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From the University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
Address reprint requests to: Andrew Baum, University of Pittsburgh Cancer Institute, Department of Behavioral Medicine and Oncology, 3600 Forbes Ave., Suite 405, Pittsburgh, PA 15213. E:mail: baum{at}pcicirs.pci.pitt.edu
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMETHODRESULTSDISCUSSIONNOTESACKNOWLEDGMENTSREFERENCES |
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METHOD: Victims of three types of trauma, a motor vehicle accident (N = 115), a hurricane (N = 182), and recovery work after an airline disaster (N = 159), completed the ITQ along with the Impact of Event Scale (IES) and the Symptom Checklist-90, Revised (SCL-90-R), at several different time points after their exposure.
RESULTS: The ITQ was a reliable and valid instrument that was positively related to concurrent measures of distress as well as a predictor of long-term stress responding. Characteristics of intrusive thoughts reflecting the extent to which they were unwanted or controllable, were identified as key determinants of distress.
CONCLUSIONS: The ITQ is a useful adjunct to current measures of intrusions, allowing for greater specificity in analyses of responses to trauma. Evaluation of characteristics of intrusions indicated that frequency of intrusions was neither the only predictor of distress nor the best predictor of trauma-related outcomes.
Key Words: intrusive thoughts, • trauma, • stress, • assessment.
Abbreviations: ITQ = Intrusive Thoughts Questionnaire;; IES = Impact of Event Scale;; SCL-90-R = Symptom Checklist-90, Revised;; PTSD = posttraumatic stress disorder;; MVA = motor vehicle accident;; GSI = global severity index.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Intrusive thoughts are not a new construct; Freud suspected them as a cause of distress and they have been characterized in several psychodynamic systems (4, 5). They have received considerable empirical attention in the past 20 years, in part because persistent intrusions are an essential characteristic of PTSD (6). They are usually defined as unbidden, uncontrollable, and generally unwanted thoughts or images of a past event, an anticipated event, or of some other stimulus or situation (2). They are characteristic of several psychiatric disorders, but they do not occur exclusively as part of a disorder. Many people report intrusions after a traumatic event, but the majority of these individuals do not develop PTSD (7, 8). For most, intrusive thoughts gradually decrease to very low levels (3, 8).
Intrusive thoughts need not be negative or associated with a stressor; they may be neutral or positive and can occur in many benign situations (9). However, the uncontrollable or unpredictable nature of intrusive thoughts may be stressful. Intrusive recollections, images, and other representations of a stressor seem to contribute to the persistence of chronic stress (1). They also seem to be related to several stress-related biological outcomes, including resting blood pressure and adrenal activity (eg, Refs. 1, 10). They are ordinarily transient and often identifiable only after they have occurred, making them very difficult to measure. Their significance for stress, mental health, and overall well being suggests that innovative approaches to their investigation are warranted.
The most commonly used measure of intrusive thoughts is the IES (2). This 15-item instrument has good test-retest reliability and yields an overall score and values for subscales that address intrusions (Cronbach’s 
= .78) and avoidance (Cronbach’s = .82). The IES has been widely used in studies of community disasters and individual traumas (eg, tornados, floods, motor vehicle accidents, rape; Refs. 8, 11, 12). Most of the data we have about the experience and effects of intrusions has been derived from this instrument. The IES has also been studied extensively in conjunction with formal diagnoses of PTSD and has been used as a proxy for a diagnostic interview. A recent revision of the IES by Weiss and Marmar (13) includes seven symptoms of hyperarousal, another key feature of PTSD. Additionally, the response format has been changed in the new version from frequency of symptoms on a 0, 1, 3, or 5 scale to amount of distress on a 0 to 4 scale.
Although the IES has been extremely useful in illustrating the importance of intrusions, it does not provide much information about intrusive experiences. There are many facets to the experience of trauma-related intrusions. Information obtained on each of these characteristics should improve our ability to predict long-term outcomes after a trauma over that explained by a single dimension, such as frequency of intrusions as seen with the IES. One can identify at least six variable dimensions of intrusions that may contribute to overall distress: 1) the frequency of intrusive thoughts; 2) the predictability or occurrence of these thoughts in the presence or absence of cues; 3) whether intrusions are negative and/or upsetting; 4) the degree to which these thoughts are unwanted; 5) the extent to which intrusions are controllable once they occur; and 6) the extent to which they occur as dreams during sleep. Previous research has suggested that these characteristics of intrusive thoughts are related to stress and mental health outcomes (eg, A.B., unpublished data, 1998). The ITQ was developed to measure these characteristics of intrusive thoughts. The ITQ yields a composite score that reflects overall disturbance associated with intrusions that should be highly correlated with the IES-Intrusion score.
