Introduction
Review Objectives
Method
Search
Study Selection
Information Sources
Eligibility Criteria
Studies Types
Experimental Manipulation Studies
Temporal Precedence Studies
Participants
Outcomes and Measures
Additional Exclusion Criteria
Data Collection Process
Data Items
Summary Measures
Risk of Bias: Quality Assessment
Results
Study Selection
Study Characteristics
Article, year, and location | Sample type | Relevant psychological difficulties (*diagnosed) | Sample size (n by group) | Mean age in years (SD) | % Femalea | Ethnicity (n) |
---|---|---|---|---|---|---|
Bomyea et al. (2015) USA | Clinical | Generalised anxiety disorder* | 28 | 34.4 (10.8) | 71.4 | White (22), Asian (3), Hispanic (1), Native American (1), Other or mixed race (1) |
Britton and Davey (2014) UK | General population | Anxiety-, obsessive–compulsive-, and mood-related | 61b (High IU n = 30; low IU n = 31) | 20.26 (2.82) | 73.8 | Not reported |
Deschenes et al. (2010) Canada | General population | Anxiety- and mood-related | 75c (High IU/negative beliefs about uncertainty n = 38; low IU/positive beliefs about uncertainty n = 37) | 28.69 (12.32) | 66.7 | Caucasian (53), African-American or Caribbean (7), Asian (7), Hispanic (1), Aboriginal (1), Multi-racial (4), Other ethnic origins (2) |
Faleer et al. (2017) USA | General population | Obsessive–compulsive-, anxiety-, and mood-related | ||||
Study 1 | 60 (High IU n = 30; low IU n = 30) | 20.4 (3.4) | 68.4d | Caucasian (37), African American (14) Asian (4), Bi-racial (3), Hispanic (2), and Other (1) | ||
Study 2 | 83 (High IU n = 37; low IU n = 46) | 19.7 (3.0) | 58 | Caucasian (45), African American (23), Asian (6), Bi-racial (3), Other (5), and did not report (1) Additionally: 12.0% also identified as Hispanic or Latinoe | ||
Study 3 | 95 (High IU n = 51; low IU n = 44) | 19.3 (1.8) | 61.1 | Caucasian (44) Black/African American (30), Asian American (5), Native American (1) Multi-racial (5), Other (7), and did not report (3) Additionally: 15.8% also identified as Hispanic or Latinoe | ||
Goldman et al. (2007) Canada | General population | Anxiety- and mood-related | 30 (Intervention n = 15; control n = 15) | 26.0 (10.2) | 66.7 (Same male:female ratio in both groups) | European White (16), Asian or Asian American (8), Middle Eastern (3), Hispanic (1), East Indian (1), and biracial (1) |
Hedman et al. (2013) Sweden | Clinical | Severe health anxiety/hypochrondriasis* | 81 (Intervention n = 40; control n = 41) | Intervention: 39.3 (9.8) Control: 38.8 (9.5) | 74.1 (Intervention: 70.0; control: 78.1) | Not reported |
Ladouceur et al. (2000) Canada | General population | Anxiety-relatedf | 42 (High IU n = 21; low IU n = 21) | Females: 23.8 (7.07) Males: 21.7 (1.92) | 71.4 | Not reported |
Meeten et al. (2012) UK | General population | Anxiety- and mood-related | 46 (High IU n = 25; low IU n = 21) | 26.8 (5.52) | 71.7 | Not reported |
Mosca et al. (2016) Italy | General population | Anxiety- and mood-related | ||||
Study 1 | 43g (High IU n = 22; low IU n = 21) | Not reported | 68 | Not reported | ||
Study 2 | 169h (High IU n = 59; low IU n = 58; control n = 52) | 24.83 (4.74) | 82.8 | Not reported | ||
Rosen and Knäuper (2009) Canada | General population | Anxiety-related | 153 (High IU/high SU n = 30; high IU/low SU n = 29; low IU/high SU n = 53; low IU/low SU n = 41) | Females: 20.80 (2.11) Males: 23.61 (8.28) | 81.7 | Not reported |
Su et al. (2016) USA | Clinical | Obsessive–compulsive disorder* | 70i | 32.6 (11.0) | 49 | Non-Hispanic white (66) |
Wilhelm et al. (2015) USA | Clinical | Obsessive–compulsive disorder* | 36 | 32.7 (10.5) | 47.2 | Caucasian (34), Asian (1), Hispanic (1) |
Study Designs
Manipulations
Temporal Precedence
Assessment Methods and Outcomes
Intolerance of Uncertainty: Mechanism Measures
Symptoms of Psychological Difficulties: Outcome Measures
Risk of Bias Within Studies: Quality Assessment
Selection Bias
Performance and Detection Bias
Attrition Bias
Reporting Bias
Results of Individual Studies
Study Outcomes Within Individual Studies
Article | Manipulation details | Outcome symptom and measure(s) | Analytic approach | Outcome summarya | Compared to low IUb | |
