discussion 2

The triad of symptoms following a traumatic experience has been termed posttraumatic stress disorder (PTSD) (American Psychiatric Association 1994). Approximately 20% of individuals exposed to a significant traumatic event will develop PTSD (Breslau et al., 1998, 1999b), and children may be at even higher risk (Breslau et al., 1999a). Depending on the sample being studied and the methodology used, prevalence rates have ranged widely in at-risk child populations (American Academy of Child and Adolescent Psychiatry, 1998). For example, 34% of urban youths exposed to community violence have been reported to develop PTSD (Berman et al., 1996), chil- dren exposed to physical injury have had rates of 23% (Aaron et al., 1999), and children exposed to maltreat-

ment (i.e., physical and or sexual abuse) have been shown to have rates of 36% (Ackerman et al., 1998) or higher (see McLeer et al., 1998).

These prevalence rates highlight the need for under- standing the progression and expression of PTSD in chil- dren. Children’s initial response to trauma is often characterized by physiological and behavioral hyperarousal, and when the trauma is ongoing, the response may become complicated by dissociation (Carrion and Steiner, 2000; Perry et al., 1995). Moreover, research suggests that indi- viduals who experience chronic trauma have lower rates of recovery from PTSD (Famularo et al., 1996; Green, 1985; Terr, 1991). With evidence suggesting that chil- dren’s response to trauma can be enduring and detrimental, it has become increasingly important to ensure develop- mentally appropriate classification criteria.

Research has demonstrated that developmentally sen- sitive assessment of symptoms after trauma may be more valid than the DSM-IV criteria in very young children, because symptoms of PTSD may differ substantially between children and adults (Scheeringa et al., 1995, 2001). For example, reenactments are more likely to be expressed in play rather than through verbalizations. In addition, children are less likely to have flashbacks (Terr, 1983; Terr et al., 1999).

Accepted September 12, 2001. From Stanford University School of Medicine, Stanford, CA. This research was supported by an NIMH Minority Research Supplement

Award to Dr. Victor G. Carrion and Dr. Allan L. Reiss (RO1 MH50047). The authors thank Elana Newman, Ph.D., Natalie Pageler, Jessica Letchemanan, and the California San Mateo and San Francisco counties for their participa- tion in this project.

Reprint requests to Dr. Carrion, Division of Child and Adolescent Psychiatry and Child Development, Stanford University, Stanford, CA 94305-5719; e-mail: vcarrion@stanford.edu.

0890-8567/02/4102–0166�2002 by the American Academy of Child and Adolescent Psychiatry.

Toward an Empirical Definition of Pediatric PTSD: The Phenomenology of PTSD Symptoms in Youth

VICTOR G. CARRION, M.D., CARL F. WEEMS, PH.D., REBECCA RAY, M.A., AND ALLAN L. REISS, M.D.

ABSTRACT

Objective: To examine the frequency and intensity of posttraumatic stress disorder (PTSD) symptoms and their relation

to clinical impairment, to examine the requirement of meeting all DSM-IV symptom cluster criteria (i.e., criteria B, C, D),

and to examine the aggregation of PTSD symptom clusters across developmental stages. Method: Fifty-nine children

between the ages of 7 and 14 years with a history of trauma and PTSD symptoms were assessed with the Clinician-

Administered PTSD Scale for Children and Adolescents. Results: Data support the utility of distinguishing between the

frequency and the intensity of symptoms in the investigation of the phenomenology of pediatric PTSD. Children fulfilling

requirements for two symptom clusters did not differ significantly from children meeting all three cluster criteria with

regard to impairment and distress. Reexperience (cluster B) showed increased aggregation with avoidance and numb-

ing (cluster C) and hyperarousal (cluster D) in the later stages of puberty. Conclusions: Frequency and intensity of

symptoms may both contribute to the phenomenology of pediatric PTSD. Children with subthreshold criteria for PTSD demon-

strate substantial functional impairment and distress. J. Am. Acad. Child Adolesc. Psychiatry, 2002, 41(2):166–173. Key

Words: posttraumatic stress disorder, trauma, phenomenology, development.

