Intolerance of uncertainty – the rise and spread of a measure to a construct: A protocol for a systematic bibliometric review
Creators: name: Lowenna Jordan
name: Gan, Sean Dong Wei
name: Emily-Rose Cross
name: Freeston, Mark H
Publisher: name: OSF Registries
Year: 2023
Subjects: subject: Social and Behavioral Sciences
subject: bibliometric review
subject: intolerance of uncertainty
subject: transdiagnostic

description: The Intolerance of Uncertainty Scale (IUS, Freeston et al., 1994) was developed by a team at Université Laval (Québec, Canada) in order to develop an understanding of worry and GAD. The original 27-item scale has been translated into several different languages, briefer versions have been developed (e.g., Carleton et al., 2007), and adapted for use with children and young people (see Shihata et al., 2016). Although the IUS has been the most widely used scale, other similar measures exist. In a study of three measures, Fergus (2013) found significant overlap, although each measure also accounted for unique variance in measures of distress.
In terms of key reviews, Carleton (2012) reviewed the changing definitions of IU up until that point, indicating perhaps that IU was a measure in search of a construct. Birrell et al. (2011) reviewed the different factor analytic studies up until that point and conclude there appear to be two factors consistently measured by the IUS, namely, prospective IU (also described as desire for predictability) and inhibitory IU (also known as behavioral paralysis). 
The replicated relationships of IU with other disorders have been subject to meta-analysis, namely for anxiety disorders and depression (McEvoy, Hyett et al., 2019), eating disorders (Brown et al., 2017), and anxiety and worry in young people (Osmanağaoğlu, 2018). Importantly, McEvoy, Hyett et al. (2019) also considered a range of moderators (e.g., age, gender, clinical status, etc.) and conclude that these generally do not affect these relationships to any great extent. Other reviews address IU in relation to neural and psychophysiological correlates (Tanovic et al., 2018) and threat extinction training (Morriss et al., 2021), while Rosser (2019) reviews research on IU and temporal precedence and causality. Carleton (2016) reviews models of uncertainty while Milne et al., (2019) review the relationship between threat and uncertainty in anxiety. Broader treatment implications are considered by Einstein (2014) and Jacoby (2020), while Wilson et al. (2023) review evidence for change in IU in psychosocial treatments for GAD. Finally, McEvoy, Carleton et al. (2019) consider an agenda for research into IU as a transdiagnostic construct in terms of the Research Domain Criteria (RDoC, Insel et al., 2010).
The IU construct is essentially defined by the initial measure and later variants and developments. Although the original focus was GAD, the interest then spread to other forms of anxiety and OCD, and then other mental health problems (e.g., depression, psychosis, eating disorders) and more recently to PTSD so it is clearly a transdiagnostic construct in mental health. It has also been increasingly implicated in neuro-divergency (ADHD and especially autism). Further, IU has been implicated in adaptation among informal carers, to physical health problems, as well as racism and discrimination, medical training, tourism, gun purchases, the H1N1 pandemic, climate change, etc. Thus, IU has increasingly been shown to have trans-situational relevance. Further, while the bulk of the research in the first 25-years was mostly in English-speaking and Northern and Western European countries (Sullivan et al., 2023), in the last few years, and especially during the pandemic, the construct has been increasingly researched in many parts of Asia, Eastern and Southern Europe, South America and Africa.
The aim of this review is to take a historical bibliometric perspective (Donthu et al., 2021) and systematically track the rise and spread of IU from a putative specific factor in one of several models of a single disorder, namely, GAD (Behar et al. 2009; Freeston, 2022) to a transdiagnostic, trans-situational and increasingly relevant construct in international and cross-cultural contexts