Procedure

Age-specific suicide rates (ASSRs) were calculated as the average yearly number of suicide deaths per 100,000 persons among Aboriginal and Torres Strait Islander young people in Queensland, Australia, from 2001 to 2015. This study examined suicide rates for young people due to the larger suicide disparities for this age group compared to older Aboriginal and Torres Strait Islander cohorts.10,11 Young people were aged between 15–24 years following the United Nations definition of this age group.43 To compare suicide rates in different areas, rate ratios (RR) and their 95% confidence intervals and exact probability levels were calculated.

The data analyses comprised three major phases. The first phase examined suicide rates in areas with high as compared to low levels of community-level cultural connectedness using two indicators; cultural social capital and Indigenous language use. The second phase examined suicide rates in communities with three types of community-level risk factors; (1) high as compared to lower rates of discrimination, (2) high as compared to low socioeconomic disadvantage, and (3) geographical remoteness as compared to urban environments. The third phase examined suicide rates in communities with high as compared to low levels of cultural connectedness indicators (cultural social capital and Indigenous language use) in areas with elevated risk at the community level (high rates of discrimination, high socioeconomic disadvantage and geographical remoteness). Table 1 includes the full list of variables and classifications used. Correlations between community-level factors are also presented.

Table 1. Variable classification and age-specific suicide rates (ASSRs) of Aboriginal and Torres Strait Islander young people (15–24 years) by sex, age, cultural social capital, Indigenous language use, discrimination, Index of Relative Socioeconomic Advantage and Disadvantage (IRSAD), and Remoteness Areas, Qld, 2001–2015.

Variable

Classification

N (SA2s)

N (Suicides)

Rate

95% LL

95% UL

Cultural social capital

   Low

Lowest 1/3

166

163

55.35

47.18

64.53

   High

Highest 2/3

315

63

34.75

26.7

44.47

Language use

   Low

<5% of residents

459

185

42.62

31.2

56.84

   High

>5% of residents

51

46

48.12

41.44

55.58

Discrimination

   High

>30% of residents

218

134

50.74

42.51

60.09

   Low

<30% of residents

263

92

43.46

35.40

53.3

IRSAD

   Low

Three lowest-ranked quintiles (Lowest 60%)

313

203

49.64

43.05

56.96

   High

Two highest-ranked quintiles (Highest 40%)

198

28

33.54

22.28

48.47

Remoteness Areas

Regional & remote

Inner regional, Outer Regional, Remote, Very Remote

234

173

51.79

44.36

60.11

Metropolitan

Major Cities

292

58

36.62

27.80

47.34

Note: Cultural Social capital index scores available for 481 SA2s; Synthetic estimates of discrimination percentages available for 481 SA2s; Synthetic estimates of Indigenous language use percentages available for 510 SA2s; IRSAD indices available for 512 SA2s. 95% LL 95% Confidence interval lower limit, 95% UL 95% Confidence interval upper limit. Data sources

Queensland Suicide Register (QSR). The QSR is a public health surveillance suicide mortality database which includes all suspected and confirmed suicides of Queensland residents of all ages from 1990 to 2017.11 The QSR only had records until 2015 at the time the analysis occurred. The QSR sources data from police reports from the Queensland Police Service; and post-mortem examinations, toxicology and coronial reports from the National Coronial Information System (NCIS).11 The Queensland Registry of Births, Deaths and Marriages supplies information on Indigenous status missing from primary data sources or where the police mis-identify the person. The QSR includes information on a wide range of demographic, psychosocial, psychiatric, medical, contextual and behavioural aspects of suicide cases. This information is used to classify the probability of suicide as either ‘unlikely’, ‘possible’, ‘probable’ or ‘beyond reasonable doubt’ using a decision tree.11 This study included suicides classed as ‘probable’ or ‘beyond reasonable doubt’. This study used data from the QSR on all suicides of Aboriginal and Torres Strait Islander young people age 15–24 years during the period 2001–2015 in Queensland.

The last known or usual residential address recorded in the QSR was further coded into Statistical Area Level Two (SA2) for this study to analyse rates at the community level. To calculate ASSRs by Statistical Area Level Two (SA2) the 2011 Census was used as the closest Census to the midpoint of the analysis period. SA2 is part of the Australian Statistical Geography Standard used in the Census. There were 526 Queensland SA2s in the 2011 Census. Population data were obtained from the Queensland Government Statistician's Office (QGSO) to calculate ASSRs. While it is acknowledged that significant cultural, historical and social differences exist between the many First Nations on these lands, due to the limitations of available population denominator data, which does not further disaggregate, results presented include all Aboriginal and Torres Strait Islander individuals.