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Frequency of symptoms has also been studied in older adolescents. This research has indicated that distressing recollections (reexperience), efforts to avoid thoughts and feelings (avoidance/numbing), and efforts to avoid activ- ities that facilitate recollections (avoidance/numbing) are the most common symptoms in 16- to 22-year-olds (Cuffe et al., 1998). However, data not only on the fre- quency but also on the intensity of the specific DSM-IV symptoms are needed. Previous research on pediatric anx- iety has shown that the intensity of worry is important in discriminating normative from clinical worry (Weems et al., 2000). These authors found that the intensity of worry differentiates children referred for anxiety disorder treatment (n = 119, 6 to 16 years old) from a large nor- mative comparison sample of nonreferred children, whereas frequency of worry did not differentiate the samples.

DSM-IV took a step forward with the introduction of developmental modifications to criterion A (experience of trauma) and the symptom cluster B criteria (reexperi- ence). Although symptom clusters C (avoidance and numb- ing) and D (hyperarousal) have not had developmental modifications, each of the symptom cluster criteria must be met before the diagnosis may be assigned in children and adolescents. There is little empirical evidence that the tripartite clustering of symptoms that depict adult PTSD appropriately characterize pediatric PTSD. In fact, to our knowledge, no studies have examined the clinical impor- tance of the co-occurrence of the symptom clusters in a pediatric population. Research has indicated that partial symptomatology is common (Aaron et al., 1999; Cuffe et al., 1998) and may be disabling to the point of requir- ing treatment even when full criteria are not met (see Pfefferbaum, 1997). Information on the impairment result- ing from partial symptomatology and the aggregation of the clusters may help provide future developmental mod- ifications to the current diagnostic criteria.

The aims of this study were thus to (1) examine the frequency and intensity of all 17 DSM-IV PTSD symp- toms and evaluate the relation of these symptoms to clin- ical impairment, (2) examine the requirement of meeting all DSM-IV symptom cluster criteria (i.e., criteria B, C, and D) in a pediatric sample, and (3) examine the aggre- gation (i.e., co-occurrence) of PTSD symptom clusters across developmental stages.

METHOD

Participants

The sample was recruited from local social service departments and mental health clinics. All of the children in this sample were referred

to the project because of exposure to interpersonal trauma. Therapists and caseworkers were the referring sources. We recruited only chil- dren who (1) had at least one episode of exposure to trauma, as defined by DSM-IV criterion A1 (American Psychiatric Association, 1994); (2) had undergone the trauma episode or episodes for which the indi- vidual was referred at least 6 months before referral; (3) had no known history of neurological disorders; and (4) had no known history of alcohol or drug abuse/dependence.

Sixty children were referred to this study. Consent was obtained from the participating counties’ courts for those subjects in foster place- ment (n = 27). Most cases had prior child protective services involve- ment (n = 35). A procedure was in place to report any suspected ongoing maltreatment; however, no cases were identified. The principal inves- tigator (V.G.C.) presented all subjects and their caretakers, regardless of prior court consent, with a written institutional review board–approved informed consent at a scheduled visit. All referred children underwent screening with the Child PTSD Reaction Index and were assessed with the Clinician-Administered PTSD Scale for Children and Adolescents (CAPS-CA). Only one subject was not able to complete the CAPS- CA because of scheduling problems, and he was not included in this analysis. The final sample consisted of 34 boys and 25 girls for a total sample of 59 children. The mean age of the children was 10.6 years, with a range of 7 to 14 years. Most children (55%) had experienced multiple traumatic events. Traumatic events included separation and loss (55%), witnessing violence (40%), physical abuse (37%), sexual abuse (20%), physical neglect (12%), and emotional abuse (7%). In terms of family income, 48.4% reported incomes between 0 and $31,000, 15.0% reported incomes between $31,000 and $76,000, and 14.9% of the families reported incomes over $76,000; 21.7% did not report income data (because the children were in foster care, residen- tial treatment, or other nontraditional rearing environment). In terms of education, caregivers reported partial high school education (3.3%), a high-school education (21.7%), partial college (18.3%), college (11.7%), or graduate school education (16.7%). Educational back- ground was not available for 28.3% of the sample. Ethnic composi- tion was Euro-American (n = 25), African-American (n = 26), Hispanic (n = 5), Asian (n = 2), and other (n = 1).