Items for the ITQ were selected and/or discarded over several years of developing a general item base for the inventory. Largely drawn from clinical experiences and research on disasters, the original pool of items was reduced after examination of item frequencies and correlations among items when subsets of the items were given to participants in several disaster studies. Once constituted, the ITQ was administered to participants of three ongoing studies of victims of three types of trauma: MVAs, a major hurricane, and rescue and recovery work after an air disaster. In two of these samples (the MVA victims and the airplane crash workers), the ITQ was administered four times over the course of the year after the event. It was expected that reports of intrusions would decrease with the passage of time. As part of these larger studies, several other measures were administered allowing comparison of the ITQ to scores on the IES (2) and the SCL-90-R (15). These comparisons allowed assessment of the convergent, discriminant, and predictive validity of the ITQ.
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METHOD |
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TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Motor Vehicle Accident Study.
Victims of MVAs (N = 115) were recruited from either a regional trauma center in a large middle Atlantic metropolitan area or local police reports of MVAs. Individuals were considered for study participation if they were admitted to the trauma center or another area emergency room or trauma unit. Experimenters contacted all potential participants after discharge from the hospital. Approximately 44% of all eligible candidates agreed to participate.
A control group of 42 participants was recruited from among emergency room patients at the same hospital as the MVA victims. All of these individuals presented with minor injuries (eg, broken leg, sprained wrist, lacerations). Otherwise comparable to the MVA sample, these participants were considered to have experienced a low-threat injury and could not have been in a MVA in the past 5 years. The final sample was 52% female with a mean age of 35 years (range, 18–64) and a median education of some advanced schooling. Racial composition reflected the racial make-up of the surrounding communities and consisted of participants who identified themselves as Caucasian (76%), African American (14%), Hispanic (6%), Asian American (1.5%), or from another race (3%). Participants were seen four times over the course of a year, 2 to 3 weeks after the accident, and then 3, 6, and 12 months afterward. About a third of the sample failed to complete all four assessments.
Hurricane Andrew Study.
Participants were recruited from Dade County in South Florida, which was devastated by Hurricane Andrew. The sampling areas included some of the most heavily affected areas of the county. Because of the magnitude of destruction associated with the storm (eg, homelessness/relocation, sustained phone and power interruptions, uninhabitable homes), it was difficult to locate potential subjects by phone or mail. Alternative methods of subject recruitment were used: flyers were handed out in shopping centers and neighborhoods, the research team went into affected neighborhoods knocking on doors, and affected staff at local universities and colleges were contacted regarding possible participation in the study; 183 subjects were recruited using these methods. However, one subject was excluded because she did not read well enough to complete the questionnaires. The final sample included 119 women and 63 men with an average age of 39 years (range, 18–80) and a median education level of some college or advanced training. Comparison with census data from 1990 suggested that the cultural diversity of the South Florida area was reflected in the sample: 44% of the sample was Caucasian, 34% was African American, 18% was Hispanic, and 4% was from other ethnic groups.
USAir Flight 427 Study.
On September 8, 1997, USAir Flight 427 crashed outside of Pittsburgh, Pennsylvania, exploding on impact and killing all 132 crew and passengers on board. The nature of the crash, the terrain, and working conditions made the recovery and cleanup effort very stressful. A total of 159 workers at the crash site and a control group of 41 occupation-matched participants who did not participate in the cleanup were recruited. Initial contacts were made through supervisors of medical, emergency response, and airport staff of units directly involved at the crash site. Unit members were then contacted individually. More than 90% of those approached agreed to participate. Participants answered questions at four times, 2, 6, 9, and 12 months after the crash. Approximately 65% of these participants were male, their average age was 36 years (range, 18–68), and most were white (93%) with some college or advanced education beyond high school.
Procedures
Motor Vehicle Accident Study.
Participants were seen in their homes by study researchers for each of the four assessments. During these sessions instructions were given for the completion of the questionnaires and a 15-hour urine sample. Additionally, blood pressure and heart rate readings were taken and a 5-minute proofreading task was given (15). Participants were thanked and compensated $20.00 for their time and cooperation.
Hurricane Andrew Study.
