A Randomized Controlled Trial of Exposure Therapy

Journal of Consulting and Clinical Psychology 2008, Vol. 76, No. 4, 695–703

Copyright 2008 by the American Psychological Association 0022-006X/08/$12.00 DOI: 10.1037/a0012616

A Randomized Controlled Trial of Exposure Therapy and Cognitive Restructuring for Posttraumatic Stress Disorder Richard A. Bryant, Michelle L. Moulds, Rachel M. Guthrie, Suzanne T. Dang, Julie Mastrodomenico, Reginald D.V. Nixon, Kim L. Felmingham, and Sally Hopwood University of New South Wales

Mark Creamer University of Melbourne Previous studies have reported that adding cognitive restructuring (CR) to exposure therapy does not enhance treatment gains in posttraumatic stress disorder (PTSD). This study investigated the extent to which CR would augment treatment response when provided with exposure therapy. The authors randomly allocated 118 civilian trauma survivors with PTSD to receive 8 individually administered sessions of either (a) imaginal exposure (IE), (b) in vivo exposure (IVE), (c) IE combined with IVE (IE/IVE), or (d) IE/IVE combined with CR (IE/IVE/CR). There were fewer patients with PTSD in the IE/IVE/CR (31%) condition than the IE (75%), IVE (69%), and IE/IVE (63%) conditions at a 6-month follow-up assessment. The IE/IVE/CR condition resulted in larger effect sizes than each of the other conditions in terms of PTSD and depressive symptoms. These findings suggest that optimal treatment outcome may be achieved by combining CR with exposure therapy in treating PTSD patients. Keywords: posttraumatic stress disorder, cognitive behavior therapy, exposure therapy, randomized controlled trial

feared stimulus (e.g., traumatic memories or feared situations) leads to emotional processing of affective information, habituation of anxiety, integration of corrective information, and eventual mastery of the experience (Foa & Hearst-Ikeda, 1996). CR is based on the notion that identifying and modifying catastrophic and unrealistic interpretations of one’s traumatic experience and future well-being will lead to symptom reduction because the resulting cognitive schema will not result in psychopathological states. This approach has strong theoretical and empirical support from work that has demonstrated that maladaptive appraisals contribute strongly to PTSD development and maintenance (Ehlers & Clark, 2000; Ehlers, Mayou, & Bryant, 1998). Several studies have attempted to address the potential benefits of adding CR to exposure. Marks et al. (1998) found that exposure alone, CR alone, and these interventions combined resulted in equivalent PTSD symptom reduction. Resick et al. (2002) found that cognitive processing therapy (predominantly CR combined with a small dose of exposure) and IE alone resulted in comparable gains. In another study, Foa et al. (2005) found that IE alone is more effective than combining IE with CR. A similar finding was discovered in a comparison of CBT (that involved CR and exposure therapy) and exposure alone in refugees with PTSD (Paunovic & Ost, 2001). In contrast, there is tentative evidence of an additive gain when combining CR with exposure. Bryant et al. (2003) found that combining IE and CR led to greater reductions in PTSD than did IE alone. This study was limited, however, because it employed only IE, and it is possible that it found an additive gain when using CR because the study did not use the full repertoire of exposure (i.e., IVE).

Although there is strong evidence that cognitive behavior therapy (CBT) is the most efficacious treatment for posttraumatic stress disorder (PTSD; Foa & Meadows, 1997; Harvey, Bryant, & Tarrier, 2003), there is a need to better understand the potent components of CBT because meta-analyses indicate that approximately 56% of patients recover from PTSD after CBT (Bradley, Greene, Russ, Dutra, & Westen, 2005). There is outstanding debate about the optimal components of CBT. Across numerous studies there is convergent evidence that prolonged imaginal exposure (IE), in vivo exposure (IVE), and cognitive restructuring (CR) are efficacious in reducing PTSD symptoms following sexual assault (Foa, Dancu, et al., 1999; Foa et al., 2005; Foa, Rothbaum, Riggs, & Murdock, 1991; Marks, Lovell, Noshirvani, Livanou, & Thrasher, 1998; Resick, Nishith, Weaver, Astin, & Feuer, 2002) in mixed civilian trauma samples (Bryant, Moulds, Guthrie, Dang, & Nixon, 2003; Tarrier et al., 1999). The outstanding debate involves the potential additive benefit of combining exposure and CR (Marks, 2000). Both IE and IVE presume that exposure to the

Richard A. Bryant, Michelle L. Moulds, Rachel M. Guthrie, Suzanne T. Dang, Julie Mastrodomenico, Reginald D.V. Nixon, Kim L. Felmingham, and Sally Hopwood, School of Psychology, University of New South Wales, Sydney, New South Wales, Australia; Mark Creamer, Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia. This research was supported by National Health and Medical Research Council Program Grant 300304 to Richard A. Bryant and Mark Creamer. Correspondence concerning this article should be addressed to Richard A. Bryant, School of Psychology, University of New South Wales, Sydney, New South Wales 2052, Australia. E-mail: [email protected] 695