Instruments

The CAPS-CA (Nader et al., 1996), a structured clinical interview, is a developmentally sensitive counterpart to the CAPS for adults (Blake et al., 1995). It facilitates assessment of exposure to criterion A1 events and the individuals’ experience of these events (A2), fre- quency and intensity for each of the 17 symptoms for PTSD clus- tered in DSM-IV (i.e., criteria B, C, and D), and the 1-month duration requirement (criterion E). Additional features to increase the utility of this instrument with children include iconic representations of the behaviorally anchored 5-point frequency and intensity rating scales, opportunities to practice with the format before questions, and a stan- dard procedure for identification of the critical 1-month time frame for current symptoms. The CAPS-CA also helps evaluate the impact of symptoms (i.e., impairment; criterion F) on functioning and the overall distress related to PTSD symptoms. In this sample, the CAPS- CA total score was also significantly correlated with the Reaction Index (r = 0.51, p < .01). A certified child psychiatrist (V.G.C.) who was trained on the administration of the instrument conducted the CAPS- CA interview. Moreover, an intraclass correlation coefficient of 0.97 was established on a subsample of the interviews in the present sam- ple with one of the originators of the CAPS-CA (Dr. Elana Newman), who rated videotaped recordings of 10 interviews.

The Child PTSD Reaction Index is a 20-item self-report instru- ment used to assess PTSD symptoms after exposure to violence

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(Pynoos et al., 1987). It is a widely used instrument and has been shown to be a valid and reliable measure of PTSD symptoms in pediatric sam- ples (Nader et al., 1990). This instrument was administered as a ques- tionnaire. Subjects were instructed to ask questions if they did not understand any item or if they could not read the questionnaire. When this was the case, the questionnaire was read to them. All subjects underwent interview assessment with the CAPS-CA after screening with the Reaction Index.

The Schedule for Affective Disorders and Schizophrenia for School- Age Children–Present and Lifetime Version (K-SADS-PL) is a semi- structured clinical interview designed to identify Axis I DSM-IV disorders (Kaufman et al., 1997). This instrument was administered to the par- ticipants by a certified child psychiatrist (V.G.C.) to assess comorbidity.

Participants’ pubertal development was determined by self-report. Participants selected from drawings with written descriptions repre- senting the five Tanner stages (Marshal and Tanner, 1970) of pubic hair development and genital development for boys and breast development for girls. Children’s median pubic hair Tanner stage was 2, for girls median breast Tanner stage was 3, and for boys median genital Tanner stage was 2. For developmental analysis, the sample was split accord- ing to combined Tanner stage 2 and below 2 (53%) or above 2 (47%).

The Wechsler Abbreviated Scales of Intelligence (WASI) was used to determine intelligence (Psychological Corporation, 1999). The WASI is a nationally standardized test that yields IQ scores that correlate with subscales of the Wechsler Intelligence Scale for Children, Third Edition (WISC-III). Full-scale IQs ranged from 65 to 142, average score 90 (5 subjects scored below 70 but were included in the sample because they did not meet criteria for mental retardation because of higher adaptive behavioral functioning and their ability to participate in the clinical evaluation).

Current caretakers completed the Child Behavior Checklist (CBCL) (Achenbach, 1991), a 113-item rating scale that assesses children’s behavioral and social problems. The CBCL provides scores for both Internalizing and Externalizing subscales. CBCL scaled scores and clin- ical cut-points have been found to discriminate between clinic-referred and nonreferred children, and normative data are available (Achenbach, 1991). The subscales were used as a cross-informant measure of chil- dren’s symptoms. The CBCL has good reliability and has been exten- sively validated (Achenbach, 1991). Because some children were in foster care, residential treatment, or other nontraditional rearing envi- ronment, 48 children had complete CBCL data.

