Predictive validity of acute stress disorder in children and adolescents

Adult research suggests that the dissociation criterion of acutestress disorder has limited validity in predicting post-traumaticstress disorder (PTSD). We addressed this issue in child andadolescent survivors (n=367) of road accidents. Dissociationaccounted for no significant unique variance in later PTSD,over and above other acute stress disorder criteria. Furthermore,thresholds of either three or more re-experiencing symptoms,or six or more re-experiencing/hyperarousal symptoms, were as effective at predicting PTSD as the full acute stress disorderdiagnosis.

INTRODUCTION

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INTRODUCTION

In the aftermath of trauma, an important challenge involvesidentifying individuals who will later develop post-traumaticstress disorder (PTSD).¹ The diagnosis of acute stress disorder,which differs from PTSD in its requirement of three or moredissociative symptoms (e.g. derealisation), was introduced to meet this challenge.^2,3 The rationale is that dissociationin the acute phase can identify those at risk of later PTSD.² However, research suggests that dissociation actually accountsfor little unique variance in predicting PTSD in adults,⁴thus questioning the validity of acute stress disorder. Giventhe significant concerns about the dissociation mandate inadults, it is important to fully assess whether dissociationhas predictive utility in trauma-exposed youth. Our primaryaim was therefore to examine the predictive utility of the acute stress disorder dissociation criterion in children and adolescentsin a large sample, homogeneous for type of trauma. To thisend, we combined data from the three published studies in childrenand adolescents.^5–7 Our second aim was to examine whetherindividual symptom counts across the different acute stressdisorder/PTSD symptom criteria assessed in the month post-traumacan perform as well as full acute stress disorder in predicting later PTSD in children and adolescents.

Method

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Method

Data from hospital-attending, trauma-exposed child and adolescentroad traffic accident survivors (n=367, 117 female) aged 6–17years (mean=11.88, s.d.=2.60) were pooled from three centres:Oxford (n=86, aged 6–17 years);⁶ London (n=41, aged 10–16);⁵ and Philadelphia (n=240, aged 8–17).⁷ Written, informed consent was obtained from caregivers andassent from children. Of the 367 individuals, 285 were followedup at 6 months (n=82, n=29 and n=174 respectively). Participant recruitment and flow details are presented elsewhere.^5–7 Diagnoses were based on widely used instruments with robustpsychometrics, as follows. Acute stress disorder was assessedat 2–4 weeks (baseline) using either structured clinicalinterview (London), the Child Acute Stress Questionnaire⁸ (Philadelphia),or a combination of questionnaire and interview (Oxford). At6 months PTSD was assessed using the Anxiety Disorder Interview Schedule,⁹ the Clinician-Administered PTSD Scale for Childrenand Adolescents,¹⁰ or the Childhood PTS Reaction Index^11,12 respectively.

Results

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Results

At baseline 9% (n=33; 16 females) of the pooled sample met criteriafor acute stress disorder and 23% (n=83; 38 females) for sub-acutestress disorder (acute stress disorder minus dissociation),with 7% (n=25; 12 females) meeting criteria for PTSD at 6 months. Point-biserial correlations revealed no significant associationsbetween age and presence of these diagnoses (P>0.4). Asinitial analyses revealed no significant effects involvingresearch centre (coded by dummy variables) (P>0.2) reportedanalyses utilised the pooled sample.

As expected, baseline presence of acute stress disorder correlated significantly with 6-month PTSD ( ${varphi}$ (283)=0.18, P<0.01). Stepwiselogistic regression predicting 6-month PTSD, with subacute stress disorder on step 1 and the acute stress disorder dissociationcriterion on step 2, revealed sub-acute stress disorder asa significant predictor of PTSD (Wald=22.39, P<0.001), whereasdissociation provided no significant increment in PTSD prediction(Wald=0.48, P>0.48).

Table 1 shows the ability of different baseline acute stressdisorder/PTSD symptom counts to predict PTSD at follow-up.In adult violent crime victims, six or more baseline symptomsof hyperarousal and/or re-experiencing predicted later PTSDas effectively as did full acute stress disorder, in termsof the trade-off between specificity and sensitivity.¹ It is clear from Table 1 that this threshold, and even a thresholdof three or more re-experiencing symptoms, was if anything,somewhat better than the full acute stress disorder diagnosisin its balance of sensitivity and specificity for the presentsample. Furthermore, adding full acute stress disorder (onstep 2) to either of these symptom counts on step 1 in logisticregressions, to predict later PTSD, provided no significantindependent predictive benefits for acute stress disorder (Wald=0.71,P>0.4) over and above the predictive effects of either symptomthreshold alone (Wald>14.34, P<0.001).

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Table 1 Ability to predict PTSD at 6 months by varying acute stress disorder/PTSD symptom counts at 2-4 weeks

Discussion

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Discussion

The acute stress disorder dissociation criterion appears tohave no unique role in the prediction of later PTSD in a largesample of young trauma survivors, homogeneous for trauma type.The significant association between acute stress disorder andlater PTSD may therefore simply reflect persistence or chronicityin the symptom clusters that acute stress disorder and PTSDhave in common. Indeed, sub-acute stress disorder (acute stressdisorder minus dissociation) was almost three times more sensitivethan full acute stress disorder in predicting PTSD (Table 1).Thus, these data cast doubt on the predictive validity of the acute stress disorder diagnosis in younger people.

Presence of three or more re-experiencing symptoms at baselinewas as effective at predicting later PTSD as the full acutestress disorder diagnosis, and possibly better. Indeed, thefull diagnosis provided no significant increment in PTSD predictionover and above this simple threshold. Similar results werefound for a count of six or more hyperarousal/re-experiencingsymptoms. However, sensitivities for both of these thresholdswere less than 50%, suggesting that they are not an effective screen.

Study limitations are that diagnoses were derived differentlyacross the three centres on samples with different age rangesand the focus on a single-incident civilian trauma.

REFERENCES

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