Preprint of paper on PROPS/CROPSPreprint of paper on PROPS/CROPSRicky Greenwald, Trumansburg, NY
Allen Rubin, University of Texas at Austin
Author Note
Ricky Greenwald, Trumansburg, NY; Allen Rubin, School of Social Work. The data on these measures were collected while the first author (RG) was at Community Services Institute, Springfield, MA.
We wish to thank Cathy King Pike, University of South Carolina, and Kenneth E. Fletcher, University of Massachusetts (Worcester) Medical School, for their suggestions, Kelly Moore, University of Texas at Austin, for her assistance, and Frank C. Sacco and Geraldine Wright, Community Services Institute, for their assistance and support.
Correspondence concerning this article should be addressed to Ricky Greenwald, Psy.D.,
483 Belknap Rd, Framingham, MA 01701. Electronic mail may be sent via Internet to
rickygr@childtrauma.com.
We report on the development and initial validation of two brief measures of children's post-traumatic symptoms: a child self-report and a parent report. Intended applications include post-disaster screening, tracking children's recovery in research and clinical settings, and screening for
post-traumatic stress among children with various presenting problems. A sample of 206 urban and
rural school children, grades 3-8, and their parents, completed these measures as well as a checklist
of the child's trauma/loss history. Findings provide preliminary support for the internal consistency,
test-retest reliability, content validity, and criterion validity of each measure. We recommend
cautious use of the measures, and suggest additional avenues of study.
Brief assessment of children's post-traumatic symptoms:
Development and preliminary validation of parent and child scales.
Child trauma is increasingly recognized as both widespread (Pynoos, 1990) and detrimental to psychosocial development and quality of life (Terr, 1991). Children exposed to extreme distress, such as occurs in natural disaster or violent incidents, will probably be traumatized (Terr, 1991), and they often have difficulty recovering unless special assistance is provided (Sugar, 1989). Such assistance first of all depends upon identification of those in need. However, reliable identification of traumatized children has typically been cumbersome, involving extended clinical interviewing (McNally, 1991).
A simple, effective screening instrument could facilitate the identification of children in need of special assistance following a natural disaster or other critical incident, and could have broader clinical and research applications. For example, such an instrument might also be useful to screen for post-traumatic stress in children with a variety of potentially related problems, even when a trauma has not been identified, so that treatment can be appropriately informed. And if such a measure were sensitive to changes in post-traumatic stress status, it could be used to track patterns of recovery, in both community and clinical settings. This type of measure would also be useful in testing some of the new trauma-focused treatments such as eye movement desensitization and reprocessing.
Some currently available measures are useful and psychometrically sound, but also have a variety of limitations. For example, the Impact of Events Scale (IES; Horowitz, Wilner, & Alvarez, 1979) is widely used with adults following a critical incident, and 8 of the items have survived norming with children (Dyregrov & Yule, 1995). However, children exhibit a much broader spectrum of post-traumatic symptoms than those covered in the IES (Fletcher, 1993; Terr, 1991). The IES is also limited in that an identified trauma is required as a reference point for all questions. However, a precipitating or predisposing event is not always recognized a priori as the source of a child's problems. Children often exhibit symptoms which may be trauma-based, but which mimic other conditions, including somatic disturbances, Attention Deficit Hyperactive Disorder, learning problems, anxiety, depression, oppositional behaviors, and conduct disorders (Green, 1983; Terr, 1991).
The Trauma Symptom Checklist for Children (TSCC; Briere, 1996) is a bit lengthy, containing 54 items, and fails to address some important aspects of child trauma symptomatology, such as somatic complaints and pessimistic future. Furthermore, over a third of the items - 10 on sexual concerns and another 10 on dissociation - focus on symptoms of sexual abuse and on chronic (versus critical incident) trauma, respectively. The Los Angeles Symptom Checklist (LASC; Foy, King, King, & Resnick, 1995) is not quite as long with 43 items, and is fairly comprehensive, but has only been normed downwards to adolescents. The adult-oriented content would make further downward extension inappropriate. The Children's Impact of Traumatic Events Scale (CITES; Wolfe, Gentile, Michienzi, Sas, & Wolfe, 1991) is shorter, with only 20 items, but fails to address many types of child trauma symptoms. Furthermore, the brevity of the CITES is deceptive, since it is derived from a much longer, copyrighted instrument (Child Behavior Checklist; Achenbach & Edelbrock, 1984) and cannot be used independently (T. Achenbach, personal communication, 11/93).
