A Randomized Clinical Trial Comparing an Acceptance-Based BehaviorTherapy to Applied Relaxation for Generalized Anxiety Disorder

Sarah A. Hayes-Skelton and Lizabeth RoemerUniversity of Massachusetts Boston

Susan M. OrsilloSuffolk University

Objective: To examine whether an empirically and theoretically derived treatment combiningmindfulness- and acceptance-based strategies with behavioral approaches would improve outcomes ingeneralized anxiety disorder (GAD) over an empirically supported treatment. Method: This trialrandomized 81 individuals (65.4% female, 80.2% identified as White, average age 32.92) diagnosed withGAD to receive 16 sessions of either an acceptance-based behavior therapy (ABBT) or applied relaxation(AR). Assessments at pretreatment, posttreatment, and 6-month follow-up included the followingprimary outcome measures: GAD clinician severity rating, Structured Interview Guide for the HamiltonAnxiety Rating Scale, Penn State Worry Questionnaire, Depression Anxiety Stress Scale, and theState–Trait Anxiety Inventory. Secondary outcomes included the Beck Depression Inventory—II, Qual-ity of Life Inventory, and number of comorbid diagnoses. Results: Mixed effect regression modelsshowed significant, large effects for time for all primary outcome measures (ds � 1.27 to 1.61) butnonsignificant, small effects for condition and Condition � Time (ds � 0.002 to 0.20), indicating thatclients in the 2 treatments improved comparably over treatment. For secondary outcomes, time wassignificant (ds � 0.74 to 1.38), but condition and Condition � Time effects were not (ds � 0.004 to0.31). No significant differences emerged over follow-up (ds � 0.03 to 0.39), indicating maintenance ofgains. Between 63.3 and 80.0% of clients in ABBT and 60.6 and 78.8% of clients in AR experiencedclinically significant change across 5 calculations of change at posttreatment and follow-up. Conclusion:ABBT is a viable alternative for treating GAD.

Keywords: acceptance-based treatment, behavior therapy, mindfulness, acceptance

Generalized anxiety disorder (GAD) is a chronic anxiety disor-der associated with high comorbidity (Bruce, Machan, Dyck, &Keller, 2001), reduced quality of life (Hoffman, Dukes, &

Wittchen, 2008), and significant health care utilization (Hoffmanet al., 2008). Meta-analyses reveal that cognitive behavioral ther-apies are efficacious for GAD (Borkovec & Ruscio, 2001; Covin,Ouimet, Seeds, & Dozois, 2008). However, GAD remains one ofthe least successfully treated of the anxiety disorders (Waters &Craske, 2005), with most studies finding that less than 65% ofclients meet criteria for high end-state functioning at posttreatment(e.g., Ladouceur et al., 2000; Newman et al., 2011) and few studiesexamining the impact of treatment on quality of life.

Several researchers have aimed to refine and expand existingmodels of GAD in an effort to more clearly identify causal andmaintaining factors to target in therapy (see Behar, DiMarco,Hekler, Mohlman, & Staples, 2009, for a review). Recent random-ized controlled trials (RCTs) informed by these models indicatethat targeting intolerance of uncertainty (Dugas et al., 2010) andthe interpersonal and emotion-focused aspects of GAD (Newmanet al., 2011) yield effects comparable to existing cognitive behav-ioral therapies for GAD. A small pilot study found that targetingmeta-cognition in GAD (Wells et al., 2010) produced better out-comes than applied relaxation; however, the very low rates ofresponse to applied relaxation, coupled with the small sample size,indicate a need for further research to confirm this finding.

Roemer and Orsillo (2002) developed a model of GAD in-formed by research and theory highlighting the potential roles ofexperiential avoidance (e.g., Hayes, Wilson, Gifford, Follette, &Strosahl, 1996) and ruminative, self-critical processing (e.g., Bar-nard & Teasdale, 1991) in the development and maintenance of

This article was published Online First May 6, 2013.Sarah A. Hayes-Skelton and Lizabeth Roemer, Department of Psychol-

ogy, University of Massachusetts Boston; Susan M. Orsillo, Department ofPsychology, Suffolk University.

This work was supported by National Institute of Mental Health GrantsMH074589, awarded to the second and third authors, and MH085060,awarded to the first author. We thank the large team that made this projectpossible. Tom Borkovec and Zindel Segal provided training to therapists. TomBorkovec also completed competency ratings of applied relaxation therapists.Tim Brown managed the assessment team. Therapists included StephanieCzech Berube, Shannon Erisman, Cara Fuchs, Jonathan Lee, Kara Lustig,Heather Murray, Kathleen Sullivan, Kalill Michael Treanor, Aisha Usmani,Lindsey West, and the first author. Assessors included Cathryn Freid, CassidyGutner, Aaron Kaiser, Ovsanna Leyfer, Joseph Meyer, Michael Moore, andAnthony Rosellini. Additionally, we thank the following for their help withdata management and adherence ratings: Stephanie Czech Berube, ShannonErisman, Elizabeth Eustis, Cara Fuchs, Jessica Graham, Aviva Katz, SarahKrill, Heidi Barrett Model, Lucas Morgan, Dan Paulus, Estie Reidler, MichaelTreanor, and Lindsey West, as well as numerous University of MassachusettsBoston undergraduate students. Finally, we would like to thank the clients. Thiswork would not be possible without their openness, courage, and willingness.