Participants were interviewed two times approximately 3 days apart 5 to 15 weeks after the hurricane hit the South Florida area. At the first visit, participants were interviewed about demographics and socioeconomic background, the respondent’s location and experiences during and after the hurricane, and damage, injury, and loss due to the disaster. A battery of questionnaires was left with the participant to be completed and returned, along with a 15-hour urine sample, at the second visit. Additionally, at the second visit, heart rate and blood pressure readings were taken and a blood sample was drawn. Participants were thanked and paid $60.00 for their participation (16).
USAir Flight 427 Study.
Participants were first seen 4 to 8 weeks after work at the crash site had ended at their place of work or at their volunteer station. Blood pressure and heart rate measures were obtained, a packet of questionnaires and a 15-hour urine sample were explained, and, for a subsample, a blood sample was drawn. Participants were compensated $25.00 for their participation at each time point (17).
Measures
Several questionnaires were administered in these three studies. Three of these questionnaires, the ITQ, the IES, and the SCL-90-R, were used in all three and were used in the present analyses.
Intrusive Thoughts Questionnaire.
The ITQ was used to assess the occurrence, frequency, and amount of distress associated with intrusive thoughts.1 Six dimensions of the experience of these thoughts are addressed, specifically the general occurrence of these thoughts, how much distress they cause, whether or not they are predictable, cued and/or controllable, unwanted, or they interrupt sleep. The ITQ consists of 13 items (Table 1) from which specific information regarding the experience of intrusions can be assessed or a total score can be computed.2 The response formats for the scalable items are bipolar scales on which the participant circles a number from 1 to 4 or 1 to 7. Higher numbers reflect more intrusions and disturbance. If the participant has not experienced a particular item, they are instructed to mark a score of zero for that item. Item responses are then summed to create a composite score.
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’s ranged from .85 to .89 for the intrusions scale and .81 to .87 for the avoidance scale) and test-retest reliability (reliability coefficients ranged from .42 to .79 for the intrusions scale and .45 to .77 for the avoidance scale) in the present samples.
General Distress.
General distress was assessed using the GSI from the SCL-90-R (14). Participants rated how much they have been distressed or bothered by each of 90 symptoms during the preceding week. Cronbach’s ’s ranged from .97 to .98 in the present samples indicating good internal consistency. These scores were then compared with the ITQ to establish its discriminant and predictive validity.
Data Analysis
Frequencies and means for each of the ITQ items as well as the total scores were examined. The internal consistency and test-retest reliability of the scale were examined as were the ITQ’s convergent, discriminant, and predictive validity. Validity was assessed using hierarchical multiple regression. In the MVA and crash samples, the effects of age, sex, and education were entered first in order to control for their effects on the target variable, then victim status, ITQ scores, and the group by ITQ score interaction were entered as separate steps. In the Hurricane Andrew sample, age, sex, and education were entered first, followed by the ITQ score. In the text and tables, ß is used to represent the standardized regression coefficients and the lower-case b is used to represent the unstandardized regression coefficients. The discriminant and predictive validities of the IES Intrusions scale were also examined. The best subset of ITQ items to use as a predictor of concurrent distress was determined by using backward regression analyses where age, education, and gender along with each ITQ item were entered as a block. Because of the small sample sizes in the MVA sample, only the crash and hurricane samples were used for these analyses. In the crash sample, the variable indicating whether or not the participant was at the crash site was also included. In the case of later reports of distress in the crash sample, ITQ items at Time 1 and distress at Time 1 were entered into the equations in order to predict distress at Times 2 to 4.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Internal Consistency, Means, and Variance of the ITQ
A total score was computed by summing each of the items. Cronbach’s ’s were then calculated for the ITQ in each of the data sets. In the MVA sample, the coefficients were .91, .93, .91, and .93 at 1, 3, 6, and 12 months after the accident, respectively. In the crash workers sample, the coefficients were .85, .84, .85, and .81 at 1 to 2, 6, 9, and 12 months after the accident, respectively. In the Hurricane Andrew sample, the coefficient was .90. These internal consistency values suggest that the scale is reliable across different types of trauma.
Means for the ITQ in the MVA sample were 17.09 (SD = 12.29), 11.75 (SD = 11.47), 11.32 (SD = 10.86), and 10.21 (SD = 11.01) at the four time points, respectively. Means in the crash sample were 10.49 (SD = 8.69), 7.91 (SD = 7.67), 6.59 (SD = 7.24), and 5.86 (SD = 6.28), respectively. The mean of the hurricane sample was 14.16 (SD = 14.05). Scores in all three samples were positively skewed. This is consistent with distributions of the item scores reported in Table 1 and what we have previously found with other measures of intrusions and distress after trauma. To correct for the skewness, square root transformations were performed on each of the values when conducting parametric statistics.