The intent here was to develop and validate a quick, convenient and effective instrument to screen for children's post-traumatic symptoms, with or without an identified trauma, which could also measure changes in symptomatology over time. We used a rather broad definition of post-traumatic symptomatology, reflecting the empirical findings (Fletcher, 1993; Terr, 1991) rather than being limited by the narrower Post-Traumatic Stress Disorder (PTSD) diagnosis. We also used a broad definition of trauma itself, to include major loss experiences. This, too, reflects the empirical findings (Newcorn & Strain, 1992), which indicate that children's reactions to a major loss can be very similar to their post-traumatic reactions, except that the hyperarousal effect may be absent. This inclusive, data-based definition of child trauma is arguably the most clinically relevant, since an awareness of a traumatic basis for a child's problem may influence the treatment plan, regardless of the specific diagnosis.
We actually developed two measures, the Child Report of Post-traumatic Symptoms (CROPS; modified from the TRICQ; Greenwald, 1996b) and the Parent Report of Post-traumatic Symptoms (PROPS; modified from Greenwald, 1996a). The dual source approach is essential in this area because of the quality and type of information available from each source. Children are good at reporting on their internal states, but tend to be poor observers of their own behavior. Parents, on the other hand, tend to underestimate their child's internal distress, but they are fairly good observers of the child's behavior (e.g., Loeber, Green, & Lahey, 1990). The CROPS and PROPS have some overlap of content, and are intended to be used either singly or in combination. They are both paper-and-pencil measures, but can also be administered orally, in person or by telephone.
Early Development
The CROPS was developed on the basis of symptoms most prominent in a recent meta-analysis of the child trauma literature (Fletcher, 1993), as well as those described as characteristic of PTSD in the DSM-IV (APA, 1994). The child is asked to rate the personal validity of various symptom-endorsing statements, covering the past 7 days, on a 0-2 scale in which 0 = "none," 1 = "some," and 2 = "lots." The original items were evaluated by a team of 5 academic and clinical experts in child trauma, for content validity as well as clarity. The measure was then piloted on 30 children in treatment, to test for comprehension as well as sensitivity to change. Almost half of the items were discarded for a variety of reasons, and others were modified. The 28 retained items each appeared to represent an element of post-traumatic reaction, be clearly understood by child responders, and change along with the child's post-traumatic stress status.
The PROPS has a somewhat different history. The CITES (Wolfe et al, 1991) items and CBCL (Achenbach & Edelbrock, 1984) format served as a model, which was then substantially modified and updated to reflect the DSM-IV as well as the empirical literature, as above. The parent is asked to rate the prevalence of various symptoms over the previous 7 days, on a similar 0-2 scale. These items were evaluated more informally by colleagues, and then piloted on the parents of 20 children in treatment. A number of items were dropped and several others were modified. The 30 retained items each appeared to represent an element of post-traumatic reaction, be clearly understood by the adult responders, and change along with the child's post-traumatic stress status.
Validation Studies
Since post-traumatic symptoms may be found in children following trauma, regardless of diagnostic status, we used a community sample to obtain a wide range in participants' history of exposure to traumatic experiences. The CROPS and PROPS were administered to a total of 206 students, and their parents, in grades 4-5 and 6-8, respectively, in two urban schools, and grades 3-6 in each of two rural schools. Participation was voluntary, with a pizza party offered in each school as an incentive to the class with the most completed packets. Participation was anonymous in the urban schools, and the response rate was 20% for a total of 152 usable protocols. The rural sample response rate was about the same (23%) for a total of 54 usable protocols.