Correspondence concerning this article should be addressed to Sarah A.Hayes-Skelton, University of Massachusetts Boston, Department of Psy-chology, 100 Morrissey Boulevard, Boston, MA 02125. E-mail:sarah.hayes@umb.edu

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Journal of Consulting and Clinical Psychology © 2013 American Psychological Association2013, Vol. 81, No. 5, 761–773 0022-006X/13/$12.00 DOI: 10.1037/a0032871

761

psychopathology. Supported by research comparing individualswith and without GAD, this model suggests that those with GADhave a problematic relationship with their internalized experiencescharacterized by a narrowed attention toward threat (Bar-Haim,Lamy, Pergamin, Bakermans-Kranenburg, & van IJzendoorn,2007) and a critical, judgmental reactivity toward their emotionalresponses (e.g., Lee, Orsillo, Roemer, & Allen, 2010; Llera &Newman, 2010; Mennin, Heimberg, Turk, & Fresco, 2005) andthoughts (Wells & Carter, 1999). This reaction to internal experi-ences motivates individuals with GAD to engage in experientialavoidance (e.g., Lee et al., 2010) using a variety of strategiesincluding worry, the central defining feature of GAD. Althoughworry decreases somatic arousal and helps to distract an individualfrom more emotional topics (see Borkovec, Alcaine, & Behar,2004, for a review), rigid habitual efforts at experiential avoidancecan paradoxically increase distress (e.g., Hayes et al., 1996),leading to a cycle of reactivity and avoidance that in turn affectsbehavior. Individuals with GAD are less likely to consistentlyengage in behaviors that are important to them (i.e., valued ac-tions) and as a result experience a diminished quality of life(Michelson, Lee, Orsillo, & Roemer, 2011).

This model led to the development of an acceptance-basedbehavior therapy for GAD (ABBT; Roemer & Orsillo, 2009, inpress), a flexible treatment adapted from traditional cognitivebehavioral therapy (CBT) for GAD (e.g., Borkovec et al., 2004) aswell as from other acceptance-based behavioral therapies. Thelatter group includes acceptance and commitment therapy (ACT;Hayes, Strosahl, & Wilson, 1999), mindfulness-based cognitivetherapy (MBCT; Segal, Williams, & Teasdale, 2002), and dialec-tical behavior therapy (Linehan, 1993), which explicitly targetthese mechanisms.1 In particular, this ABBT aims to help clients tocultivate an expanded (as opposed to narrowed, threat-focused)awareness along with a compassionate (as opposed to judgmental)and decentered (as opposed to seeing thoughts and feelings asall-encompassing indicators of truth) stance toward internal expe-riences. These new skills reduce rigid experiential avoidance, asdoes the explicit promotion of an accepting and willing stancetoward internal experiences. Behavioral avoidance and constric-tion are targeted by encouraging clients to identify and mindfullyengage in personally meaningful actions. ABBT uses empathicvalidation, self-monitoring, formal and informal mindfulness ex-ercises, encouragement of acceptance through psychoeducationand experiential exercises, and writing and behavioral exercisesthat apply these skills to personally meaningful activities (seeRoemer & Orsillo, 2009, in press, for a more detailed presentationof the treatment).

Data from an open trial (Roemer & Orsillo, 2007) and waitlistRCT (Roemer, Orsillo, & Salters-Pedneault, 2008) indicate signif-icant effects on clinician-rated and self-report symptom measuresof anxiety and depression, as well as self-reported quality of lifeand high rates of end-state functioning. Clients receiving ABBTreport significant decreases in experiential avoidance (Roemer etal., 2008), distress about emotional responses, and intolerance ofuncertainty (Treanor, Erisman, Salters-Pedneault, Roemer, & Or-sillo, 2011) and significant increases in values-consistent behavior(Michelson et al., 2011). Moreover, both the time spent acceptinginternal experiences and that spent engaging in valued activitiessignificantly predict outcome (Hayes, Orsillo, & Roemer, 2010),providing support for the proposed mechanisms of action. How-

ever, studies are needed that compare this treatment to a credible,efficacious alternative therapy.

Other acceptance- and mindfulness-based treatments have beentested for GAD. A recent study comparing ACT to CBT (withbehavioral exposures in both conditions) showed comparable ef-fects of the two treatments, with the 14 individuals with GAD whoreceived ACT demonstrating medium to large effects on outcomemeasures (Arch et al., 2012). Similarly, in a study of older adultswith GAD, the seven individuals receiving ACT demonstratedlarge effect sizes on outcome measures, which were comparable tothose for the nine individuals receiving CBT in this study (Weth-erell et al., 2011). A recent meta-analysis demonstrated the prom-ise of mindfulness-based interventions in reducing anxiety gener-ally (Hofmann, Sawyer, Witt, & Oh, 2010), and two preliminarytrials of MBCT suggest an effect of treatment on self-reportedGAD symptoms (Craigie, Rees, Marsh, & Nathan, 2008; Evans etal., 2008), although outcomes fell short relative to other GADtreatment trials. Unlike ACT and ABBT, MBCT did not incorpo-rate behavioral strategies, which may partly explain the moremodest effects.