---|---|---|---|---|---|---|
Anxiety > in high IU | NA > in high IU | |||||
Britton and Davey (2014) Study 3 only | Vignette outlining either: (a) person encountering difficulties due to lack of response to uncertainty (High IU group); or (b) person encountering difficulties due to intolerance of uncertainty (Low IU group) For both high/low groups, participants required to provide advice to the person in the vignette | Inflated responsibility • Responsibility Attitude Scale (Salkovskis et al. 2000) • 4 Items used only Anxiety and mood • Visual Analogue Scale • 3 Individual items assessing sadness, negativity, and anxiety • Composite score of items also calculated | Independent t tests of high/low IU group difference | Inflated responsibility: High IU ≃ low IU Sadness and negativity: High IU ≃ low IU Anxiety: High IU > low IU Negative mood (composite score): High IU > low IU | ✓ | ~ |
Deschenes et al. (2010) | Two manipulations groups presented lecture on problem-solving and uncertainty, with uncertainty presented as having either: (a) a positive impact (positive belief about uncertainty/low IU group); or (b) a negative impact (negative beliefs about uncertainty/high IU group) on problem-solving | Anxiety and mood • Visual Analogue Scale • 4 Single items assessing anxiety, sadness, fatigue, and irritability Interpretation bias • Only ambiguous scenarios included Catastrophising/worry • Catastrophising Interview (Vasey and Borkovec 1992) | 2 × 2 ANOVA of group high/low IU differences pre-to-post manipulation ANCOVA of high/low IU group differences in bias and catastrophising (covariate: change in irritability) | Irritability: High IU < low IU pre-to-post manipulation Anxiety, sadness, and fatigue: High IU ≃ low IU pre-to-post manipulation Interpretation bias: (a. Worry about ambiguous scenario, b. perceived likelihood of pos/neg. outcome, and c. perceived badness of neg. scenarios) High IU ≃ low IU (Perceived positivity of positive scenario outcomes) High IU > low IU Catastrophising: (Steps and final step severity) High IU ≃ low IU (Perceived likelihood of steps occurring) High IU < low IU | X | X (Except irritability) |
Faleer et al. (2017) Study 1 | Replication of Rosen and Knäuper (2009) manipulation | Catastrophising/worry • Catastrophising Interview (Davey 2006) Affect • Positive and Negative Affect Schedule—negative affect only (Watson et al. 1988) Perceived threat of intrusive thoughts • Single item; 5-point scale (Clark, Purdon, and Byers, 2000) | ANOVA of high/low IU group differences ANCOVA also conducted (covariates: baseline IU, worryc, and sex) | Catastrophising (number of steps): High IU > low IU Negative affect: High IU > low IU Perceived threat of intrusive thoughts: High IU > low IU All results held when covariates included in analyses | ✓ | ✓ |
Study 2 | Replication of Rosen and Knäuper (2009) manipulation | Affect • Positive and Negative Affect Schedule—negative affect only (Watson et al. 1988) Checking behaviour • Checking text for spelling/grammar errors (MacDonald and Davey, 2005) | ANCOVA of high/low IU group differences (covariate: baseline IU) | Negative affect: High IU ≃ low IU Checking behaviour (number of checks and time spent checking): High IU ≃ low IU | X (OCD related) | X |
Study 3 | Replication of Rosen and Knäuper (2009) manipulation | Threat estimation Checking behaviour • Matching to sample task (Rotge et al. 2008) | ANCOVA of high/low IU group differences (covariate: baseline IU) | Threat estimation: High IU ≃ low IU Checking behaviour (number of checks made, time spent checking, and accuracy of checking): High IU ≃ low IU | X (OCD related) | – |
Ladouceur et al. (2000) | Roulette gambling task with rigged loss outcome Participants instructed that win would result in donation to a fictitious foundation. Additional information emphasising that the chance of winning as low (high IU group) or high and minimising the consequence of losing (low IU group) | Worry • 3 Items used only; adapted to be relevant to manipulation task | Independent t tests of high/low IU group differences | Worry: High IU > low IU | ✓ | – |
