stabilizing at a persistently high level from 1980 onward, with an average of 96 suicides per 100,000 people annually. Contrary to suicide trends in many Western countries, it is the youth who die by suicide, contributing to a life expectancy that is ten years lower than in Denmark. Arctic Indigenous populations, in general, experience high rates of suicide. These high rates are related to social disruption caused by colonization and rapid cultural and societal changes.

Aim
The overall aim of this thesis is to identify and investigate relevant risk factors and protective factors for suicide and related behaviors among Greenland Inuit using national registers and a systematic review of the scientific literature. The specific aims are:

- To generate a comprehensive overview of risk factors and protective factors for suicide and suicidal behavior in Greenland based on published peer-review papers (Paper I).

- To define suicide rates in Greenland according to age, birth cohort, period, sex, and place of residence from 1970 until 2018 (Paper II).

- To investigate the association between sex and suicide methods over time (Paper II).

- To investigate how suicide-related loss of a close family member in childhood is associated with later suicide incidence (Paper III).

Methods
Paper I was a systematic review including all peer-reviewed literature on risk factors and protective factors for suicide and suicidal behavior among Greenland Inuit. No restrictions were made on eligible study designs. Based on searches in PubMed and PsycINFO, 420 peer-reviewed papers were identified and reviewed by at least two authors, resulting in the inclusion of 15 papers for the narrative synthesis. Due to a high degree of heterogeneity, no meta-analyses were conducted. All included papers were quality assessed. Papers II and III were nationwide studies based on register data from the central population register and the register of causes of death. Paper II further included national census data from 1970 and 1976. Both study populations were Greenland Inuit, and paper II included 2,265,676 person-years from 1970 until 2018, while paper III included 25,663 people born in Greenland between 1983 and 2012. Paper II analyzed suicide according to sex, age, birth cohort, calendar time, region of residence, and suicide method. Paper III analyzed suicide incidence according to the loss of a close family member before the age of 10 years. Analyses in both studies were based on Poisson regression

Results
The average suicide rate from 1970 to 2018 was 86 suicides per 100,000 people annually. Most suicides were seen in young people aged 15-24 years, and there was a geographical clustering of suicide with the highest rates in East Greenland. The high rates of suicide among Greenland Inuit are associated with its colonial past, rapid modernization, and societal disruption resulting in intergenerational trauma and high prevalences of ACEs. Risk factors for suicide cluster among people with lower social status and limited access to occupational opportunities, education, and other living conditions that are key determinants of well-being. Risk factors that often co-exist are related to dysfunctional families, problems with alcohol consumption, and the prevalence of ACEs. The systematic review uncovered that little is known about protective factors in Greenlandic research about suicide, but among men, being married and having children was protective. Other protective factors are being born in generations between 1900 and 1950 and having many household assets. Losing a close family member during childhood increases the suicide incidence rate ratio compared to those who did not experience any loss, and the increase is highest in cases where an individual lost a mother to suicide.

Conclusion
This thesis has elucidated the complexity of risk and protective factors associated with suicide among the Greenland Inuit, while also contextualizing the emergence and acceleration of these factors within a historical framework. Suicide risk is associated with socioeconomic status, access to resources, and better living conditions, and I argue that there is a syndemic effect. The high prevalence of risk factors in Greenlandic society partly explains the high rates, and these risk factors often cluster. Addressing social and geographical inequality is essential, and future research and prevention should focus on promoting protective factors such as cultural strengths and thriving communities.