Although findings for ABBT are promising, previous studieswere limited by absence of an active control condition and modestsample sizes. To more rigorously test ABBT, this study comparedABBT to an established and efficacious treatment, applied relax-ation (AR). AR is an empirically supported treatment for GAD(Chambless & Ollendick, 2001) and is recommended in the NICEClinical Guideline 113 (National Collaborating Centre for MentalHealth and the National Collaborating Centre for Primary Care,2011). This status comes from several methodologically rigorousstudies that have examined the efficacy of AR. For example,randomized controlled trials demonstrated that AR was more ef-ficacious than a nondirective, reflective listening therapy (Bork-ovec & Costello, 1993) and roughly as efficacious as cognitivetherapy (Arntz, 2003; Öst & Breitholtz, 2000), cognitive behav-ioral therapy (Borkovec & Costello, 1993; Dugas et al., 2010), andworry exposure (Hoyer et al., 2009) in treating GAD. Furthersupporting the efficacy of AR, a meta-analysis by Siev andChambless (2007) found that cognitive therapy and relaxationtherapy were equivalent treatments for GAD. AR is also straight-forward and relatively easy to learn, which increases the probabil-ity that therapists can deliver it with good adherence and compe-tence.

In the spirit of a comparative efficacy trial, we hypothesized thatboth ABBT and AR would lead to statistically and clinicallysignificant change but that ABBT would be more efficacious thanAR on measures of anxiety and quality of life. Additionally,because the processes targeted in ABBT are presumed to underliemany forms of psychopathology, we hypothesized that ABBTwould be associated with greater decreases in depression andcomorbidity than would AR. Finally, we hypothesized that thetreatments would be comparably credible and acceptable to par-ticipants.

1 This specific ABBT is thus part of a larger class of acceptance-basedbehavioral therapies, developed to target GAD and related symptoms,similar to a particular CBT protocol for a target condition being part of alarger class of cognitive behavioral therapies (Roemer & Orsillo, 2009).

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762 HAYES-SKELTON, ROEMER, AND ORSILLO

Method

Participants

The majority of participants were recruited from treatment-seeking individuals at the Center for Anxiety and Related Disor-ders at Boston University between 2007 and 2010. Potential par-ticipants were referred to this study if they received a principaldiagnosis of GAD on an intake diagnostic interview (AnxietyDisorders Interview Schedule for DSM–IV; ADIS-IV, Di Nardo,Brown, & Barlow, 1994). In addition, two participants were re-ferred after being ruled out of a study for panic disorder treatmentdue to a principal diagnosis of GAD, and five participants weredirectly referred to the study from practitioners in the community.Participants were eligible for this study if they (a) received aprincipal diagnosis of GAD on the ADIS-IV with at least moderateseverity (4) on the clinician severity rating; (b) reported a GADonset that preceded their first episode of major depressive disorder;(c) were stable on any medications for 3 months and were willingto maintain current psychotropic medication levels and to refrainfrom other psychosocial treatments for anxiety or mood problemsduring the course of therapy; (d) were fluent in English; and (e)were 18 years or older. Exclusion criteria were due to clinicalconsiderations: diagnoses of comorbid bipolar disorder, a psy-chotic disorder, an autism-spectrum disorder, or current substancedependence. Eligibility was primarily assessed by an independentassessor (IA) who conducted the diagnostic assessment. However,inclusion and exclusion criteria were confirmed by a study thera-pist.

The participant flowchart (see Figure 1) shows the number ofparticipants at each stage. One hundred and twenty participantswere contacted for a phone screen following their initial assess-ment to further determine eligibility and interest in the study.Eighty-five participants met eligibility by IA interview, but fourwere excluded by the therapist, in consultation with the supervi-sors, because they did not meet criteria (2 were not stable onmedications and 2 did not have GAD as a principal diagnosis).Thus, 81 participants met inclusion/exclusion criteria, consented tothe study, and were randomized. Of the 81 participants, 63 wereconsidered treatment completers.2 A research assistant determinedthe treatment assignment by randomly allocating conditions toparticipant identification numbers using a random integer genera-tor while forcing even distribution in each block of eight partici-pants at the commencement of the study. Slips of paper linking IDnumbers and conditions were then concealed from all study staff;the therapist drew the appropriate slip after participant consent. Ofthe participants, 40 were randomized to ABBT and 41 to AR. Asshown in Table 1, there were no significant differences betweenconditions on demographic variables, psychotropic medication,previous therapy, or the presence of comorbid diagnoses.