Meeten et al. (2012) | Based on manipulation by Kelly (2009) Vignette describing a character in an uncertain situation with potential negative outcome. The character (which is sex-congruent with participant) has either high or low IU Participants instructed to consider a situation in their own life with similar unknown outcome, then write a diary entry (and re-read) about that situation as if they are the character from the vignette | Anxiety and mood • Visual Analogue Scale 4 Items assessing happiness, sadness, anxiety, and arousal • Change only assessed for sadness and anxiety Catastrophising/worry | 2 × 3 mixed ANOVA of high/low IU group differences pre-to-post manipulation (t2 & t3) (anxiety and mood only) Independent t test of high/low IU group differences | Sadness: High IU > low IU group irrespective of time High IU > low IU pre-to-post manipulation (between t1 and t2, maintained at t3) High IU > low IU (at t2 and 3, respectively) Anxiety: High IU ≃ low IU pre-to-post manipulation High IU > low IU group anxiety (at t2 only) Happiness and arousal: High IU ≃ low IU Catastrophising: High IU > low IU group | ~ | ✓ |
Mosca et al. (2016) Study 1 | Replicated manipulation by Grenier and Ladouceur (2004) adapted to use personally relevant life events A Vertical Arrow Technique (VAT) of idiographic negative life event was conducted in the morning. In the afternoon, participants were instructed to recall the event and read aloud a series of statements designed to induce either high or low IU, dependent on group | Worry • Worry and Intolerance of Uncertainty Questionnaire: Worry subscale (Grenier and Ladouceur 2004) Affect • Positive and Negative Affect Schedule (Watson et al. 1988) | ANCOVAd of high/low IU/control group difference (covariate: pre-manipulation scores) Mediation analysis (controlling for pre-manipulation scores) Reverse models also conducted | Worry: High IU ≃ low IU Positive affect: High IU ≃ low IU Negative affect: High IU > low IU Worry and negative affect (mediation): IU fully mediated experimental manipulation → worry; partially mediated experimental manipulation → NA Reverse models demonstrated significant partial mediations | X | ✓ |
Study 2 | As above, with following modifications: (1) 7–14 days between VAT and statements (M = 9.98, SD = 2.15 days), (2) re-reading of VAT prior to high/low IU statements, and (3) statements read, but not aloud Control condition: participants read neutral statements | Worry • Worry and Intolerance of Uncertainty Questionnaire: Worry subscale (Grenier and Ladouceur 2004) Affect • Visual Analogue scale • 4 Adjectives: happy and calm (composite used as positive affect); sad and anxious (composite used as negative affect) | ANCOVAd of high/low IU group differences (covariate: pre-manipulation scores and interval between VAT and statements) Mediation analysis using confirmatory path analysis Reverse models also conducted | Worry: High IU > low IU Low IU ≃ control Negative affect: High IU > low IU Low IU ≃ control Positive affect: High IU ≃ low IU ≃ control Worry, negative affect, and positive affect (mediation): IU mediator model manipulation group → symptom level reportedly better fit than reverse models | ✓ | ✓ |
Rosen and Knäuper (2009) | Based on linguistic manipulation by Salancik and Conway (1975) High and low IU manipulation groups presented with IU questionnaire items combined with qualifiers designed to increase (high IU) or decrease (low IU group) likelihood of endorsement. Standardised feedback to questionnaire performance in relation to IU was then presented to reinforce high/low IU groups Situational Uncertainty (SU) also manipulated at two levels (low/high) | Worry and anxiety 1. Penn State Worry Questionnaire (PSWQ; Meyer et al. 1990) 2. State-Trait Anxiety Scale (STAI; Spielberger 1983) 3. 1 Likert-scale item assessing worry due to uncertainty relating to fictitious health condition used in manipulation task | ANCOVA of high/low IU group differences (covariates: STAI (state and trait) and PSWQ baseline scores) 2 × 2 ANCOVA of high/low IU × high/low SU group differences (covariates: baseline IU, STAI, PSWQ, and motivation to reduce uncertainty) for worry single item | Worry and anxiety: (All measures, except worry single item) High IU ≃ low IU Worry single item: IU*SU interaction = high IU/high SU > low IU/low SU | X | – |