Group Differences
Differences across groups within the MVA and airplane crash samples provided initial estimates of validity (see Table 2). MVA victims reported more intrusive thoughts about their accidents than the control participants at 3, 6, and 12 months. Likewise, crash workers reported more intrusive thoughts than the control participants at 2, 9, and 12 months in the airplane crash sample.
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Changes Over Time and Test-Retest Reliabilities
It was expected that scores on the ITQ would decrease over the course of the 12-month collection period in the MVA and crash samples. Only 16 MVA study participants (12 victims and 4 controls) completed the form at all four time points. In this small sample, there were no overall significant differences over time, F(3,10) = 2.60, p = .11. In the crash sample, 124 participants (112 crash workers and 12 controls) completed the ITQ at every assessment. There was a significant group by time interaction for ITQ scores, F(3,118) = 2.74, p < .05. Scores for the crash workers declined significantly from the first to the second assessment, t(112) = 4.84, p < .001. There were no changes over time in the control group.
Test-retest reliability coefficients between Time 1 and the later three time points were .48, .52, and .56, respectively, in the MVA sample after controlling for the influence of sex, and .66, .68, and .64, respectively, in the crash sample. Test-retest reliabilities between Time 2 scores and scores at Times 3 and 4 were .78 and .73, respectively, in the MVA sample after controlling for sex, and .75 and .77, respectively, in the crash sample. The test-retest Reliabilities between Times 3 and 4 were .77 and .76 in the MVA (after controlling for sex) and crash samples, respectively. If one assumes that distress was greatest at Time 1 in both of these samples, that typical experience was distorted most at that time, and that recovery and reduction of intrusive experience occurs primarily between Time 1 and Time 2 (see Table 2), correlations between Time 1 scores and later scores should be lower than correlations of subsequent times with later scores.
Convergent and Discriminant Validity
Convergent validity was assessed by examining the relationship between scores on the ITQ and scores on the Intrusions scale of the IES. Scores on the ITQ shared 38% to 52% of the variability in IES-Intrusions at the four time points in the MVA study. Shared variances were 26% to 40% across the air disaster sample and 34% in the Hurricane Andrew sample, F values > 57.00, p values < .001. Although these two measures of event-related intrusions were positively associated with each other, less than half of their variance was shared, suggesting that the two scales measure different dimensions of intrusions.
To demonstrate discriminant validity, the ITQ should be moderately and positively associated with other measures of distress indicating that they are related but separate constructs. Scores on the IES-Avoidance scale as well as the GSI from the SCL-90-R were examined in all three samples. As shown in Tables 3 through 7, reports of intrusions on the ITQ were positively associated with concurrent scores on the IES-Avoidance scale (see Tables 3, 5, and 7) and the GSI (see Tables 4, 6, and 7) at each of the assessments in all three samples. Additionally, significant ITQ by victim status interactions were found for the IES-Avoidance score in the MVA data at the third assessment (see Table 3), and for the GSI score (see Table 4) in the crash sample at the third assessment. In the MVA sample, higher ITQ scores were associated with higher avoidance scores in both the victim group, b = .77, F(1,75) = 42.12, p < .001, and the control group, b = .32, F(1,75) = 5.37, p < .05. In the crash sample, ITQ and GSI scores were positively associated within the crash worker group, b = .12, F(1,147) = 57.60, p < .001, but were not associated in the control group, b = .04, F(1,147) = 1.52, p = .22.