Primary Outcome Measures

ADIS-IV (Di Nardo et al., 1994) is a semistructured diagnosticinterview used to determine current and lifetime Diagnostic andStatistical Manual of Mental Disorders (DSM–IV; American Psy-chiatric Association, 1994) diagnostic status. For GAD, theADIS-IV has demonstrated adequate reliability (� � .67; Brown,Di Nardo, Lehmann, & Campbell, 2001). Independent assessors

gave the ADIS-IV-L (lifetime version) at pretreatment and theADIS-IV (current) at the posttreatment and follow-up assessments.Both versions include a clinician’s severity rating (CSR; rangingfrom 0 to 8, with 4 or greater clinically significant) for eachdiagnosis received. Independent assessors were postdoctoral fel-lows or graduate students, unaware of treatment condition, trainedin the administration and scoring of the ADIS.3 Diagnoses wereconfirmed in a consensus meeting with a doctoral-level psychol-ogist (Tim Brown) and by therapists. Additionally, 30% of inter-views were scored by a second rater, with an interclass correlation(ICC) between raters on CSR for GAD of .73.

Structured Interview Guide for the Hamilton Anxiety RatingScale (SIGH-A; Shear et al., 2001) provides a reliable, validstructured format for administering the Hamilton Anxiety RatingScale (HARS; Hamilton, 1959), a widely used 14-iteminterviewer-administered measure of anxiety. In this sample, in-ternal consistencies were .76 at pre and .82 at both post andfollow-up. Postdoctoral fellows or doctoral students, after training,administered the measure, and 15% were rated twice for interaterreliability, revealing an ICC of .89.

Penn State Worry Questionnaire (PSWQ; Meyer, Miller,Metzger, & Borkovec, 1990) is a widely used, reliable, valid16-item self-report measure of trait levels of worry. In this sample,the internal consistencies were .82 at pre, .90 at post, and .92 atfollow-up.

Depression Anxiety Stress Scale–21-item version (DASS-21;Lovibond & Lovibond, 1995) has separate, reliable, and validself-report scales for depression, anxiety (i.e., anxious arousal),and stress (i.e., general anxiety and tension; Antony, Bieling, Cox,Enns, & Swinson, 1998). We used the Stress subscale as anoutcome measure because it discriminates between clients withGAD and those with panic disorder, social phobia, and specificphobia (Brown, Chorpita, Korotitsch, & Barlow, 1997). The Stresssubscale had internal consistencies of .80 at pre, .88 at post, and.85 at follow-up. Scores were doubled to be comparable to the42-item version.

State–Trait Anxiety Inventory—Trait Form Y (STAI; Spiel-berger, Gorsuch, Lushene, Vagg, & Jacobs, 1983) is a reliable,valid 20-item self-report measure that assesses trait levels ofanxiety. Internal consistencies were .88 at pre, .95 at post, and .94at follow-up.

2 Treatment completers were those clients who completed at least 13 ofthe 16 sessions. This includes five clients who completed 14–15 sessionsinstead of the full 16. Four of these five clients had planned early endingsbecause either the client (n � 2) or the therapist (n � 2) was moving fromthe area. The reason the fifth client ended early was unknown. Addition-ally, one client in AR felt that she had improved by Session 2 and agreedto an abbreviated 8-week course of treatment. The reasons that individualsdropped out of therapy before Session 13 are included in Figure 1.

3 As described in Brown et al. (2001), all assessors underwent extensivetraining before administering the ADIS. Initial training included readingthe manual, observing interviewers, and administering interviews in col-laboration with a certified interviewer. Then, to be certified, assessorsneeded to match a senior interviewer’s diagnoses on three of five consec-utive interviews. A match was defined as agreement on the principaldiagnosis and agreement within 1 point on the CSR as well as theidentification of all additional clinically significant disorders.

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763ACCEPTANCE-BASED BEHAVIOR THERAPY VS. APPLIED RELAXATION

Secondary Outcome Measures

Beck Depression Inventory—II (BDI–II; Beck, Steer, & Brown,1996) is a 21-item self-report measure assessing current levels ofdepression. In this sample, the internal consistencies were .91 atpre, .95 at post, and .95 at follow-up.

Quality of Life Inventory (QOLI; Frisch, Cornwell, Villanueva,& Retzlaff, 1992) is a 32-item self-report measure assessing thedegree of importance and level of satisfaction with each of 16areas of life. Internal consistencies were .80 at pre and .86 at postand follow-up in this sample.

Treatment Process Measures

Credibility/Expectation Scales (Borkovec & Nau, 1972) wasgiven at the end of the first session.

Working Alliance Inventory—Short (WAI-S; Tracey & Koko-tovic, 1989) is a reliable, valid 12-item measure of client andtherapist perceptions of the agreement in the goals and tasks oftherapy as well as the therapeutic bond. It was given after Session4 in this study. The internal consistencies were .92 for clients and.91 for therapists.

Reaction to treatment. During the posttreatment assessment,clients used a 9-point Likert scale to rate the extent to which thetreatment was a good match to them.

Procedures

All study procedures were approved by the Boston University,University of Massachusetts Boston, and Suffolk University Inter-nal Review Boards as well as by a data safety and monitoring

board. All participants provided informed consent for the study.Participants were enrolled in this study following completion ofthe ADIS and a phone screen to determine eligibility. Participantsreceived therapy free of charge and were paid $50 each forcompleting posttreatment and 6-month follow-up assessments.