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It has been proposed that a possible reason previous studies have not found an additive gain when combining these efficacious treatments is because time constraints resulted in less of the active treatment components being provided in the combined conditions (Foa, 2000). That is, patients receiving combined treatments may receive less exposure or CR because both these components need to be delivered within a fixed time. The current study aimed to clarify the issue of combining exposure and CR by addressing the limitations of previous studies. We compared four conditions: (a) IE, (b) IVE, (c) combined IE and IVE (IE/IVE), and (d) combined IE, IVE, and CR (IE/IVE/CR). This design improved on previous studies in several key ways. First, we ensured that the active component of each intervention was carefully matched in each condition by adding supportive counseling to those conditions that did not include the full complement of treatment components. In this way, we matched overall therapy time and at the same time ensured that patients in single or combined treatments received comparable amounts of specific therapy components. Second, we were also interested in the relative merits of the different forms of exposure. Accordingly, we compared IE against IVE. Only one uncontrolled study has done this comparison before and found that IVE was more effective than imaginal exposure in reducing avoidance (Richards, Lovell, & Marks, 1994). Devilly and Foa (2001) have argued that studies that integrate IVE and IE perform better than those with IE alone, arguably because exposure to feared stimuli may facilitate greater mastery of avoidance behaviors. Although previous studies have found that combined therapies do not provide additive therapeutic gains, we suggest that these results may have occurred as a result of the previously described methodological problems in those studies. On the basis that both IE and CR have demonstrated efficacy in reducing PTSD symptoms, we hypothesized that the IE/IVE/CR condition would be more efficacious in reducing PTSD symptoms than the other conditions. Additionally, we hypothesized that combining IE and IVE would provide better outcomes than either form of exposure alone. Finally, we hypothesized that IVE would be more beneficial than IE because of proposals that live exposure leads to greater learning than imaginal exposure (Devilly & Foa, 2001), and initial evidence supports this proposal (Richards et al., 1994).

Mental Disorders (4th ed.; DSM–IV; American Psychiatric Association, 1994) criteria, determined by the CAPS. Exclusion criteria included history of psychosis, organic brain syndrome, substance dependence, current suicidal risk, inability to converse in English, or being less than 17 or more than 60 years of age. Participants were initially screened by telephone, and full assessments were conducted only on participants who did not report any exclusion criteria on telephone screening. All participants completed written informed consent approved by the Westmead Hospital human research ethics committee.

Procedure A single-rate blind randomized control trial comparing four cognitive behavioral treatments of civilian chronic PTSD was conducted. Participants were informed that they would be randomly allocated to one of four treatments. Randomization was conducted by a process of minimization stratified on gender, trauma type, and PTSD total score. Participants were randomly assigned according to a random numbers system, which was administered by an individual at the University of New South Wales who was independent of the study and who worked at a site that was distant from the treatment center. This procedure ensured that randomization was not influenced by participant characteristics. Every 3 months allocation was amended to ensure that gender, trauma type, and PTSD severity were balanced across conditions. Figure 1 summarizes the participant flow. A total of 118 participants were randomized into the study and allocated to either IE (n ⫽ 31), IVE (n ⫽ 28), IE/IVE (n ⫽ 31), or IE/IVE/CR (n ⫽ 28). Of these, 90 participants (82%) completed treatment, and 84 (71%) completed the 6-month follow-up assessment. Initial assessments were conducted at pretreatment, prior to randomization. Posttreatment and 6-month follow-up assessments were conducted by independent clinicians who were unaware of the treatment condition of participants. Experimental blindness was maintained by ensuring that clinicians who conducted assessments did not have access to (a) participant notes or (b) treatment allocation of participants.

Measures Method Sample Size Estimation This study based its sample sizes on a previous trial that compared IE exposure alone versus IE combined with CR (Bryant et al., 2003). Using these data on treatment completers at a 6-month follow-up, we estimated that with 80% power and two-sided ␣ ⫽ .05, n ⫽ 30 per group would be needed to detect an anticipated meaningful follow-up difference on the Clinician-Administered PTSD Scale (CAPS; Blake et al., 1995).

Patients Participants were consecutive civilian trauma survivors who were referred to the Westmead Hospital Traumatic Stress Clinic between March 2001 and May 2005 following nonsexual assault or motor vehicle accident and who displayed PTSD of at least 3 months’ duration based on Diagnostic and Statistical Manual of

Primary measure. We determined PTSD diagnostic status using the CAPS (Blake et al., 1995). The CAPS is a structured clinical interview that indexes the 17 symptoms described by the DSM–IV PTSD criteria. Each symptom is rated on a 5-point scale in terms of the severity and frequency of the symptom in the past week. The CAPS possesses good sensitivity (.84) and specificity (.95) relative to the Structured Clinical Interview for the DSM–IV PTSD diagnosis and also possesses sound test–retest reliability (.90 –.80; Blake et al., 1995). Secondary measures. Additional psychopathology measures included the Beck Depression Inventory (2nd ed.; BDI; Beck, Steer, & Brown, 1996), the Impact of Event Scale (IES; Horowitz, Wilner, & Alvarez, 1979), and the State–Trait Anxiety Inventory—State Scale (STAI; Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983). To index changes in cognitive processes, we also administered the Catastrophic Cognitions Questionnaire (CCQ; Khawaja & Oei, 1992). The CCQ is a 21-item self-report measure that indexes catastrophic thinking about emotional reactions, so-

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Figure 1.