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R2 = .01, F(1,153) = 10.71, p < .001. Post hoc analyses revealed the same pattern of results as found for the ITQ. Scores on the IES-Intrusions scale were positively associated with GSI scores in the crash worker group only, b = .12, F(1,153) = 43.99, p < .001. Finally, analyses addressed the extent to which the ITQ explained variance in distress above and beyond that explained by the IES-Intrusions scale. Multiple regression equations were repeated using the ITQ as a predictor of concurrent distress after controlling for the effects of IES-Intrusions. The variance in distress scores already accounted for by IES-Intrusions, victim status, and the demographic predictors was substantial (32%–47%), but the ITQ accounted for significant additional variance in several measures of distress. The ITQ explained an additional 2% of the variance in IES-Avoidance scores at Times 2 and 4 in the MVA sample, F(1,60) = 6.19, p < .05 and F(1,82) = 4.56, p < .05, respectively, and at Times 1 and 4 in the air disaster sample, F(1,151) = 6.09, p < .05 and F(1,130) = 3.81, p < .05, respectively. Likewise, the ITQ accounted for an additional 3% of the variance in GSI scores at the Times 2 and 3 in the MVA sample, F(1,58) = 4.29, p < .05, and F(1,70) = 4.74, p < .05, respectively, and an additional 7%, 2%, 8%, and 4%, respectively, at each of the four time points in the crash sample, F(1,160) = 18.43, p < .001, F(1,142) = 4.10, p < .05, F(1,143) = 18.48, p < .001, and F(1,133) = 7.60, p < .01, respectively. The ITQ did not account for any additional variance in either distress measure in the hurricane sample.
Predictive Validity
Because of the small number of participants who completed the ITQ at the first assessment in the MVA sample, predictive validity was assessed only in the crash workers sample. Scores on the ITQ at the first assessment were used to predict long-term stress responding and coping at the latter three time points in multiple regression analyses. Multiple regression equations were the same as those reported above except the outcome measures at the first assessment were entered first when predicting distress at a later time. Higher scores on the ITQ at the first time point predicted higher GSI scores at 9 and 12 months, ß = .13, R2 = .01, F(1,142) = 4.84, p < .05, and ß = .14, R2 = .01, F(1,134) = 4.41, p < .05, respectively, and higher IES-Avoidance scores at 12 months, ß = .21, R2 = .03, F(1,120) = 4.57, p < .05. When the predictive ability of the ITQ was reexamined after controlling for the effects of the IES-Intrusions scale, the above findings were unchanged. The predictive validity of the IES-Intrusions scale was also examined. Scores at the first assessment did not predict any of the outcome measures at the later assessments.
Contribution of Individual Items
The final analytic step was to consider the relationship of individual items, or intrusion characteristics, to distress in these samples. The composite score on the ITQ is different from the IES total score in that it reflects summed responses to items tapping the frequency, predictability, and controllability of intrusions as well as how unwanted and upsetting they are. Examination of item correlations with the IES-Avoidance and GSI outcome measures suggested that several of these characteristics were associated with outcomes over time in the MVA and crash samples and in the hurricane sample. To determine which of these characteristics made up the best subset of ITQ items for predicting distress outcomes, backward regression analyses were conducted in which age, education, and gender were entered with each ITQ item as a single block. Small sample sizes over time in the MVA study limited these analyses to the crash and hurricane samples. In the crash sample, worker status (at cleanup/control) was also entered as a predictor. For prediction of stress at Times 2 to 4 in the crash study, ITQ items and distress at Time 1 were entered as predictors.
Concurrent Analyses.
Analyses in the crash sample indicated that 18% to 33% of the variance in concurrent GSI scores was accounted for by five or fewer of the predictor variables at each of the four time points (see Table 8). Gender and controllability of intrusions were associated with GSI scores at each time point. The frequency of intrusions was also positively associated with concurrent distress at 2, 9, and 12 months. How disturbing or upsetting predictable intrusions were was positively associated with distress at 6 and 12 months after the crash, and more education predicted fewer intrusions at 2 and 12 months. The best subset of predictors also accounted for 30% to 43% of the variance in concurrent IES-Avoidance scores at the four time points (see Table 9). Controllability was again negatively related to avoidance at 2, 6, and 9 months, but gender and age only predicted the outcome at 2 months. Education was negatively associated with avoidance at 6, 9, and 12 months, and the degree to which intrusions were disturbing was positively associated with avoidance at 2, 6, and 12 months.
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Predictions Over Time.