In the rural schools, names were requested on the consent form. Some rural participants (N=30) also provided phone numbers as an indication of their willingness to be contacted. The CROPS and PROPS were readministered to this sample by telephone, 4-6 weeks after the initial paper-and-pencil administration.
Each participating student also filled out the Lifetime Incidence of Traumatic Events (LITE) checklist devised for this study, indicating which types of traumas or losses s/he had experienced, at what age, how many times, and how bad s/he felt at that time. Items included car accident, house fire, death of a family member, exposure to threats, sexual assault, witness to violence, and many other potentially upsetting events. Each participant's parent was given a similar form to report on the child's history. The child and parent were instructed to complete their own forms independently. Parents also reported the child's age, grade, ethnicity, and the parent's educational level. Neither the LITE nor the demographic items were repeated with the re-test sample.
Although there were hardly any minorities in the rural sample, the large majority (83%) of participating students were of minority ethnicity. Of the 88 percent who indicated ethnic status, most (53%) were African-Americans, followed by Hispanic (23%), white (17%) and other (7%). The median age of the participating students was 11.5, with a range from 8 to 15. Forty-nine percent were male, and 51 percent were female. Of the 77 percent of parents who indicated educational status, 17 percent did not graduate from high school, and 54 percent went no further than high school. Only 17 percent graduated from college, and 38 percent attended college or a trade school but did not attain a college degree.
Since the LITE covers such a wide range of type, frequency, and severity of trauma and loss experiences, it is really a screener, not an objectively scorable instrument. However, we needed a trauma/loss exposure score to correlate with the symptom measures. Therefore, the first author rated each participant's exposure severity on a scale of 1-4, with a higher number representing an estimate of greater exposure. The single rating was based on clinical judgment, taking into account both the parent and student LITE forms, including all responses, omitted items, and discrepancies. Blindness was maintained by reviewing the LITE forms, and providing the ratings, before looking at the CROPS and PROPS scores. Consistency in rating tendency was maintained by going through the entire stack of protocols three times, all within the same week, and occasionally revising a rating as appropriate.
Nine percent of the students were rated on the LITE as having no significant trauma or loss (a LITE score of 1). Forty-one percent received a LITE rating of 2, signifying the possibility of some significant trauma or loss. Thirty-two percent received a LITE rating of 3, signifying that significant trauma or loss was likely to have occurred. Seventeen percent received a LITE rating of 4, signifying that significant trauma or loss definitely occurred.
The first step in assessing the empirical characteristics of the parent and child measures was to examine the frequency distribution of responses to each item and the item-total correlations of each item. Each item was scored from zero to two, with a larger score representing a greater presence of the symptom. Items were deemed problematic if they had very little variation across response categories, if they did not correlate with total scale scores, and/or if their deletion resulted in an increase in coefficient alpha.
On the PROPS, no problematic items were found. As shown in Table 1, all 30 item-total correlations were significant at the .001 level, and ranged from .43 to .65. Coefficient alpha for the PROPS was very high, at .93. Three problematic items were identified on the 28-item CROPS, one about bed wetting and two about a pessimistic sense of the future. Before deleting those three items, coefficient alpha for the CROPS was .89. After deleting them, alpha increased to .91. Each of the remaining 25 item-total correlations on the CROPS was significant at the .001 level, and ranged from .36 to .66, as shown in Table 2.
The test-retest reliability of each measure was also high. For the total scores on the PROPS, the test-retest correlation was .79 (p<.001). For the total scores on the CROPS, the test-retest correlation was .80 (p<.001).
The criterion validity of each form was assessed by correlating total scores and individual item scores with the estimated level of exposure to trauma and loss experiences, represented by the LITE ratings described above. The correlation between the total scores on the PROPS and the LITE ratings was .56 (p<.001). For the CROPS, the correlation was .60 (p<.001). This supports the criterion validity of each measure, in that children who (in the clinician's judgment) had worse trauma and loss experiences also exhibited more trauma symptoms according to parents (on the PROPS) and according to the children themselves (on the CROPS). The correlations between the clinician's rating and each individual item on both measures are shown in Tables I and 2. The range of these correlations was from .26 to .45 on the PROPS, and from .19 to .52 on the CROPS.