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Patient participation in study. PTSD ⫽ posttraumatic stress disorder.

matic sensations, and mental processes. It possesses sound concurrent validity with the Agoraphobic Cognitions Questionnaire and Body Sensations Questionnaire (Chambless, Caputo, Bright, & Gallagher, 1984) and strong internal consistency and test–retest reliability (Khawaja, Oei, & Baglioni, 1994). At the completion of Session 1 and after the rationale had been explained, participants rated their confidence in the treatment (1 ⫽ not at all confident, 10 ⫽ extremely confident) and the logic of the treatment (1 ⫽ not at all logical, 10 ⫽ extremely logical). All measures were administered at each assessment, with the exception of therapy confidence and logic ratings.

Treatment Conditions Individual therapy was conducted by one of six masters-level clinical psychologists, who were trained to use treatment manuals and who received weekly supervision from Richard A. Bryant. Treatment comprised 8 once-weekly 100-min sessions with structured daily homework activities. Imaginal exposure (IE). Session 1 focused on psychoeducation, the rationale of exposure, and obtaining a narrative of the traumatic memory. Sessions 2 to 7 focused on imaginal exposure to traumatic memories. Participants were instructed to provide a

narrative of their trauma that involved reciting the experience in the first person and present tense, with explicit instructions to focus on the full range of sensory and affective responses to the trauma. The narrative was repeated if necessary in order to ensure that exposure occurred for 40 min. At the completion of the exposure, therapists discussed the exposure experience with participants but refrained from engaging in discussions that involved CR. Participants were given explicit instructions to rehearse the exercise on a daily basis between sessions. Monitoring forms for IE were completed during sessions and for daily homework. Monitoring forms were used to ensure homework completion. Each session included 40 min of IE, 50 min of supportive counseling, and 10 min of homework assignments at the end of the session to ensure equivalent time within sessions for the IVE and IVE/CR groups was devoted to IE. Session 8 focused on relapse prevention that employed imaginal exposure-based strategies. In vivo exposure (IVE). Session 1 focused on psychoeducation, the rationale of IVE, and initiation of development of a hierarchy of feared situations. Sessions 2 to 7 focused on implementation of the hierarchy and establishing prescribed homework assignments to approach and remain in feared situations until the participant’s anxiety had reduced by 50%. Participants were given

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explicit instructions to rehearse the exercise on a daily basis between sessions. Each session included 25 min of IVE instructions, 65 min of supportive counseling, and 10 min of homework assignments. In vivo exercises were conducted when appropriate within session (e.g., requiring an assault survivor to sit in the waiting room in the presence of unfamiliar men), however the majority of time was devoted to establishing and reviewing exercises conducted outside of sessions. All PTSD patients were able to identify situational factors that elicited distress that could be structured within an in vivo hierarchy program. Session 8 focused on relapse prevention that employed IVE-based strategies. Imaginal exposure/in vivo exposure (IE/IVE). Session 1 focused on psychoeducation, the rationale of IE and IVE, initiation of development of a hierarchy of feared situations, and obtaining a narrative of the traumatic memory. Sessions 2 to 7 focused on imaginal exposure to traumatic memories. In addition, participants completed the in vivo exercises described above. These sessions included 40 min of IE, 25 min of IVE, 25 min of supportive counseling, and 10 min of homework assignments. Session 8 focused on relapse prevention that employed both IE- and IVEbased strategies. Imaginal exposure/in vivo exposure/cognitive restructuring (IE/ IVE/CR). Session 1 was devoted to psychoeducation and education about exposure and cognitive restructuring. In subsequent sessions, participants were taught to identify dysfunctional, unrealistic, and catastrophic thoughts about their traumatic experience, themselves, and their future well-being. Participants were instructed in daily monitoring of thoughts and affective states and to modify thoughts by Socratic questioning, probabilistic reasoning, and evidence-based thinking (Beck, Emery, & Greenberg, 1985). Sessions comprised 25 min of CR, 40 min of IE, 25 min of IVE, and 10 min of homework assignments. The final session addressed relapse prevention involving IE-, IVE-, and CR-based strategies.