Hypotheses and Data Analyses

To examine the relation of each symptom’s frequency and inten- sity to meeting full diagnostic criteria, we addressed the following questions: (1) which symptoms are most associated with full diagno- sis? and (2) which symptoms are most associated with impairment? SPSS was used for all data analyses, including descriptive statistics, and employed an α level of p < .05 (two-tailed). We used simple lin- ear regression to examine the association between each symptom’s fre- quency (i.e., how often) and each symptom’s intensity (i.e., how distressing, how uncontrollable) and PTSD diagnosis and also with overall clinical impairment. Diagnostic status was coded (1 for full PTSD, 0 for not full PTSD). Because of the exploratory nature of the analyses and our interest in the size of the effect, we retained an α level of p < .05 (two-tailed) as recommended for such analyses (see Cohen, 1994; Jensen at al. 2001) and focused on variables that accounted for at least 10% of the variance as a way of emphasizing the size of the association as opposed to the α significance of the test statistic.

To examine the diagnostic requirement of meeting all DSM-IV symptom cluster criteria (i.e., criteria B, C, and D), the cumulative importance of the symptom clusters to impairment and distress was

examined by dividing the sample into three groups. Children meet- ing all three DSM-IV PTSD symptom cluster criteria (PTSD-3) were compared with children meeting two (PTSD-2) and children meet- ing one (PTSD-1) of the symptom cluster criteria. On the basis of our clinical observation of functional impairment in children mani- festing only some of the symptoms of PTSD, we hypothesized that children in the PTSD-1 group would show less clinical impairment than youths in the PTSD-2 and PTSD-3 groups but that there would be no difference in terms of clinical impairment between PTSD-2 and PTSD-3 children. ANOVAs or χ2 analyses were used to compare the subgroups in terms of demographics, the time since the traumatic experiences, types of traumas, comorbidity, distress, impairment, and pubertal status. Multiple comparisons between group means across the three subgroups were implemented with the Fisher least-signifi- cant-difference procedure.

We hypothesized that the symptom clusters would show increased aggregation with the emergence of puberty, because recent research indicates that the transition to puberty may be an important time in the development of internalizing symptoms, such as panic (Hayward et al., 2000). Because the reexperience criterion (criterion B) does have spe- cific developmental modifications, we expected this symptom cluster to be reported at the highest rates and that avoidance/numbing and hyperarousal (C and D, respectively) would be more common in later stages of puberty. We also hypothesized that symptom clusters C and D would show increased aggregation with cluster B with the emer- gence of puberty. We used χ2 analyses to examine the convergence of the symptom clusters.

RESULTS

Fourteen of the 59 children (24%) met full diagnos- tic criteria for PTSD on the CAPS-CA (criteria A through F). Children within the sample demonstrated a variety of comorbid psychiatric conditions as assessed by the K- SADS. The top six individual comorbid DSM-IV con- ditions were depressive disorder not otherwise specified (NOS) (12%), major depressive disorder (11%), atten- tion-deficit/hyperactivity disorder (ADHD) (11%), spe- cific phobia (9%), separation anxiety disorder (7%), and social phobia (7%). Individual disorders were collapsed into the following categories: “mood” (23%; children with either depressive disorder NOS or major depressive disorder), “externalizing” (17%; children meeting crite- ria for ADHD, conduct disorder, or oppositional defiant disorder), and “anxiety” disorders (48%; children meet- ing criteria for DSM-IV anxiety disorders other than PTSD). Although DSM-IV does not include ADHD as a disruptive behavior disorder, these conditions were com- bined in the “externalizing” category to differentiate them from anxiety and mood disorders. In addition, to pro- vide cross-informant confirmation on externalizing diag- noses, we examined the association between the CBCL Externalizing subscale and inclusion in the Externalizing disorders group. The correlation was r = 0.39, p < .05.