The correlations between the total scores on each measure and the clinician ratings based on the LITE remained strong after controlling for age, gender, ethnicity, parent education level, and location (urban vs. rural). This was determined in a hierarchical multiple regression analysis in which the LITE rating was entered last, after entering the other five variables. Before entering the LITE rating, the multiple r was .325 for the PROPS and .226 for the CROPS. After entering the LITE rating, the multiple r's increased to .553 and .602, respectively. The criterion validity variable (i.e., the LITE rating) accounted for 20 percent of the variation in PROPS scores (r2 increased from .11 to .31) and for 31 percent of the variation in CROPS scores (r2 increased from .05 to .36) beyond the contribution of the other five variables.
In bivariate analyses, four of the five other variables (all except gender) were significantly related to PROPS scores. The correlation between age and PROPS scores was modest, at .26 (p<.001). Parent education level had a weak correlation with PROPS scores (r= -.19; p<.01). Ethnicity had a modest association with PROPS scores (eta= .24; p<.05). Hispanics had the highest mean score (23.3), followed by African-Americans (19.1), "Other" (18.4), Whites (16.8) and Asian-Americans (14.2). Location (urban vs. rural) had a weak association with PROPS scores (eta=.19), and the higher mean in urban areas (20.0 versus 15.1 in rural areas) appears to be explained by the higher proportion of ethnic minority group members in urban areas. In a two-way ANOVA, ethnicity remained significantly associated with PROPS scores (p<.05), but location did not. In a multiple regression analysis (entering all five variables simultaneously), however, only age remained significantly associated with PROPS scores (p<.05).
Looking at CROPS scores, only age (r=.16; p<.05) and parent education level (r= -.13; p<.05) had significant correlations. Both correlations were weak. And when all five variables were entered simultaneously in a multiple regression analysis, none remained significantly associated with CROPS scores.
An exploratory principal components factor analysis provided preliminary data on the factor structure of each scale. An oblique rotation was selected, since we expected that if the scale were found to be multidimensional, the factors would be highly correlated. That is, the scale was designed to assess one overarching construct, post-traumatic symptoms in children, with the understanding that at a lower order of abstraction discrete, but correlated, groupings of post-traumatic symptoms might be identified. The Kaiser-Meyer-Olkin Measure of Sampling Adequacy (KMO) and Bartlett Test of Sphericity both indicated that factor analysis is appropriate for the PROPS and CROPS data. The KMO was .90 for the PROPS and .75 for the CROPS. The Bartlett test for both was highly significant (p<.00001).
The initial output of the factor analysis pointed to specifying a three-factor solution for both the PROPS and the CROPS. On each, the scree plot leveled off with the third factor, and all of the remaining factors accounted for less than five percent of the variance. Tables 1 and 2 contain the rotated factor structure of the two scales.
The first factor on the PROPS contains mainly internalizing symptoms such as anxiety, fear, withdrawal, and depression. The second factor on the PROPS contains mainly externalizing symptoms such as conflictual interactions with others, anti-social behaviors, interpersonal difficulties, and overt irritability. However, the items do not fall cleanly into categories; for example, factor 1 includes "spaces out" and "nervous" whereas factor 2 includes "difficulty concentrating" and "hyper-alert." The third PROPS factor is composed primarily of somatic symptoms and sleep problems.
On the CROPS, the items loading on the first factor cover a wide range, including the sense of self as damaged, self-alienation, guilt, and dysphoria. The items loading on the second factor deal with somatic symptoms, thus paralleling somewhat the third factor on the PROPS. The items loading on the third factor of the CROPS deal primarily with avoidance and intrusive thoughts.
As expected, the factors identified within each scale were highly correlated. The factor correlation matrices are displayed in Table 3. A second-order factor analysis was then conducted, which confirmed our expectation that the factors of each scale could be conceptualized within the single overarching construct of post-traumatic symptoms in children. Again we used a principal components factor analysis with an oblique rotation. The variables in the second-order factor analysis were the three factor scores. The results indicated only one factor on each scale. On the PROPS, for example, the eigenvalue of the first factor was 2.23, and this factor accounted for 74.2 percent of the variance. The next eigenvalue was well below 1.0, at .48. The eigenvalues on the CROPS were 1.73 for the first factor (which accounted for 58.0 percent of the variance) and .69 for the second factor.