Prediction of distress and avoidance in the crash sample at 6, 9, and 12 months with ITQ data from the 2-month time point accounted for more than half of the variance in GSI scores and 25% to 41% of the variance in IES-Avoidance scores at the latter time points (see Tables 10 and 11). Working at the crash site and higher GSI scores at 2 months predicted higher GSI scores at 6, 9, and 12 months (see Table 10). The frequency of unwanted intrusions at 2 months was positively associated with distress at 6 months, and less controllability of intrusions at 2 months predicted greater distress at 9 months. The IES-Avoidance score at 2 months was also positively associated with avoidance at each time point, and education was negatively associated with avoidance (see Table 11). The extent to which unwanted intrusions were disturbing was positively associated with avoidance at 6 and 12 months, and lower rates of controllability predicted more avoidance at 9 months.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONNOTESACKNOWLEDGMENTSREFERENCES |
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Data bearing on the psychometric properties of the ITQ provided ample evidence of its reliability and validity. The overall (composite) score was internally consistent and stable in all three samples. Cronbach’s ’s were consistent in all three, varying from 0.81 to 0.93, and changes over time in longitudinal studies was as predicted. Mean scores were highest among MVA victims and lowest among emergency workers experiencing secondary trauma, again suggesting valid assessment of major sequelae of traumatic stress. Test-retest reliability was low between the first and second assessments in the MVA and crash studies, but much higher when comparing responses over the last three time points. This was expected because participants in these studies were predicted to show decreases in intrusions in the first 3 to 6 months after experiencing a trauma. Once they had decreased (by 3 months in the MVA study and 6 months in the crash study), stability over time was much greater.
Evidence of discriminant validity was also observed, with the ITQ predicting avoidance and distress after removing variance associated with victim status and variables, such as age, gender, and education. Some effects of gender on reporting of intrusions were indirect but once the effects of gender were removed, the ITQ predicted substantial incremental variance in both the IES-Avoidance measure and the GSI from the SCL-90-R. In the crash sample, predictive validity was assessed by examining relationships between Time 1 ITQ scores and distress at the later time points. The overall score on the ITQ was positively associated with distress scores at 9 and 12 months and avoidance at 12 months. The IES did not predict later distress or avoidance.
Evaluation of the influences of various intrusion characteristics on outcomes such as distress produced several effects beyond direct relationships between frequency of intrusions and outcomes such as avoidance. Controllability of intrusions, indexed as how easy one can get rid of intrusions when they occur, was most consistently associated with avoidance and distress; when participants reported that intrusions were not controllable nor readily dispelled, they reported more distress and avoidance. Education was negatively associated with some outcomes although less consistently, and measures of frequency and distress caused by intrusions also predicted distress and avoidance. Finally, the extent to which intrusions were experienced as unwanted affected the scores on the GSI and IES-Avoidance measures. Predictability, or the presence of clear cues for intrusions, was not related to distress, and effects of controllability and unwanted dimensions were more strongly related to outcomes than were predictors derived from reports of frequency of intrusions or how much distress intrusions caused.
This last finding begins to unravel some of the more or less toxic components of intrusive experiences after trauma. Most people experience intrusive thoughts immediately after a stressful event, but most people show clear and rapid declines in this experience. Some people persist in having them, and those who do are more likely to exhibit mental health problems, chronic stress, PTSD, or other profound consequences of stress. By examining predictors of distress and avoidance in these different samples, the influences of some possible causes of persistent distress were evident.
There were some relationships between gender and intrusions measured with the ITQ, and education was related to distress. However, the scores on the ITQ were primarily affected by victim status and were not systematically related to age or other personal variables. These findings argue for the validity of the ITQ as a measure of intrusions, particularly when one seeks to identify antecedents of distress. The ability to measure individual characteristics of intrusions, in addition to a composite measure of frequency and discomfort, will allow greater specificity in analyses of response to traumatic stressors and should refine our ability to predict outcomes and identify vulnerability patterns for intervention and mitigation.
Clearly, the ITQ does not include all possible predictors of distress. It focuses more on the characteristics of the experience of intrusive thoughts than on aspects of people’s responses to them. It is possible that meta-cognition, counterfactual thinking, and other aspects of how people respond to unsettling intrusive thoughts or images could explain part of the variance not explained by the ITQ. Additional research and instrument development should address these and other unresolved issues. At present, the ITQ measures features of intrusive thoughts and how they are experienced, and provides a useful measure of these determinants of distress.
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ACKNOWLEDGMENTS |
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TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONNOTESACKNOWLEDGMENTSREFERENCES |
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NOTES |
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TOPABSTRACTINTRODUCTIONMETHODRESULTSDISCUSSIONNOTESACKNOWLEDGMENTSREFERENCES |
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In the Hurricane Andrew sample, questions 1 and 4, which asked participants to indicate how often (from once a week or less to several times a day) they thought about or remembered the disaster in the past week, were replaced by recall prompts asking for the actual number of times (with responses greater than 9 coded as 9). The results seemed to be unaffected by this different response format.
Received for publication March 9, 1998.
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