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The frequency and intensity of each of the DSM-IV PTSD symptoms are presented in Table 1. As can be seen in the table, the top five most frequent symptoms were avoidance of thoughts, feelings, and conversations asso- ciated with the trauma (DSM-IV cluster C, symptom number 1 [C1], 83.0%); distressing recollections (A1) and the inability to recall important aspects of the event (C3), both 70.0%; and distressing dreams (B2) and dif- ficulty concentrating (D3), both 64.0%. The three most intense symptoms were irritability/anger (D2), distress- ing dreams (B2), and detachment from others (C5).

Frequency, Intensity, and Impairment

Separate regression analyses were conducted for the frequency and intensity of each symptom on the CAPS- CA and PTSD diagnosis. Results are summarized in Table 1. As the table shows, the intensity of some symptoms predicted PTSD diagnosis or functional impairment inde- pendently of frequency. Overall, full PTSD diagnosis was most strongly associated with detachment from others, hypervigilance, and exaggerated startle for both frequency and intensity of symptoms. Separate regression analyses were conducted using the reported frequency and inten- sity of each symptom and clinical impairment (assessed by the CAPS-CA composite clinical impairment index). The results are presented in Table 1. Overall impairment was most strongly associated with distressing recollec-

tions, distressing dreams, and the inability to recall impor- tant aspects of the event for both frequency and inten- sity of the symptoms. Finally, the intensity of some symptoms predicted PTSD diagnosis or functional impair- ment when frequency did not, and the frequency of some symptoms predicted PTSD diagnosis or functional impair- ment when intensity did not.

The Three-Clusters Requirement

To examine the importance of meeting each of the symptom cluster criteria, ANOVAs with Fisher post hoc tests were conducted to compare children meeting all three DSM-IV PTSD symptom cluster criteria (PTSD-3; n = 14), children meeting criteria for all but one of the symp- tom clusters (PTSD-2; n = 23), and children meeting cri- teria for one of the symptom clusters (PTSD-1; n = 13) on continuous variables. Nine children did not meet cri- teria for any one cluster and thus were not included in these analyses. Likelihood χ2 tests were used to compare the groups on categorical variables.

Results of analyses comparing the groups on demo- graphics, comorbidity, and pubertal status are presented in Table 2. The groups did not differ with regard to gen- der, ethnicity, age, Tanner stage, or comorbid diagnoses (see Table 2). To ensure that groups did not differ in the number of traumatic experiences, time since the first trauma, time since the most recent trauma, or types of

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TABLE 1 Frequency and Intensity of DSM-IV PTSD Symptoms and Their Relation to PTSD Diagnosis and Overall Impairment

Frequency Intensity PTSD Diagnosis Overall Impairment

DSM IV Criteria No. (%) Mean (SD) R2: F R2: I R2: F R2: I

B) Reexperience 1. Distressing recollections 41 (69.5)2 1.98 (1.3)11 0.128** 0.065 0.230*** 0.260*** 2. Distressing dreams 38 (64.4)3 2.37 (0.9)2 0.79* 0.111* 0.203** 0.281*** 3. Feeling of reoccurrence 24 (40.7)10 1.67 (1.1)15 0.011 0.138** 0.144** 0.160** 4. Distress at exposure to cues 34 (57.6)5 2.26 (1.0)5 0.008 0.041 0.044 0.084* 5. Physiological reactivity to cues 19 (32.2)12 1.95 (1.1)12 0.017 0.059 0.014 0.017

C) Avoidance and numbing 1. Avoid thoughts, feelings, & conversations 49 (83.1)1 2.18 (1.2)6 0.004 0.065 0.017 0.303*** 2. Avoid places & people 35 (59.3)4 1.86 (1.1)13 0.016 0.081* 0.014 0.044 3. Inability to recall important aspects of event 41 (69.5)2 2.00 (1.1)10 0.100* 0.111* 0.194** 0.230*** 4. Diminished interest 22 (37.3)11 1.68 (0.9)14 0.064 0.060 0.117* 0.185** 5. Detachment from others 30 (50.8)6 2.30 (1.0)3 0.346*** 0.215*** 0.123** 0.109* 6. Restricted range of affect 30 (50.8)6 2.07 (0.9)8 0.054 0.010 0.109* 0.032 7. Foreshortened future 18 (30.5)13 2.28 (1.0)4 0.028 0.024 0.078* 0.044