To explore the relationship between the two measures, we ran a factor analysis for all PROPS & CROPS items together. This yielded a two factor solution, or possibly a three factor solution. For the 2 factor solution, all the PROPS items loaded on one factor, and all the CROPS items loaded on the other. For the 3 factor solution, all the CROPS items loaded on one factor, and the other two factors consisted of the PROPS externalizing items on one factor and the remaining PROPS items on the other. This seems to suggest that different viewpoints are indeed being assessed by the two scales, supporting the value of using both without risk of redundancy. Of course, the measures are correlated (r=.60).
In light of the foregoing support for the reliability and validity of the scales, the final step in the analysis was to develop preliminary cutoffs to guide users in cautiously interpreting the scores. On the PROPS, the range for the entire sample was 0-55 (0-60 possible), the mean was 18.3, the standard deviation was 11.7 and the standard error of measurement was .81. The corresponding figures for the CROPS were 2-48 (0-52 possible), 19.7, 10.4 and .73. Both distributions contained some skewness (.71 for the PROPS and .49 for the CROPS), with some extremely high scores pulling the means above the medians (which were 16.9 for the PROPS and 18.6 for the CROPS).
For subjects with the highest LITE rating (i.e., a rating of 4, the highest estimated level of trauma/loss), the mean scores were 28.8 on the PROPS and 29.8 on the CROPS. In contrast, those with the lowest LITE rating (i.e., a rating of 1, the estimated absence of trauma/loss), the mean scores were 7.3 on the PROPS and 8.8 on the CROPS. Comparing the distribution of PROPS and CROPS scores for these two groups, the best cutting point (for the fewest total errors) was 15 on the PROPS and 18 on the CROPS. (If one wants to add the PROPS and CROPS scores together, the cutting point would be 33.) Those cutting points yielded 6 percent false positives and 9 percent false negatives on the PROPS, and 6 percent false positives and 8 percent false negatives on the CROPS. (With a combined cutting point of 33 on the PROPS + CROPS, there would be 6 percent false positives and 6 percent false negatives.)
That approach to deriving cutting points, however, omits cases with LITE ratings of 2 (possible trauma/loss) and 3 (probable trauma/loss). Therefore, we combined the LITE ratings of 1 and 2 into one group, and three and 4 into the other, to generate alternative tentative cutting points. With this approach, the best cutting point was 16 on the PROPS and 19 on the CROPS -- each of which is one point higher than in the prior approach. (If one wants to add the PROPS and CROPS scores together, the cutting point would be 36.) These cutting points yielded 31 percent false positives and 22 percent false negatives on the PROPS, and 26 percent false positives and 25 percent false negatives on the CROPS. (With a combined cutting point of 36 on the PROPS + CROPS, there would be 24 percent false positives and 22 percent false negatives.)
These results provide preliminary support for the reliability and validity of the PROPS and CROPS scales. Each scale has high internal consistency reliability and test-retest reliability. Each scale correlated highly with an independent rating of the extent of trauma and loss experienced by the child. The high correlations are particularly impressive considering that the criterion measure was fairly crude, and that there are presumably other non-trauma/loss sources for many of the symptoms represented by the scale items. Of course, caution is indicated since these correlations are based on a single rater's estimate, based in turn on non-standardized self-report data. The apparent sensitivity of the new scales highlights the potential value of an age-appropriate trauma-focussed instrument, as opposed to the more generic anxiety and depression measures used in so many studies of children's post-traumatic symptoms.
A larger, more representative sample is needed to resolve many issues and develop norms on the instruments. Readers are reminded of the typically low response rates in this study and of the relatively high proportion of participants of minority ethnicity and whose parents did not go beyond a high school education. It is unclear to what extent the slight correlation of symptomatology with minority and parent's educational status may be due to differing response styles or to differing levels of symptoms among the various groups. This is further clouded by the failure of many responders to provide complete demographic data. It is also unclear whether the trend towards slightly higher scores for older children is a function of appropriate development, or merely reflects the additional years of opportunity for exposure to trauma and loss experiences, with associated symptomatology.