assumes that those participants who dropped out remained unchanged across the duration of the study (Everitt, 1998). We adopted the LOCF procedure because it has been the standard practice followed in previous PTSD trials, and reporting of completer analyses allows us to check for biases potentially introduced in the LOCF procedure. We followed the same procedure for the secondary measures (IES, STAI, BDI, and CCQ). Effect sizes were calculated for posttreatment and follow-up outcomes by comparing the IV, IE/IV, and IE/IV/CR conditions against the IE condition, which served as the comparison group. This decision was made because of evidence that IE is not as effective as IV (Richards et al., 1994) and because of proposals that IE may not be as beneficial as IV in reducing PTSD symptoms (Devilly & Foa, 2001). We derived Cohen’s d effect size by calculating the mean difference between assessments of each treatment condition and dividing this by the pooled standard deviation (Cohen, 1988). Following the International Society for Traumatic Stress Studies treatment guidelines for PTSD (Foa, Keane, & Friedman, 2000), we then used Hedges G effect sizes to correct for variations due to small sample sizes (Hedges, 1982). We calculated high end-state functioning as being below specific cutoff scores for measures on both PTSD and depression at the follow-up assessment. We adopted a conservative estimate of good end-state functioning for PTSD by following an established cutoff score of 19 on the CAPS (combining frequency and intensity scores) as a measure of the absence of PTSD (Weathers, Keane, & Davidson, 2001). In addition, we used an established cutoff of 10 on the BDI (Kendall, Hollon, Beck, Hammen, & Ingram, 1987). Finally, we calculated Jacobson and Truax’s (1991) third operational definition for clinically significant change, which resulted in a cutoff of ⬍45 on the CAPS at follow-up.

Treatment Fidelity

Preliminary Analyses

Audiotapes of 70 therapy sessions (9% of the 808 therapy sessions) were randomly selected and rated by three clinicians experienced in cognitive behavior therapy who were independent of the study. Raters listened to audiotapes and rated the presence or absence of each of 35 treatment components, without regard to treatment condition or treatment session. It is important that raters also noted the time spent on each component. Raters also indicated the quality of the therapy provided on a 7-point scale (1 ⫽ unacceptable, 7 ⫽ very good). No IE or IVE session included the other form of exposure or CR. No treatment session varied from the designated amount of time devoted to IE, IVE, or CR by more than 8 min. The mean quality ratings for treatment components across conditions was 6.1 (SD ⫽ 1.58).

Table 1 presents the demographic characteristics for each treatment condition. One-way analyses of variance (ANOVAs) of participants’ demographic characteristics and pretreatment psychopathology measures indicated no differences between treatment groups on any variable. Planned comparisons of treatment completers and treatment dropouts indicated that those who dropped out of treatment had higher CAPS scores, t(1, 116) ⫽ 4.02, p ⬍ .001, and higher BDI scores, t(1, 116) ⫽ 2.50, p ⬍ .05, than did those who completed treatment. These participants did not differ on any other pretreatment variables.

Data Analysis To index the relative effects of the four treatments on the primary outcome measure (CAPS), we conducted analyses of covariance (ANCOVAs) for (a) posttreatment and (b) follow-up data that controlled for baseline CAPS score. We report both intent-to-treat analyses, in which we employed the last observation carried forward (LOCF) procedures, and completer analyses. We recognize that the LOCF procedure can be problematic because it

Results

Intent-to-Treat Analyses Primary outcome measure. Table 2 presents the mean psychopathology scores for the intent-to-treat sample. The ANCOVA on posttreatment responses indicated a main effect for CAPS, F(3, 113) ⫽ 4.20, p ⬍ .01. Post hoc Tukey comparisons indicated that IE/IVE/CR participants scored lower than did each of the other groups on CAPS scores ( p ⬍ .05). In terms of follow-up analyses, the ANCOVA indicated a main effect for CAPS, F(3, 113) ⫽ 4.43, p ⬍ .005. Post hoc Tukey comparisons indicated that IE/IVE/CR participants scored lower than each of the other groups on CAPS scores ( p ⬍ .05). At posttreatment there were no significant

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Table 1 Participant Characteristics Variable

Imaginal exposure

In vivo exposure

Imaginal/in vivo exposure

Imaginal/in vivo exposure/ cognitive restructuring

Age, in years Time since trauma, in months NART score Gender, n Male Female Ethnic status, n White Asian Employed Trauma type, % MVA Assault Logic rating Confidence rating CAPS IES–Intrusions IES–Avoidance STAI BDI CCQ

39.13 (10.87) 19.00 (7.63) 29.42 (10.30)

40.92 (15.82) 21.15 (21.47) 27.67 (11.85)

35.85 (12.31) 19.44 (27.22) 25.00 (10.02)

33.75 (9.42) 20.92 (37.16) 25.54 (8.86)

42 58

25 22

31 22

20 27

28 3 24

26 2 24

29 2 26

25 3 25

37 63 8.39 (1.40) 7.58 (2.04) 73.29 (18.82) 24.48 (7.56) 29.10 (6.03) 59.10 (15.08) 24.03 (10.81) 72.16 (15.79)

46 54 8.73 (1.37) 6.83 (2.29) 76.79 (15.53) 24.21 (10.55) 22.68 (10.52) 58.25 (15.62) 25.38 (12.82) 68.29 (16.63)

44 56 8.48 (1.33) 7.29 (2.19) 76.06 (19.19) 27.58 (8.72) 27.61 (8.50) 59.32 (12.75) 24.23 (11.38) 68.84 (18.88)

50 50 8.44 (1.04) 6.52 (2.52) 71.35 (17.28) 24.89 (8.01) 23.71 (8.63) 56.93 (12.75) 21.79 (10.25) 66.50 (18.73)