D) Hyperarousal 1. Sleep problems 35 (59.3)4 1.86 (1.0)13 0.075* 0.087* 0.160** 0.058 2. Irritability/anger 26 (44.1)9 2.73 (1.0)1 0.004 0.012 0.026 0.006 3. Difficulty concentrating 38 (64.4)3 2.11 (0.9)7 0.034 0.111* 0.096* 0.102* 4. Hypervigilance 29 (49.2)7 2.03 (0.9)9 0.380*** 0.270*** 0.102* 0.078* 5. Exaggerated startle 28 (46.6)8 2.07 (0.9)8 0.196** 0.256*** 0.008 0.017

Note: PTSD = posttraumatic stress disorder; F = frequency of symptoms; I = intensity of symptoms. Superscript numbers represent rank. * p < .05; ** p < .01; *** p < .001.

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traumas experienced, the three groups were compared, and results indicated that the groups did not differ on any of these variables. Results from comparisons on impair- ment and distress are presented in Table 3. As Table 3 demonstrates, the PTSD-2 and PTSD-3 groups did not differ significantly on any of these variables, but both dif- fered significantly from the PTSD-1 group in terms of distress of symptoms, social impairment, school impair-

ment, overall impairment, and the percentage meeting criterion F (i.e., clinically significant impairment). Ratings on the PTSD Reaction Index and on developmental impairment did not differ across the groups.

Developmental Issues in Cluster Aggregation

The most common symptom cluster was B, with 76.0% of the sample meeting the DSM-IV criteria, followed by

TABLE 2 Comparison of Three PTSD Symptom Groups on Demographics and Comorbidity

Met Criteria for

One Symptom Two Symptom Three Symptom Cluster Clusters Clusters

Measures (n = 14) (n = 23) (n = 13) F or χ2 p

Age (years) 10.29 (1.8) 10.55 (2.1) 10.74 (2.0) 0.77 .838 % Female 35.7 47.8 35.7 0.77 .682 Ethnicity 9.6 .289

% White 42.9 39.1 57.1 % African American 50.0 43.5 21.4 % Hispanic 0.0 13.0 14.3 % Asian 7.1 4.3 0.0 % Other 0.0 0.0 7.1

Duration of trauma Time since most recent 20.07 (22.1) 31.70 (31.9) 38.00 (34.8) 1.23 .302 Time since first 58.79 (43.4) 48.08 (38.9) 64.62 (37.5) 0.79 .462

No. of traumatic experiences 2.07 (1.0) 1.83 (1.0) 2.07 (0.8) 0.42 .658 % Other anxiety disorder 41.7 56.5 50.0 0.71 .702 % Mood disorder 25.0 26.1 28.6 0.05 .977 % Disruptive disorder 14.3 26.1 14.3 1.11 .573 % Tanner stage > 2 30.8 52.2 35.7 1.89 .389 CBCL Internalizing 57.82 (13.0) 65.32 (11.6) 65.40 (9.8) 1.69 .199 CBCL Externalizing 59.09 (18.0) 69.63 (9.7) 70.10 (13.3) 2.59 .088

Note: Means with standard deviations in parentheses or percentage. PTSD = posttraumatic stress disorder; CBCL = Child Behavior Checklist.

TABLE 3 Comparison of the Three PTSD Symptom Groups in Symptom Distress and Impairment

Met Criteria for

One Symptom Two Symptom Three Symptom Cluster Clusters Clusters

Measures (n = 14) (n = 23) (n = 13) F or χ2 p

Distress of symptomsa 1.54 (0.9) 2.39 (1.0) 2.57 (1.1) 4.30 .019 Social impairmenta 0.54 (0.8) 1.52 (1.1) 1.79 (1.1) 5.67 .006 School impairmenta 0.69 (0.9) 1.76 (1.3) 2.14 (1.2) 5.38 .008 Developmental impairment 0.38 (0.8) 0.91 (1.2) 1.29 (1.1) 2.36 .106 Overall impairmenta 3.15 (2.0) 6.64 (3.4) 7.79 (3.0) 9.06 <.001 Reaction Index score 26.14 (9.2) 35.59 (12.7) 33.86 (18.1) 2.16 .126 % Meeting criterion Fa 64.3 91.3 100.0 8.96 .011