Interventions

Both treatments were 16 sessions in length, with four initialweekly 90-min sessions followed by weekly 60-min sessions anda biweekly taper between Sessions 14, 15, and 16. Prior to Session1, therapists met with clients to learn more about the client’sunderstanding of her or his worry and anxiety, to assess contextualfactors that might affect the client’s symptoms and course oftherapy (e.g., urgent financial, housing or family issues), to brieflyexplore the client’s cultural identity, to assess previous medicationand therapy experiences, to address any potential obstacles totreatment, and to instill hope.

Acceptance-based behavioral therapy (ABBT; Orsillo & Ro-emer, 2011; Roemer & Orsillo, 2009). As described above,ABBT focuses on modifying problematic relationships with one’sinternal experiences, while decreasing experiential avoidance andbehavioral constriction. Each session begins with a mindfulnessexercise and a review of between session assignments, followed bythe session-specific content, and ends with the assignment ofbetween-session activities. A specific progression of mindfulnesspractices is used to help clients develop basic skills (e.g., observingbreath during a sitting meditation) before moving toward theapplication of these skills in challenging contexts (e.g., observingpainful thoughts and emotions during a conflict).

Figure 1. Participant flow through the study. GAD � generalized anxiety disorder.

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764 HAYES-SKELTON, ROEMER, AND ORSILLO

ABBT has two distinct phases of treatment. The first phase(roughly Sessions 1–7) introduces clients to an acceptance-basedbehavioral model of anxiety. The sessions focus on the function ofanxiety and emotions: more broadly, the ways that emotions canbecome intensified or “muddy”; the costs of trying to avoid orcontrol internal experiences; and the potential benefit of taking anaccepting, willing, and decentered stance and committing to mak-ing decisions based on values rather than avoiding anxiety. Clientsare also introduced to mindfulness and gradually practice buildingmindfulness skills. Finally, a series of values-based writing exer-cises is used to help clients articulate what they value aboutrelationships, work and school, and self-care and community en-gagement and eventually commit to taking mindful actions in theseareas.

Sessions in the second phase (roughly Sessions 8–16) focus onapplying the mindfulness and acceptance skills developed in thefirst phase of therapy as the client pursues valued life directions

each week. As obstacles arise (e.g., client reverts to control andavoidance strategies to cope with anxiety), the client and therapistreturn to concepts introduced earlier in treatment (e.g., attempts tocontrol and avoid intensify anxiety, it is possible to experienceanxiety and still pursue valued actions). In Sessions 14 through 16,clients review the changes they have made, consider strategies thatwere most effective, and plan for ways to maintain gains aftertermination.

Applied relaxation (AR; Bernstein, Borkovec, & Hazlett-Stevens, 2000; Öst, 2007). AR focuses on developing relaxationskills primarily through diaphragmatic breathing and progressivemuscle relaxation (PMR; moving from 16 muscle groups graduallyto a rapid relaxation that can be applied in daily life); enhancingawareness of early signs of anxiety; and finally applying a briefrelaxation exercise in response to early signs of anxiety. Ourmanual (reviewed by T. D. Borkovec) was derived from Bernsteinet al. (2000) and Lars Öst’s treatment and was expanded to 16

Table 1Demographic Characteristics of the Sample

Characteristic ABBT (n � 40) AR (n � 41) �2 or F p

Age M (SD) 33.30 (12.42) 32.56 (12.05) 0.07 .79Gender 1.03 .31

Women 60.0% (n � 24) 70.7% (n � 29)Men 40.0% (n � 16) 29.3% (n � 12)

Race/ethnicity 0.38 .54White 77.5% (n � 31) 82.9% (n � 34)Hispanic/Latino(a) 10.0% (n � 4) 7.3% (n � 3)Asian 2.5% (n � 1) 7.3% (n � 3)Black 5.0% (n � 2) 2.4% (n � 1)Middle Eastern 2.5% (n � 1) 0.0% (n � 0)Biracial (Asian and White) 2.5% (n � 1) 0.0% (n � 0)

Previous psychotherapy 0.002 .97Yes 85.0% (n � 34) 85.4% (n � 35)No 15.0% (n � 6) 14.6% (n � 6)

Previous CBT/skills-based therapy 0.004 .95Yes 22.5% (n � 9) 22.0% (n � 9)No 75.0% (n � 30) 75.6% (n � 31)

Taking psychotropic medication 2.51 .28Yes 22.5% (n � 9) 34.1% (n � 14)No 77.5% (n � 31) 63.4% (n � 26)SSRI 10.0% (n � 4) 22.0% (n � 9)Benzodiazepines 15.0% (n � 6) 4.9% (n � 2)TCA 2.5% (n � 1) 4.9% (n � 2)Othera 5.0% (n � 2) 4.9% (n � 2)

Additional diagnoses 1.63 .20Yes 62.5% (n � 25) 75.6% (n � 31)No 37.5% (n � 15) 24.4% (n � 10)Social anxiety 42.5% (n � 17) 48.8% (n � 20)Major depression 7.5% (n � 3) 17.1% (n � 7)Panic disorder w/ag 7.5% (n � 3) 17.1% (n � 7)Specific phobia 10.0% (n � 4) 4.9% (n � 2)Eating disorder NOS 2.5% (n � 1) 12.2% (n � 5)OCD 5.0% (n � 2) 0.0% (n � 0)PTSD 2.5% (n � 1) 2.4% (n � 1)Otherb 12.5% (n � 5) 2.4% (n � 1)