The cutoff scores should be viewed with special caution, as they were formulated only on the basis of an estimate of exposure to trauma and loss experiences. Ultimately, cutoff scores should be derived not from predictive risk factors but from concurrent assessment of symptomatology, using a parallel method such as clinical interview or other validated measures. Also, since we are measuring a continuum of symptomatology, not merely presence vs. absence, multiple cutoffs or scoring bands will probably be more useful than a single cutoff point. The cutoffs are provided here, albeit prematurely, as a convenience only.
It is disheartening to find such a high rate of child trauma and loss experiences in a community sample. Half of the children in this sample were rated as having either probably or definitely experienced significant trauma/loss, and less than 10 percent were rated as definitely having had no such experience. Although the present cutoff points are only tentative, the fact that the children's mean and median scores were at or above cutoff does not make the cutoffs invalid. In other words, child trauma/loss symptomatology may be normative. Indeed, recent research has found astonishingly high prevalence rates for prior experience of at least one Criterion A traumatic stressor among young adults - most of which presumably occurred during childhood or adolescence. For example, Riise et al (1994) found an 85 percent prevalence among a military population (mostly not military trauma), and Vrana and Lauterbach (1994) found an 84 percent prevalence among college students. When major loss is also taken into account, it becomes increasingly clear that child trauma is ubiquitous. The present findings suggest that post-traumatic symptomatology, broadly defined, may also be widespread among children.
Our decision to cover the full spectrum of children's post-traumatic reactions, rather than limiting the measure to the classic PTSD symptoms, yielded some interesting results. First of all, although numerous avoidance, intrusion, and arousal items were included on both measures, these did not emerge as discrete categories in the factor analysis, except that some avoidance and intrusion items contributed to a single factor on the CROPS. Although we do not contest the legitimacy of the PTSD diagnosis for children, these findings provide further support for the notion that children's post-traumatic reactions can be much more wide-ranging. It is also notable that we found only slight effects for age, ethnicity, and parent's education, and no gender effect, in contrast to many other child trauma studies. Although there are several possible explanations for this -- most other studies measure children's reactions to a specific event, so this study is not strictly comparable -- we believe that by including the full spectrum of children's post-traumatic symptoms, we may have maximized sensitivity and minimized bias.
We also hope to continue to improve the instruments. The CROPS lost the two main items representing pessimistic future, probably because they were too ambiguously worded to generate consistently meaningful responses. We plan to add a simpler replacement item on a trial basis. The CROPS also lost an item on bed-wetting, which children apparently refuse to endorse. We plan to add a bed-wetting item to the PROPS on a trial basis. We'd also like to shorten the scales. None of the inter-item correlations in the current findings, however, identify redundant items to delete. On both the PROPS and the CROPS, only three inter-item correlations exceed .50, with the largest being .61 on the PROPS and .62 on the CROPS.
In summary, additional work is needed to further assess, and perhaps improve, each scale. Further study is also needed to assess sensitivity to change, as well as the possibility of upwards or downwards age extension. And more can be done with construct validity, despite the encouraging factorial validity results presented here.
While awaiting further refinements and studies, however, we believe the current findings support cautious use of the scales in their present form. For example, the measures are currently being used as part of a screening battery in a post-disaster school setting; and as part of an assessment battery in a child trauma treatment outcome study. They are also being used informally at the beginning of treatment in some clinical settings, to alert therapists to possible post-traumatic issues. However, the current psychometric status of these measures precludes precise interpretation and requires the concurrent use of other, better validated, assessment tools.
Further development and use of these and other trauma-focused, age-appropriate measures will contribute to more effective study and identification of traumatized children. By targeting children grades 3-8, including both the child's and the parent's perspective, not requiring an index event, and balancing scope of symptom coverage with brevity, the CROPS and PROPS may fill a niche in child trauma assessment.
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