Note: Means with standard deviations in parentheses or percentage. PTSD = posttraumatic stress disorder. a Significant differences (p < .05) on Fisher post hoc test or paired χ2 with individuals meeting criteria for one symptom cluster significantly

less than individuals meeting for two or three. No significant differences were found between the group meeting criteria for two and the group meeting criteria for three symptom clusters.

cluster C (51.0%) and then cluster D (46.0%). As noted, we divided the sample between two pubertal groups (i.e., Tanner stage 2 and below versus above 2), and prelimi- nary analyses indicated that the two groups did not dif- fer in ethnicity, number of traumatic experiences, time since the first trauma, time since the most recent trauma, or types of traumas experienced. There were more girls in the group in the later stages of puberty.

The group in earlier stages of pubertal development and the older group did not differ with regard to the propor- tion of children meeting all criteria for either cluster B, C, or D. There was evidence, however, of increased aggrega- tion of the clusters with pubertal development (i.e., there was evidence that children who met one of the symptom cluster criteria tended to meet additional symptom clus- ter criteria in the older group). Specifically, the likelihood ratio χ2 test statistic indicated significant relations between cluster B and clusters C (χ2

1 = 3.83, p = .050) and D (χ2

1 = 8.97, p = .003) in the older group (i.e., Tanner stages 3, 4, and 5). In contrast, in the younger group (i.e., Tanner stages 1 and 2), the relation between cluster B and clusters C (χ2

1 = 0.19, p = .657) and D (χ2 1 = 0.01, p = .930) were

not significant. Because there were more girls in our group of children in the later stages of puberty, we next tested whether gender was responsible for the developmental findings. Girls and boys did not differ with regard to the proportion meeting full criteria for either cluster B, C, or D. In addition, there was no evidence of differential aggre- gation of the clusters with gender (i.e., there was no evi- dence that girls who met one of the symptom cluster criteria were more likely to meet additional symptom clus- ter criteria than boys).

DISCUSSION

This study contributes to the literature on the phe- nomenology of pediatric PTSD in three areas. First, data supported the utility of distinguishing between the fre- quency and the intensity of symptoms. Second, findings supported the hypothesis that children with subthresh- old criteria did not differ significantly from children meet- ing all three cluster criteria with regard to impairment and distress. Third, there was more symptom cluster aggre- gation in the later stages of puberty. In terms of the fre- quency of the symptoms, there were commonalties in symptom frequency in our sample and previous findings with older adolescents (i.e., Cuffe et al., 1998).

Our data support the utility of distinguishing between the frequency and the intensity of symptoms in the inves-

tigation of the phenomenology of pediatric PTSD. For example, the intensity of some symptoms predicted PTSD diagnosis or functional impairment independently of fre- quency. For instance, as indicated in Table 1, the inten- sity of the avoidance of feelings, thoughts, and conversations (symptom C1) and distress at exposure to cues (B4) pre- dicted functional impairment, whereas the frequency of these symptoms was not predictive of impairment. Intensity of the difficulty concentrating (D3), avoiding places and people (C2), and feelings of recurrence (B3) predicted PTSD diagnosis, whereas frequency of these symptoms did not. One reason for this finding may be that these particular symptoms are less intrinsically distressing and/or simply more common than symptoms whose frequency is predictive of impairment (e.g., restricted range of affect [C6], sense of foreshortened future [C7]). Overall, our findings point to the possibility that frequency and inten- sity may both contribute to the phenomenology of pedi- atric PTSD. Further understanding of their respective contributions may help clarify why the same degree of clinical impairment can be found in different clinical pre- sentations.