Note. Age is in years. Given the small sample size of individual groups, Race/ethnicity compared those whodid and did not identify as White across treatments. ABBT � acceptance-based behavior therapy; AR � appliedrelaxation; CBT � cognitive behavioral therapy; SSRI � selective serotonin reuptake inhibitor; TCA � tricyclicantidepressant; w/ag � with agoraphobia; NOS � not otherwise specified; OCD � obsessive-compulsivedisorder; PTSD � posttraumatic stress disorder.a Other medications � serotonin and norepinephrine reuptake inhibitor (SNRI), buspar, trazadone, and pro-panalol. b Other additional diagnoses � dysthymia, panic disorder without agoraphobia, depressive disorderNOS, attention-deficit/hyperactivity disorder, impulse control NOS, and sexual disorder NOS.

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765ACCEPTANCE-BASED BEHAVIOR THERAPY VS. APPLIED RELAXATION

sessions to match ABBT. Each therapy session began with adiaphragmatic breathing or brief relaxation exercise, followed by areview of between-session assignments, and ended with the as-signment of between-session activities. In the first half of AR(roughly Sessions 1–8), the focus is on building relaxation skillsand developing an awareness of client-specific early signs ofanxiety. Clients began with a 16-muscle group PMR that wasdecreased to 8 and then 4 muscle groups once clients were able toachieve relaxation with the longer exercise. The second phase oftherapy (roughly Sessions 8–16) focuses on applying relaxation toearly signs of anxiety both in session and between session. Clientsare taught release-only, cue-controlled, differential, and rapid re-laxation with an added focus on application skills. The last threesessions highlight relapse prevention and strategies for maintain-ing gains.

Therapists

Postdoctoral fellows (n � 3) or advanced doctoral students (n �8), supervised by the study authors, saw roughly equal numbers ofclients in each condition with an average of 3.64 (SD � 3.79,range � 1–11) ABBT clients and 3.73 (SD � 3.23, range � 1–11)AR clients. The initial therapists and the supervisors were trainedby Tom Borkovec in applied relaxation and by Zindel Segal inmindfulness therapies. Subsequent cohorts were trained by thesupervisors.

Adherence and Competency

A total of 198 (ABBT � 96; AR � 102) sessions were rated foradherence to the respective protocols by doctoral students inclinical psychology. For each client, one session was randomlychosen from Sessions 1–5, one from Sessions 6–11, and one fromSessions 12–16. For ABBT, an adherence checklist listed nineallowed and seven forbidden strategies (e.g., emphasizing theimportance of changing cognitions, explicit statements about thegoal being anxiety reduction). For AR, the checklist had sixallowed and 10 forbidden strategies (e.g., clarification of emo-tional experience, suggestions of acceptance of one’s internalexperiences, mentions of valued action). Each of the allowedelements were rated for the frequency/depth with which it wasaddressed in session, from 0 (not at all) to 2 (addressed in detail),and for the skill with which it was addressed, from 0 (poorly) to 2(skillfully). In the ABBT condition, the allowed components weretypically rated as being addressed in detail [means from 1.67(SD � 0.66) to 1.96 (SD � 0.20)] and executed skillfully [meansfrom 1.85 (SD � 0.36) to 1.98 (SD � 0.14)]. Only one session hada forbidden strategy (use of relaxation as a form of anxiety con-trol). Twenty-five (26.0%) of these sessions were rated by asecond rater with adequate reliability (� � .73). Similarly, in theAR condition, the allowed components were typically rated asbeing addressed in detail [means from 1.89 (SD � 0.37) to 1.96(SD � 0.20)] and executed skillfully [means from 1.91 (SD �0.29) to 1.97 (SD � 0.17)]. No AR sessions had a forbiddenstrategy. Twenty-eight (27.4%) of these sessions were rated by asecond rater with excellent reliability (� � .91).

Additionally, 35 AR sessions were rated by Tom Borkovec fortherapist competency with AR strategies. For each session, skillswithin the protocol for that session were rated on a 4-point Likert

scale from 0 (poor) to 3 (excellent). The average score across skillswas 2.38 (SD � 0.69), with 168 of the 187 ratings (89.8%) beinggood or excellent, 17 (9.1%) being acceptable, and 2 (1.1%) beingpoor.

Statistical Analyses

Data were examined for skewness, kurtosis, and outliers.Skewed scores [BDI–II, treatment credibility, and WAI-S (client)]were corrected with a square root transformation.