Note. Data are means (standard deviations) unless otherwise noted. NART ⫽ National Adult Reading Test; MVA ⫽ motor vehicle accident; CAPS ⫽ Clinician-Administered PTSD Scale; IES ⫽ Impact of Event Scale; STAI ⫽ State–Trait Anxiety Inventory (State Scale); BDI ⫽ Beck Depression Inventory; CCQ ⫽ Catastrophic Cognitions Questionnaire.

differences in rates of PTSD between the IE (63%), IVE (65%), IE/IVE (59%), and the IE/IVE/CR (35%) groups, ␹2(1, N ⫽ 103) ⫽ 6.24, p ⬍ .10. At follow-up, there were fewer participants with PTSD in the IE/IVE/CR (31%) than the IE (75%), IVE (69%), and IE/IVE (63%) groups, ␹2(1, N ⫽ 103) ⫽ 12.42, p ⬍ .01. Secondary measures. In terms of secondary measures, separate ANCOVAs on posttreatment measures indicated no main effects. At follow-up, ANCOVAs indicated significant effects for IES–Intrusions, F(3, 113) ⫽ 4.19, p ⬍ .05; IES–Avoidance, F(3,

113) ⫽ 3.45, p ⬍ .05; BDI, F(3, 107) ⫽ 2.83, p ⬍ .05; and CCQ, F(3, 107) ⫽ 2.83, p ⬍ .05. Post hoc Tukey comparisons indicated that IE/IVE/CR participants scored lower than did each of the other groups on IES–Intrusions ( p ⬍ .05), IES–Avoidance ( p ⬍ .05), BDI ( p ⬍ .05), and CCQ ( p ⬍ .05). Table 3 presents the between-group effect sizes for posttreatment and follow-up measures. Relative to the gains made by participants in the IE condition, participants in the IE/IVE/CR condition generally displayed moderate to large effect sizes (between 0.5%– 0.8%) on most measures. In comparisons, partici-

Table 2 Psychopathology Measures for Intent-to-Treat Analyses Outcome measure

Imaginal exposure

CAPS IES–Intrusions IES–Avoidance STAI BDI CCQ

55.50 (33.83) 19.94 (8.62) 20.58 (11.52) 50.71 (16.36) 21.13 (13.23) 71.52 (19.15)


59.94 (32.36) 20.87 (10.40) 21.13 (10.56) 56.19 (16.03) 20.58 (12.83) 67.16 (22.25)



Posttreatment 55.96 (24.56) 17.25 (11.83) 17.54 (12.29) 50.36 (18.68) 19.36 (11.28) 64.93 (20.15)

55.39 (37.45) 20.81 (13.17) 21.81 (14.31) 48.87 (16.74) 22.16 (15.44) 62.19 (18.28)

29.86 (27.11) 14.07 (10.58) 13.14 (11.00) 46.46 (17.21) 13.96 (12.05) 57.39 (20.72)

Follow–up 59.32 (29.62) 19.21 (12.58) 17.57 (10.85) 51.14 (17.88) 19.79 (12.43) 67.32 (15.60)

56.39 (35.87) 23.05 (12.14) 25.16 (15.14) 54.84 (15.44) 24.81 (14.90) 66.56 (16.10)

32.86 (27.44) 13.35 (11.01) 13.18 (12.58) 46.89 (24.54) 13.54 (11.85) 55.18 (20.36)

In vivo exposure

Note. Data are means (standard deviations). CAPS ⫽ Clinician-Administered PTSD Scale; IES ⫽ Impact of Event Scale; STAI ⫽ State–Trait Anxiety Inventory (State Scale); BDI ⫽ Beck Depression Inventory; CCQ ⫽ Catastrophic Cognitions Questionnaire.

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Table 3 Between-Treatment Condition Effect Sizes on Outcome Measures for Intent-to-Treat and Completer Analyses Posttreatment Outcome measure CAPS IES–Intrusions IES–Avoidance STAI BDI CCQ


Follow-up

IE – IV

IE ⫺ IE/IV

IE ⫺ IE/IV/CR

IE – IV

IE ⫺ IE/IV

IE ⫺ IE/IV/CR

0.03 (⫺0.48, 0.54) 0.26 (⫺0.25, 0.77) 0.25 (⫺0.26, 0.77) 0.02 (0.49, 0.53) 0.33 (⫺0.18, 0.85) 0.33 (⫺0.18, 0.85)

0.01 (⫺0.48, 0.51) 0.08 (⫺0.42, 0.58) 0.09 (⫺0.40, 0.59) 0.11 (⫺0.39, 0.61) 0.49 (⫺0.01, 1.10) 0.49 (⫺0.01, 1.00)

Intent-to-Treat 0.81 (0.27, 1.34) 0.60 (0.08, 1.13) 0.65 (0.13, 1.18) 0.25 (⫺0.26, 0.76) 0.70 (0.17, 1.23) 0.70 (0.17, 1.23)

0.02 (⫺0.49, 0.53) 0.10 (⫺0.41, 0.61) 0.32 (⫺0.19, 0.84) 0.29 (⫺0.22, 0.81) 0.06 (⫺0.45, 0.57) 0.00 (0.09, 1.12)