Certain symptoms predicted DSM-IV PTSD diagno- sis but not functional impairment. For example, exag- gerated startle was highly associated with PTSD diagnosis but did not correlate with impairment. This may indi- cate that certain PTSD criteria may be describing traits associated with vulnerability to the development of PTSD in childhood but are not necessarily markers of disorder impairment. Moreover, some symptoms, such as dimin- ished interest, were highly associated with impairment but not predictive of diagnosis. This may be because of a lack of developmentally appropriate descriptions of PTSD symptoms for children or alternatively, existing comorbidity, such as depression.

Our findings supported the hypothesis that children with subthreshold criteria did not differ significantly from children meeting all three cluster criteria with regard to impairment and distress. Supporting the statistical find- ings, children fulfilling diagnostic requirement for two clusters had elevated Internalizing T scores on the CBCL, and these scores were very similar to the T scores of chil- dren meeting criteria for three clusters. In addition, our findings suggest that the impairment found on sub- threshold (PTSD-2) children is not due to comorbidity but rather is specific to the posttraumatic symptoms pre- sent, because there were no significant differences among the groups in terms of comorbidity or other demographic

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variables. Taken together, our results suggest that rather than seeking a threshold number of symptoms, a more precise diagnosis of pediatric PTSD could be developed by evaluating the intensity of symptoms and their rela- tion to functional impairment.

Finally, our findings suggest that developmental mod- ifications to symptom clusters C (Avoidance and Numbing) and D (Hyperarousal) as done with B (Reexperience) may be useful. As expected, there was evidence of increased aggregation of the clusters with pubertal development (i.e., there was evidence that children who meet the symp- tom cluster B criteria tended to meet criteria for additional symptom clusters in the developmentally older group but not in the younger group). This may indicate that the cur- rent diagnostic criteria may not be appropriate for chil- dren. In other words, our results suggest that the absence of this triad does not indicate a lack of posttraumatic stress problems in children but may be due to developmental differences in symptom expression. The significant seque- lae of early trauma, as indicated by the levels of impair- ment, distress, and comorbidity, should be recognized early to provide appropriate interventions.

Limitations

Our findings are limited by the multiple group com- parisons made, a relatively small sample size, and a cross- sectional design. It will therefore be important to replicate these findings in larger samples with additional informants and longitudinal designs. Our failure to demonstrate age differences in the prevalence of symptom clusters might be a function of age range as well as sample size. Specifically, because the age range was narrow, we compared only two groups of Tanner stage children. Although we examined the time since trauma, number of traumas, and types of trauma, we did not specifically measure severity of trauma or duration of trauma. Future research is thus needed to examine the role of severity and duration of trauma in pediatric PTSD symptom expression. Other characteris- tics of the trauma, such as proximity and number of per- petrators, may also have an impact on PTSD symptom expression. Although previous investigations have shown children to be as valid informants of internalizing symp- toms, such as fear, as their parents (Weems et al., 1999), researchers may wish to use additional informants to assess externalizing symptoms in PTSD samples. The fact that the K-SADS was given only to the children may have lim- ited our evaluation of externalizing disorders; however, the CBCL Externalizing subscale and inclusion in the

externalizing disorders group were significantly associated in our sample.

Clinical Implications

Children with subthreshold PTSD should be evalu- ated for functional impairment and distress and be given appropriate recommendations for treatment even when they do not fulfill DSM-IV criteria. Results suggest that certain items were strongly associated with full diagno- sis and/or impairment. Clinicians may wish to use these items when screening children who have experienced traumatic stress. Early recognition of the sequelae of trauma in children may help prevent disturbance on the acquisition of cognitive, social, and emotional milestones. Trauma can interrupt, either temporarily or permanently, the attainment of these skills, compromising the indi- vidual’s abilities to learn, interact with others, and regu- late mood (Perry, 1994; Pfefferbaum, 1997).

Behaviors such as hyperactivity, learning difficulties, hypervigilance, and emotional dysfunction that begin after the experience of a traumatic event or events sug- gest neural mechanisms requiring study. Behavioral obser- vations of children who experience trauma should guide these investigations. Our results suggest that the behav- ioral description of pediatric PTSD should be improved. The data from this study may facilitate a better descrip- tion of pediatric PTSD phenomenology.

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