The primary analyses compared treatment differences over timein the intent-to-treat sample for ABBT and AR with mixed-effectsregression models (MRM) in SPSS Version 18.0 (Hedeker &Gibbons, 2006). Separate analyses were run for each of the out-come variables across the three time points (pretreatment, post-treatment, 6-month follow-up). Models were run assuming randomintercepts and slopes. In these hierarchical linear models, Level 1models individual change over time and Level 2 models thebetween-subjects factors. Each MRM analysis examined the over-all effect of change over time (Time), the difference betweenABBT and AR (condition), and the differences in changes overtime by condition (Time � Condition). To assess maintenance ofgains, the MRM analyses were repeated with just the post-treatment and follow-up time points. Per Dunlap, Cortina, Vaslow,and Burke (1996), Cohen’s d (Cohen, 1988) was calculated basedon the between-groups t-test value: d � 2t/�(df).

Three indices of clinically significant change were examined,following the model of other RCTs for GAD (Borkovec &Costello, 1993; Newman et al., 2011): diagnostic status, responderstatus, and end state functioning. Diagnostic status was determinedby CSR rating; those with a CSR of 3 or less were considered tono longer meet criteria for GAD. Responder status (followingBorkovec & Costello, 1993, guidelines) was defined as a reductionof symptoms of at least 20%. High end-state functioning wasdefined as falling within one standard deviation of the publishednorm on the outcome measures or receiving a GAD CSR of 3 orless (Ladouceur et al., 2000). Previous studies have used a cutoffof three out of four (Roemer et al., 2008) or three out of five(Newman et al., 2011) primary outcome measures to calculateresponder status and high end-state functioning. Thus, we calcu-lated both three out of four measures (GAD CSR, SIGH-A,PSWQ, and DASS-Stress) and three out of five measures (STAIadded to the above list).

Missing Data

MRM models analyze data using maximum likelihood estima-tion to account for missing data. This assumes that data are“missing at random.” Therefore, following the recommendation ofHedeker and Gibbons (1997), the effect of the pattern of missing-ness (completers vs. noncompleters) on the rate of change bytreatment condition was examined for each of the primary outcomevariables. For each primary outcome variable, there were nonsig-nificant effects for Completer Status � Time � Treatment Group(ps from .33 to .98). These results indicate that maximum likeli-hood estimation was an appropriate method for analyzing thesedata.

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766 HAYES-SKELTON, ROEMER, AND ORSILLO

Results

Preliminary Analyses

There were no pretreatment differences on any outcome vari-ables: GAD severity, F(1, 79) � 0.37, p � .54; SIGH-A, F(1, 79) �0.69, p � .41; PSWQ, F(1, 77) � 2.86, p � .10; DASS-Stress,F(1, 77) � 0.002, p � .96; STAI, F(1, 77) � 0.10, p � .75;BDI–II, F(1, 77) � 0.31, p � .58; quality of life, F(1, 77) � 2.58,p � .11; number of additional diagnoses, F(1, 79) � 0.92, p � .34.There were also no significant differences in the number of ses-sions completed for individuals in ABBT compared to AR [ABBT ��12.80 (SD � 5.50); AR � �13.15 (SD � 5.54); F(1, 79) � 0.08,p � .78]. Over the course of therapy, two individuals began amedication for anxiety or depression (both ABBT); two began thenended a medication within 5 weeks (1 ABBT; 1 AR); three took1–2 doses of a benzodiazepine over the entire course of therapy (2ABBT, 1 AR); three decreased or went off a medication (2 ABBT;1 AR); and six (ABBT � 3; AR � 3) received additional therapy(3 couples/family therapy; 3 check-in with previous therapists; 1grief counseling).4 There were no significant patterns of differenceacross treatments for whether or not clients were on anxiety ordepression medications [posttreatment, �2(1) � 0.91, p � .34;6-month follow-up, �2(1) � 0.04, p � .85] or had receivedadditional psychotherapy since the previous assessment [posttreat-ment, �2(1) � 0.002, p � .97; 6-month follow-up, �2(1) � 1.78,p � .18].

Primary and Secondary Outcomes

The means and standard deviations of all outcome measures ateach time point are presented in Table 2, and Table 3 presents theresults of the MRM models. The MRM model for CSR showed asignificant (large) effect for time but nonsignificant, small effectsfor condition and for the Condition � Time effect. This indicatedthat clients’ clinician-rated severity of GAD diagnosis signifi-cantly decreased across treatment and follow-up and that thischange was not different across the two treatments. Similarly, forSIGH-A, there was a significant, large effect for time but nonsig-nificant, small effects for condition and for the Condition � Timeeffect. A similar pattern of results emerged on the self-reportedprimary outcome measures, indicating that clients significantlyimproved over time on self-reports of excessive worry (PSWQ),tension and GAD symptoms (DASS-Stress), and anxiety symp-toms (STAI), but there were no differences emerged in thesechanges between treatments (with small effect sizes). MRM mod-els run for the secondary outcomes yielded consistent results, withsignificant (large) effects of time for each outcome but nonsignif-icant, small effects for both condition and Condition � Time.Together these results indicate that clients’ self-reported depres-sive symptoms and clinician-rated number of additional diagnosessignificantly decreased and self-reported quality of life increasedover time. However, there were no significant differences in theserates of change across treatments.