0.10 (⫺0.40, 0.60) 0.13 (⫺0.36, 0.63) 0.30 (⫺0.20, 0.81) 0.08 (⫺0.41, 0.58) 0.30 (⫺0.20, 0.80) 0.03 (⫺0.47, 0.53)

0.89 (0.35, 1.42) 0.47 (0.05, 0.99) 0.68 (0.15, 1.20) 0.45 (⫺0.07, 0.97) 0.56 (0.04, 1.08) 0.55 (0.03, 1.07)

⫺0.14 (0.44, 0.73) 0.27 (⫺0.32, 0.86) 0.10 (⫺0.49, 0.68) 0.10 (⫺0.48, 0.69) 0.00 (⫺0.58, 0.58) 0.02 (⫺0.56, 0.60)

0.26 (0.33, 0.85) 0.24 (⫺0.35, 0.83) 0.06 (⫺0.54, 0.65) 0.31 (⫺0.29, 0.90) 0.27 (⫺0.32, 0.86) 0.67 (0.06, 1.28)

Completer 0.88 (0.28, 1.48) 0.64 (0.05, 1.22) 0.45 (⫺0.13, 1.03) 0.22 (⫺0.35, 0.80) 0.46 (⫺0.12, 1.04) 0.53 (⫺0.05, 1.12)

0.19 (0.28, 1.55) 0.03 (⫺1.42, 1.48) 0.08 (⫺0.52, 0.69) 0.22 (⫺0.38, 0.83) 0.21 (⫺0.39, 0.82) 0.57 (⫺0.05, 1.18)

0.28 (⫺0.42, 0.79) 0.07 (⫺1.38, 1.52) 0.08 (⫺0.52, 0.69) 0.17 (⫺0.44, 0.77) 0.20 (⫺0.41, 0.81) 0.38 (⫺0.23, 0.99)

0.92 (⫺0.33, 0.89) 0.90 (⫺0.57, 2.38) 0.65 (0.03, 1.27) 0.50 (⫺0.11, 1.11) 0.24 (⫺0.37, 0.85) 0.26 (⫺0.35, 0.87)

Note. Data are effect sizes with 95% confidence intervals shown below in parentheses. IE ⫽ imaginal exposure; IV ⫽ in vivo exposure; CR ⫽ cognitive restructuring; CAPS ⫽ Clinician-Administered PTSD Scale; IES ⫽ Impact of Event Scale; STAI ⫽ State–Trait Anxiety Inventory (State Scale); BDI ⫽ Beck Depression Inventory; CCQ ⫽ Catastrophic Cognitions Questionnaire.

pants in the IV and IE/IV groups tended to display small to moderate effect sizes relative to those in the IE group. In terms of high end-state functioning, more participants in the IE/IVE/CR condition (36%) achieved high end-state functioning than did participants in the IE (10%), IVE (18%), or IE/IVE (16%) conditions, ␹2(1, N ⫽ 118) ⫽ 6.87, p ⬍ .05. More participants in IE/IVE/CR (75%) achieved clinically significant change than did those in IE/IVE (42%), IE (42%), and IVE (29%) conditions, ␹2(1, N ⫽ 118) ⫽ 13.27, p ⬍ .005.

Completer Analyses Primary outcome measure. Table 4 presents the mean psychopathology scores for the completer sample. The ANCOVA on posttreatment responses indicated a main effect for CAPS, F(3, 85) ⫽ 4.37, p ⬍ .01. Post hoc Tukey comparisons indicated that IE/IVE/CR participants scored lower than did IE ( p ⬍ .005), IV ( p ⬍ .001), and IE/IV ( p ⬍ .05) participants on CAPS scores ( p ⬍ .05). In terms of follow-up analyses, the ANCOVA indicated a main effect for CAPS, F(3, 79) ⫽ 3.09, p ⬍ .05. Post hoc Tukey comparisons indicated that IE/IVE/CR participants scored lower than did IE ( p ⬍ .005), IV ( p ⬍ .001), and IE/IV ( p ⬍ .05) participants on CAPS scores ( p ⬍ .05). At posttreatment there were marginally fewer participants in the IE/IVE/CR condition (21%) with PTSD than in the IE (52%), IVE (55%), and IE/IVE (48%) conditions, ␹2(1, N ⫽ 90) ⫽ 6.96, p ⫽ .07. At follow-up,