Article | Intervention details | Outcome symptoms and measure(s) | Analysis | Outcome summarya | Temporal precedenceb | ||
---|---|---|---|---|---|---|---|
Analytic approach | Lag durationc | IU → symptom | Symptom → IU | ||||
Bomyea et al. (2015) | Cognitive behavioural therapy Ten one hour sessions over 10–12 weeks Computer assisted individual sessions with therapist Based on Coordinated Anxiety Learning and Management program (CALM; Craske et al. 2009) | Worry • Abbreviated Penn State Worry Questionnaire (Hopko et al. 2003) | Mediation analysis (predictor = time; mediator at t; outcome at t + 1) Reverse model switching mediator and outcome also conducted | 2 Weeks | Worry: Decrease in IU mediated subsequent decrease in worry across time Reverse model: Non-significant | ✓ | X |
Goldman et al. (2007) | Written exposure Five 30 min writing sessions Experimental participants: wrote a scenario of their worst fear including details of their emotion and experience; increasing description depth across sessions Control participants: wrote about a hypothetical non-emotional event | Worry • Penn State Worry Questionnaire (Meyer et al. 1990) • Adapted for weekly assessment consistent with Stöber and Bittencourt (1998); but retained 5 point rating Generalised anxiety disorder somatic symptoms • Worry and Anxiety Questionnaire (Dugas et al. 2001) • Adapted for weekly assessment Depression • Center for Epidemiological Studies Depression Scale (Radloff 1977) | Hierarchical linear modelling (Predictor at t predicting outcome variable at t + 1; controlling predictor at t + 1) Reverse model switching predictor and outcome also conducted | 1 Week approx.d |
Intervention group results
Worry, GAD, and depression IU → subsequent worry, GAD somatic symptoms, and depression Reverse models: non-significant
Control group results
Worry, GAD, and depression IU did not predict worry, GAD somatic symptoms, or depression Reverse models: worry and depression → subsequent IU | ~ | ~ |
Hedman et al. (2013) | Internet-based cognitive behavioural therapy 12 Weekly modules (module duration not specified) Therapist involved in intervention without face-to-face contact Mindfulness training included with CBT components | Health anxiety • Short version of the Health Anxiety Inventory (Salkovskis et al. 2002) • Composite of “Disease Conviction” and “Fear and Worry about Illness” subscales used as outcome variable | Mixed effects model (Predictor at t − 1; outcome at t, controlling for outcome at t − 1) Reverse model switching predictor and outcome variable also conducted | 1 Week | Health anxiety IU → subsequent health anxiety Reverse model: health anxiety → subsequent IU | ✓ | ✓ |
Su et al. (2016) | Exposure and response prevention Based on Kozak and Foa (1997) manual Seventeen 90 min sessions face-to-face with therapist; twice weekly over 8 weeks Followed by 16 week maintenance phase: receiving additional full intervention sessions and/or 45 min maintenance sessions | Obsessions and compulsions | Mediation analysis (Predictor = time; mediator at t; outcome at t + 1, controlling for outcome and depressiond at t) Reverse model switching mediator and outcome also conducted | During intervention: 4 Weeks Maintenance phase: • 4 Weeks • 12 Weeks | Obsessions and compulsions: IU did not significantly mediate subsequent obsessions and compulsions Reverse model: non-significant | X | X |
Wilhelm et al. (2015) | Cognitive therapy | Obsessions and compulsions • Yale-Brown Obsessive Compulsive Scale (Goodman et al. 1989a) | Random effects regression model (lagged time-varying change in covariate (t − 2 to t − 1) predicting outcome variable at t); median split employed on predictor (above vs. at/below median IU reduction) | 4–8 Weeks | Obsessions and compulsions: Compared to at/below median decrease in IU, above median decrease in IU → subsequent decrease in obsessions and compulsions | ✓ | – |