Suicide is a complex phenomenon that is influenced by multiple interacting factors. Indeed, it can be overwhelming as an early career suicidologist trying to understand suicide and support those struggling. I, and many others, have the opportunity to have suicide be a part of our research, clinical work, and personal history. How can one make sense of it all? Although it may seem obvious, it cannot be overstated: suicide theory facilitates our understanding of suicide. Theory helps us organize constructs into meaningful taxonomies and purported causal relationships or associations. Under these systems we can create hypothetically universal statements, for example (e.g., ‘A’ leads to ‘B’), collect data, and observe if the data fits or falsifies the theory. That is, should ‘A’ occur and ‘B’ not follow, we have evidence against the truthfulness (i.e., verisimilitude) of a theory . Thus, suicide theories are needed to guide our research in an organized and testable way.
One theory that purports to explain why people have suicidal thoughts and engage in suicidal behavior is the Interpersonal Theory of Suicide (IPTS) . The IPTS states that individuals go through a series of four-interconnected stages, with death by suicide occurring in the final stage. In short, the IPTS focuses on four constructs: thwarted belongingness (a lack of connection with others), perceived burdensomeness (an individual’s sense that others are better off without them), hopelessness about the two former constructs improving, and acquired capability for suicide (increase pain tolerance and reduced fear of death). Despite gaining considerable research and clinical attention since its initial publication in 2005 , it has become a face of controversy [see 4-8]. For example, the IPTS’s falsifiability, or ability to be disproven, and current evidence base have been called into question. Some authors have highlighted their perceived shortcomings of a 2017 meta-analysis  and have gone to extremes as to question the need for a meta-analysis for a theory that has likely not been accurately tested . Interestingly, the 2017 meta-analysis provided a set of recommendations to guide future IPTS studies, which may circumvent some of the perceived criticisms.
Although I initially sat back and watched the IPTS debate unfold, I eventually saw an opportunity to empirically investigate the extent to which the criticisms I have read over the past few years are justified. As such, my supervisor and I designed a study that could test the extent to which the IPTS literature falls victim to outlined criticisms and/or followed recommendation as outlined by the 2017 meta-analysis . Specifically, our team (shoutout to my honour’s student, Matt, and research assistants, Olivia and Hana) completed a review of studies that purported to test the IPTS to determine the extent to which they followed Chu et al.’s  recommendations or safeguarded against commonly cited criticisms (e.g., using alternative ways to measure the IPTS’s constructs, falsifiability).
First, we created a comprehensive codebook and rubric that allowed us to accurately code articles according to the degree to which they followed recommendations or avoided some of the recent criticisms. We practiced using the codebook and rubric on approximately 20 articles to ensure that our team reliably coded the same way. Next, we completed a search using popular databases that contained IPTS-relevant journal articles (e.g., PsychINFO, PubMed) published after the 2017 meta-analysis. We identified and are currently coding the 174 eligible studies regarding the degree to which they adhered to Chu et al.’s  recommendation or circumvented common criticisms [see 4-8]. A small series of preliminary results follow. It is important to note that we are at the tail end of coding and, thus, the following results may not represent the full results. As such, please contact me if you are interested in a copy of the full results upon study completion.
One recommendation was for researchers to branch out from the ubiquitous Interpersonal Needs Questionnaire (INQ) and use alternative ways to measure some of the IPTS constructs . Furthermore, others have commented that that INQ is a poor measure . The preliminary results of our study suggest that the INQ continues to dominate the IPTS literature. Specifically, over 92% of articles since the 2017 meta-analysis used the INQ or a derivative (e.g., a Spanish translation) to measure Perceived Burdensomeness and Thwarted Belonginess.
Another recommendation from Chu and colleagues was to expand the regions from which participants are recruited, historically the United States, to explore the generalizability of the theory . Our preliminary results suggest that the IPTS has been primarily tested on US samples. Specifically, 59% of studies recruiting strictly from the United States. Less than 2% of articles recruited Canadians. In total, participants were recruited from 20 different countries.
The IPTS has shifted how some suicidologists have conceptualized suicidal thoughts and behaviors. Perhaps most importantly, it marked a shift towards ideation-to-action frameworks that attempt to understand how individuals begin to experience suicidal thoughts and then shift to suicidal behaviors. Despite this, some have noted suicidology’s shortcomings by adopted this as the main player of suicide theory. As the debate about the IPTS continues, I hope we don’t lose sight that we are all playing for the same team with largely the same goals. We hope that the results of our described and future studies can help with the progression of theory to help researchers, clinicians, and policy makers better support those struggling with suicidal thoughts and behaviors.
- Popper, K. R. (1959). The logic of scientific discovery. New York: Routledge Classics.
- Van Orden, A. K., Witte, K. T., Cukrowicz, C. K., Braithwaite, R. S., Selby, A. E., & Joiner, E. T. (2010). The interpersonal theory of suicide. Psychological Review, 117(2), 575-600. https://doi.org/10.1037/a0018697
- Joiner, T. (2005). Why people die by suicide. Harvard University Press.
- Paniagua, F. A., Black, S. A., Gallaway, S. M., & Coombs, M. A. (2010). The Interpersonal-Psychological Theory of Attempted and Completed Suicide: Conceptual and Empirical Issues. AuthorHouse.
- Hjelmeland, H., & Knizek, L.B. (2020). The emperor’s new clothes? A critical look at the interpersonal theory of suicide. Death Studies, 44:3, 168-178. 10.1080/07481187.2018.1527796
- Klonsky, E. D. (2019). The role of theory for understanding and preventing suicide (but not predicting it): A commentary on Hjelmeland and Knizek. Death Studies, 44(7), 459–462. https://doi.org/10.1080/07481187.2019.1594005
- Smith, P. N., Schuler, K., Fadoir, N., Marie, L., & Basu, N. (2019). Socio-ecological context and the interpersonal theory of suicide: A response to Hjelmeland & Knizek. Death Studies, 44(9), 547–551. https://doi.org/10.1080/07481187.2019.1586799
- Abrutyn, S., & Mueller, A. S. (2019). Toward a robust science of suicide: Epistemological, theoretical, and methodological considerations in advancing suicidology. Death Studies, 1–6. https://doi.org/10.1080/07481187.2019.1660081
- Chu, C., Buchman-Schmitt, J. M., Stanley, I. H., Hom, M. A., Tucker, R. P., Hagan, C. R., Rogers, M. L., Podlogar, M. C., Chiurliza, B., Ringer, F. B., Michaels, M. S., Patros, C. H. G., & Joiner, T. E. (2017). The interpersonal theory of suicide: A systematic review and meta-analysis of a decade of cross-national research. Psychological Bulletin, 143(12), 1313–1345. https://doi.org/10.1037/bul0000123
- van Orden, K. A., Cukrowicz, K. C., Witte, T. K., & Joiner, T. E. (2012). Thwarted belongingness and perceived burdensomeness: Construct validity and psychometric properties of the Interpersonal Needs Questionnaire. Psychological Assessment, 24(1), 197–215. https://doi.org/10.1037/a0025358