Australian Standard Geographical Classification - Remoteness Areas (ASGC-RA). The Remoteness Areas measure remoteness by the accessibility of areas to goods and services using five categories - major cities, inner regional, outer regional, remote, and very remote.44 Inner regional, outer regional, remote and very remote were merged into a single variable ‘Regional and Remote areas’ for comparison with ‘Metropolitan areas’ (major cities) due to data sparsity.

Index of Relative Socioeconomic Advantage and Disadvantage (IRSAD). The IRSAD is a SEIFA (Socio-Economic Indexes for Areas) index ranking areas in Australia and Queensland according to comparative socioeconomic advantage and disadvantage and includes variables related to education (year 11 or lower), occupation (professional, management) disabilities, overcrowded housing and income.45

SA2 Social Indicators for the Indigenous Population (Synthetic estimates). Estimates were accessed from the Australian Urban Research Infrastructure Network (AURIN) system. The National Centre for Social and Economic Modelling (NATSEM) produces these synthetic estimates using a spatial microsimulation model combining demographic information from the 2011 Census at the SA2 level with the richer data from the 2008 National Aboriginal and Torres Strait Islander Social Survey (NATSISS) to gain reliable small-area estimates of Indigenous social indicators. The NATSISS collects information on demographic, social, cultural, environmental and economic indicators, including geography, language and cultural activities, social networks and support, health and wellbeing, education, employment, income and personal safety. It is completed by Aboriginal and Torres Strait Islander residents aged 15 years and older.46 Due to the sensitivity and potential for identification, confidentialised unit record files (or CURFs) from the survey dataset were unavailable. Instead, a synthetic unit record file of Aboriginal and Torres Strait Islander residents built with observations summing to the population totals from the survey census was extracted using the ABS Survey Census Tablebuilder system and the information from the NATSISS were imputed using regression technique from the ABS secured Remote Access Data Laboratory.47 A spatial microsimulation approach was then applied to this synthetic unit record file using a generalised regression reweighting algorithm that reweights the synthetic unit record file to small-area Census benchmarks at SA2 level. These benchmarks included income, age, sex, education and other demographic items (see 48 for the complete benchmarks list). The results were validated against the aggregated NATSISS survey data. The model automatically eliminates any SA2 that fails to achieve the threshold of acceptable error (the Total Absolute Error from the model is greater than the population of the SA2), in which case the model would not provide an estimate.47, 48 The SA2s in Queensland that did not meet the threshold were predominantly industrial and commercial areas in Brisbane.

The indicators selected for this study from this model (and originally from the NATSISS 2008) were:

The cultural social capital index, assessing cultural aspects of social capital such as involvement and attendance in cultural events, ceremonies or organisations, sporting, social or community activities, contact with family or friends and the proportion of friends identifying as Aboriginal and Torres Strait Islander people. This index also includes the ability to get or give support outside the household and comfort in contributing to family/community. Index scores can range from −1 to 1 and were available for 481 of the 526 Queensland SA2s (as seen in Table 1). In this study sample, scores ranged from 0.000 to 0.323. SA2s with the highest two-third scores were compared to those with the lowest-thirds scores on the cultural social capital index (above and below 0.080).

Indigenous language use score reflects the percentage of Aboriginal and Torres Strait Islander residents who report speaking an Indigenous language in the home. The proportion of the First Nations population speaking an Indigenous language ranged from 0% to 96.4%. Due to the positively-skewed language use distribution, areas were delineated as high and low based above and below 5% of Aboriginal and Torres Strait Islander persons speaking an Indigenous language.

Discrimination score reflects the percentage of Aboriginal and Torres Strait Islander residents reporting discrimination in the past 12 months. The scope includes discrimination in the workplace, community, educational institutions, recreational settings, court settings, treatment by the police, health professionals or government agency staff when seeking any public services. In these SA2s, between 9.4% and 50.9% of the Aboriginal and Torres Strait Islander population reported discrimination in the previous year. Areas with high levels of discrimination were those in which 30% or more of the population reported discrimination in the last year.