Introduction: Suicide bears a significant public health
impact worldwide, and there is a need for better identification
of suicide risk and protective factors and more accurate
prediction of its development. The aim of the present thesis was
to promote suicide prevention through: (1) better understanding
and identification of interpersonal risk factors for suicide, as
outlined by a recent predictive model of suicide: the
Interpersonal Psychological Theory of Suicide (IPTS; Joiner,
2005; Van Orden et al., 2010), and (2) building interpersonal
strengths. Methods: A systematic review was conducted to identify
support for the IPTS predictions regarding suicide ideation and
suicide attempt. Based on the results of this review, several
studies were conducted to fill critical gaps in the literature
base. This included: (a) a latent class study of 1,321 adults to
test the generalisability of the IPTS predictions in a community
sample, (b) a longitudinal study in an Australian clinical sample
(n = 331) to test the IPTS predictions over time in a high-risk
population, (c) a study to develop and validate a new self-report
measure for thwarted belongingness (TBS) against the
Interpersonal Needs Questionnaire Thwarted Belongingness subscale
(INQ TB; Van Orden, Cukrowicz, Witte, & Joiner, 2012) and (d) a
pilot study to investigate the feasibility of a university-based
peer-support walking program in contributing to decreased
interpersonal suicide risk in Australian university students.
Results: The systematic review found mixed evidence across the
theory’s main predictions. The effect of perceived
burdensomeness on suicide ideation was the most tested and
supported relationship. The theory’s other predictions,
particularly in terms of critical interaction effects, were less
strongly supported. Across studies testing the IPTS predictions
(Chapters 3-5), the role and specificity of the two-way
interaction between TB and PB on suicide ideation was supported
in two community-based samples, but not supported
cross-sectionally or longitudinally in a clinical sample. No
support was found for the IPTS three-way interaction prediction.
However, associations between the interpersonal risk factors and
suicidality were consistently supported across the studies.
Findings from the pilot controlled trial (Chapter 6) indicated
that a university-based peer-support walking program contributed
to increased levels of positive friendship social support
(Cohen’s d = 0.82) and decreased levels of psychological
distress (Cohen’s d = -0.32) in university students.
Conclusions: Mixed findings regarding the two- and three-way IPTS
interactions highlight the critical need for additional IPTS
studies designed with the aim of overcoming existing
methodological limitations before the full extent of the
theory’s theoretical and clinical utility can be determined.
Support for the interpersonal risk factors as main effects
suggests that they may serve as valuable targets for suicide
prevention and intervention more broadly. Future research
utilising the best available and validated measures of the
interpersonal risk factors is needed for better prediction of
interpersonal suicide risk, and for use in the design and
evaluation of connectedness-based suicide prevention/intervention
programs to promote interpersonal strengths in the community