there were fewer participants with PTSD in the IE/IVE/CR (14%) than the IE (43%), IVE (62%), and IE/IVE (43%) groups, ␹2(1, N ⫽ 84) ⫽ 10.08, p ⬍ .05. Secondary measures. In terms of secondary measures, separate ANCOVAs on posttreatment measures indicated no main effects. At follow-up, ANCOVAs indicated significant effects for IES–Intrusions, F(3, 79) ⫽ 3.30, p ⬍ .05, and IES–Avoidance, F(3, 79) ⫽ 2.61, p ⬍ .05. Post hoc Tukey comparisons indicated that IE/IVE/CR participants scored lower than did IE ( p ⬍ .01), IV ( p ⬍ .05), and IE/IV ( p ⬍ .01) participants on the IES–Intrusions scale. Similarly, IE/IVE/CR participants scored lower than did IE ( p ⬍ .01), IV ( p ⬍ .05), and IE/IV ( p ⬍ .05) participants on the IES–Avoidance scale. Table 3 also presents the between-groups effect sizes for posttreatment and follow-up measures. The pattern of findings was comparable to the intent-to-treat analyses in that participants in the IE/IVE/CR condition displayed larger effect sizes on most measures than did the participants in other conditions. Although there were no significant differences between groups in terms of proportions achieving high end-state functioning, approximately twice as many participants in the IE/IVE/CR condition (46%) achieved high end-state functioning than participants in the IE (14%), IVE (24%), or IE/IVE (24%) conditions, ␹2(1, N ⫽ 84) ⫽ 5.73, p ⫽ .12. More participants in IE/IVE/CR (90%) achieved clinically significant change than

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Table 4 Psychopathology Measures for Completer Analyses Outcome measure

Imaginal exposure


45.35 (32.83) 17.83 (8.47) 16.87 (10.84) 47.13 (16.76) 18.57 (13.62) 67.90 (21.39)


46.81 (29.10) 17.76 (10.69) 17.38 (9.53) 53.71 (17.90) 15.67 (11.27) 59.11 (22.94)



Posttreatment 49.55 (23.28) 15.18 (10.87) 15.77 (11.75) 48.91 (18.00) 18.59 (11.48) 67.48 (20.26)

36.95 (30.57) 15.29 (12.04) 16.19 (12.86) 42.05 (15.66) 15.00 (12.26) 54.53 (17.46)

21.71 (18.42) 11.96 (9.68) 11.83 (11.25) 43.42 (16.11) 12.71 (11.56) 56.58 (20.34)

Follow-up 52.53 (30.92) 17.43 (12.52) 16.48 (11.28) 49.71 (17.41) 19.05 (13.26) 70.15 (14.57)

38.43 (28.60) 18.62 (11.87) 18.29 (11.86) 50.86 (15.42) 18.90 (13.39) 51.55 (14.82)

23.71 (19.46) 9.29 (8.93) 10.14 (12.07) 42.43 (25.65) 11.95 (11.93) 53.36 (20.58)

In vivo exposure

Note. Data are means (standard deviations). CAPS ⫽ Clinician-Administered PTSD Scale; IES ⫽ Impact of Event Scale; STAI ⫽ State–Trait Anxiety Inventory (State Scale); BDI ⫽ Beck Depression Inventory; CCQ ⫽ Catastrophic Cognitions Questionnaire.

did those in the IE/IVE (62%), IE (62%), and IVE (38%) conditions, ␹2(1, N ⫽ 84) ⫽ 12.42, p ⬍ .01.

Incidence of Relapse To determine the rate of relapse between posttreatment and follow-up assessments between treatment conditions, we defined relapse as an increase in symptoms of ⱖ15.48 on the CAPS (see Devilly & Foa, 2001, for a discussion on calculation of this figure). There was no significant difference between rates of relapse between IE (28.6%), IVE (14.3%), IE/IV (14.3%), and IE/IVE/CR (9.5%), ␹2(1, N ⫽ 84) ⫽ 3.09, p ⫽ .38, although there was a trend for IE participants to relapse more than those in the other conditions.

Discussion The major finding of this study was that combining IE, IVE, and CR resulted in greater treatment effects for both PTSD and depressive symptoms than did exposure alone. Although expected, this finding contrasts with previous evidence that CR does not provide additive gains relative to those provided by exposure in the treatment of PTSD (Foa et al., 2005; Marks et al., 1998; Paunovic & Ost, 2001). There are several possible reasons we found that CR increased the treatment response when added to exposure. First, we carefully matched the therapy time devoted to each therapy component. In this way, we ensured that participants receiving CR also received the same amount of exposure provided to participants in the exposure conditions. This explanation is not supported, however, by evidence that shorter doses of exposure (30 min) are as effective in reducing PTSD symptoms as longer (60 min) sessions (van Minnen & Foa, 2006). Second, it is possible that we achieved a superior effect of combining CR to exposure because our exposure protocols were not as effective as many previously reported in the literature. For example, Foa, Riggs, Dancu, and Rothbaum (1993) reported effect sizes for intent-totreat analyses of 1.37 on the PTSD Symptom Scale for IE/IVE and 1.30 for IE/IVE/CR. In contrast, our study reported effect sizes of

0.84 on the CAPS for IE/IVE and 1.52 for IE/IVE/CR. There are several possible explanations for this discrepancy. The design of the study resulted in exposure being delivered in a way that was possibly different from previous treatment studies. Many exposure protocols explicitly suggest discussion of the exposure experience that potentially includes CR components. For example, Riggs, Cahill, and Foa (2006) suggested that “following the recounting, the therapist and patient spend time discussing the patient’s reactions to the exposure exercise, with particular emphasis on thoughts and emotions that arose during the recounting” (p. 67). The current study attempted to achieve integrity of the design by precluding structured CR in the exposure sessions and allowed the therapist only to discuss the exposure experience without directly suggesting to participants how they could be modifying their thoughts. We recognize that this procedure may have resulted in reduced therapeutic gain by the exposure because we may not have engaged in the degree of cognitive reframing after exposure that previous studies may have done. This restriction may have limited the benefit of exposure relative to how it has been administered in previous trials. Despite the apparent discrepancies, we note that the rates of PTSD diagnosis after treatment in the present study are comparable to those in many other trials of CBT for PTSD (Bradley et al., 2005). Despite the discrepancies with previous studies, there is a need to explain the greater effect of therapy when CR was combined with exposure in the current study. The proposed mechanism underpinning CR is that it identifies and corrects maladaptive thoughts that contribute to PTSD (Beck et al., 1985). It is possible that CR extended the gains made by exposure because it served to correct maladaptive cognitions more effectively than did exposure therapy. This interpretation is supported by the finding that IE/ IVE/CR led to greater reductions on the CCQ than did the other conditions. This interpretation would have been strengthened if we had included a measure to specifically index trauma-related cognitions, such as the Posttraumatic Cognitions Inventory (Foa, Ehlers, Clark, Tolin, & Orsillo, 1999). Regrettably, that measure was not available at the time this study commenced. This inter-

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pretation is not supported by evidence that exposure leads to cognitive change without formal CR (Foa & Rauch, 2004; Paunovic & Ost, 2001). Alternately, it is possible that the CR and exposure-based therapies share common therapeutic mechanisms, such as processing of emotional memories, integration of corrective information, and development of self-mastery (Marks, 2000). This possibility is suggested by evidence that exposure therapy alone results in changes in maladaptive appraisals related to the traumatic experience (Foa & Rauch, 2004). It is possible that adding CR to exposure helps participants engage in these processes to a greater extent than patients who received only exposure. A further possibility is that providing CR may have assisted patients to utilize the exposure components of therapy more effectively, leading to greater treatment response. The finding that IE, IVE, and the combination of these interventions did not lead to different outcomes is somewhat surprising. The only previous study to compare IE and IVE found that IVE was more effective than IE in reducing avoidance, presumably because IVE directly targets phobic avoidance behaviors (Richards et al., 1994). That study was uncontrolled, however. The current results suggest that IE and IVE performed comparably. It is possible that both forms of exposure may involve similar mechanisms: By safely confronting either trauma memories or situational reminders the patient achieves comparable reductions in PTSD. This finding accords with information processing models of PTSD, which posit that repeated exposures to feared stimuli facilitate emotional processing of affective information and that this can be achieved by imaginal or in vivo forms of exposure (Foa & HearstIkeda, 1996). There has been limited study into differential responses to IE and IVE, and although comparable change mechanisms are presumed, there is a need for experimental study to determine whether common mechanisms do underpin both forms of exposure. The combined treatment condition resulted in greater reductions in depression than any of the other treatments. Several explanations may be offered for this pattern. First, the depressive symptoms may be secondary to, and a result of, experiencing PTSD (Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995), in which case the greater PTSD reduction in the IE/IVE/CR condition would explain the greater reductions in depressive symptoms. Second, CR was initially developed to reduce depression by modifying overly negative cognitions that maintain depressed mood (Beck, Rush, Shaw, & Emery, 1979). Consistent with this goal, there is much evidence that CR can reduce depression (Hollon, Thase, & Markowitz, 2002). Adding CR to exposure components may have directly resulted in correction of depressogenic thinking and, accordingly, the combined treatment condition may have reduced depression by alleviating negative thoughts. We note several limitations to the study. First, the sample size was modest for a design that incorporated four treatments with proven efficacy; a larger sample may have revealed more differences between treatment groups. Second, we did not index the extent to which assessors were blind to participants’ treatment condition by obtaining judgments from assessors concerning their beliefs about participants’ treatment condition. Third, we recognize that limiting exposure to IVE with some patients can be difficult because they may have limited situational reminders. Fourth, we reiterate that we imposed a clear delineation between exposure and CR, and this may have limited the comparability of

these findings to other studies and to common clinical practice. Fifth, we did not assess for comorbid disorders through structured clinical interview, and so we cannot make inferences concerning the role of comorbidity on treatment outcomes. These data provide preliminary evidence that CR provides additive gains to those provided by exposure in treating PTSD. Although previous evidence has suggested that providing CR may not be necessary in the treatment of PTSD (Foa et al., 2005; Marks et al., 1998; Paunovic & Ost, 2001), the current results suggest that therapists should consider implementing cognitive restructuring techniques in conjunction with exposure-based therapies. We note that many exposure protocols do explicitly incorporate cognitive reframing in the context of their exposure, and the current findings underscore the worth of ensuring that maladaptive appraisals are addressed in the course of exposure therapy. We also note that it is arguably easier to train clinicians in exposure therapy than in CR, which requires intensive and repeated training and supervision. In contrast, exposure practices can often be taught in a reasonably brief period of time, and this factor may facilitate dissemination of exposure as a potent component of CBT to clinicians in the community.

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Received June 26, 2007 Revision received March 27, 2008 Accepted April 1, 2008 䡲