Process Measures

As shown in Table 2, on average clients in ABBT and clients inAR rated their respective treatments as highly credible (28.92 out

of 36), and ratings of credibility did not differ across treatments,F(1, 74) � 0.06, p � .80, d � 0.06. At the end of Session 4, bothclients (71.87 out of 84) and therapists (65.27 out of 84) reportedstrong working alliances. There were no significant differencesbetween ABBT and AR in terms of client, F(1, 64) � 0.80, p �.38, d � 0.22, or therapist, F(1, 65) � 0.94, p � .34, d � 0.24,ratings of the working alliance.

At the end of treatment, clients rated both treatments to be agood match for their needs (means of 7.41 and 7.39 for ABBT andAR, respectively) on a 9-point Likert scale. There no significantdifferences between treatments, F(1, 62) � 0.003, p � .96, d �0.01.

Maintenance of Gains

To specifically examine maintenance of gains from posttreat-ment to 6-month follow-up, we repeated the above MRM modelswith only these two time points in the models. As shown in Table4, there were no significant time, condition, or Time � Conditioneffects. All effect sizes were small, indicating comparable main-tenance of gains across follow-up.

Clinical Significance

Diagnostic change, responder status, and high end-state func-tioning at posttreatment and at 6-month follow-up are reported inTable 5. At posttreatment, 63.3–80.0% of clients in ABBT and60.6–78.8% of clients in AR exhibited clinically significantchange. Similar rates were found for ABBT (66.7–80.0%) and AR(60.6–78.8%) at follow-up. There were no significant differencesbetween conditions at either time point, with small effect sizes (dsfrom 0.01 to 0.28).

Discussion

Both an acceptance-based behavior therapy and applied relax-ation led to statistically and clinically significant change acrosstreatment and short-term follow-up. Overall, there were largeeffects for change over time in all of the primary outcome mea-sures for clients receiving either treatment. Although there aremany limits inherent in comparing outcomes across studies (i.e.,no randomization, different populations, research/therapy teameffects, measurement differences) and studies of therapy for GADhave traditionally calculated clinically significant change differ-ently, it appears that the percentage of clients in ABBT (and AR)who experienced clinically meaningful change was comparable tomost other reported treatment effects for clients with GAD. Forexample, the current study found that end-state functioning forABBT was similar to that in Ladouceur et al. (2000) and was morethan 5 percentage points higher than any condition in Newman etal. (2011) and Borkovec, Newman, Pincus, and Lytle (2002) atposttreatment and 6-month follow-up. ABBT’s rate of diagnosticchange at posttreatment was equal to or greater than remissionrates reported in Dugas et al. (2010), Wells et al. (2010), and Arch

4 Therapy check-ins and unrelated therapy were allowed by protocol;starting and stopping medication and 1–2 uses of benzodiazepines areunlikely to affect outcomes, and reducing or ceasing medication is likely tounderestimate effects of treatments.

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767ACCEPTANCE-BASED BEHAVIOR THERAPY VS. APPLIED RELAXATION

et al. (2012). Of note, the recovery rate in Wells et al. is based onlyon the PSWQ, and Arch et al is based on a small sample. However,Dugas et al. reported a slightly higher rate of responders at6-month follow-up (76% vs. 72%). Although it is difficult to makecomparisons across measures, statistical analyses, and samples thatmay differ in pretreatment characteristics, compared to those inother GAD RCTs, our pre to post treatment Cohen’s d effect sizesof 1.27 to 1.61 are slightly smaller than the Cohen’s d of 1.86 fora symptom severity composite variable (Newman et al., 2011) andare in between the effect sizes for metacognitive therapy (PSWQd � 3.41) and applied relaxation (PSWQ d � 0.95; Wells et al.,

2010).5 However, future studies should more directly comparethese treatments.

To specifically examine maintenance of gains over a 6-monthfollow-up period, we examined change from post to follow-up, aswell as the percentage of individuals meeting criteria for clinicallysignificant change. As some clients were lost to follow-up, weexamined the percentage of individuals making clinically signifi-cant changes for only the clients who completed the follow-up

5 Dugas et al. (2010) did not report Cohen’s d effect sizes.

Table 2Means and Standard Deviations (Untransformed) of Outcome Measures at Each Time Point

Measure

PretreatmentM (SD)

PosttreatmentM (SD)

6-month follow-upM (SD)

(N � 81) (N � 63) (N � 55)

Primary outcomeGAD CSR

ABBT 5.53 (0.55) 3.03 (1.38) 2.88 (1.59)AR 5.44 (0.71) 2.70 (1.57) 2.77 (1.59)

SIGH-AABBT 19.31 (6.55) 10.98 (7.06) 9.54 (7.53)AR 20.54 (6.79) 11.48 (6.20) 10.75 (6.93)

PSWQABBT 67.67 (8.10) 51.03 (8.46) 50.93 (10.72)AR 70.41 (6.22) 52.28 (10.69) 53.16 (9.93)

DASS-StressABBT 24.49 (8.73) 13.37 (6.44) 12.84 (7.68)AR 24.58 (7.64) 12.00 (8.43) 11.53 (7.75)

STAIABBT 53.94 (9.81) 43.46 (10.39) 42.88 (10.94)AR 53.30 (7.87) 43.48 (12.07) 40.72 (10.44)

Secondary outcomeBDI–II

ABBT 19.33 (11.10) 9.54 (10.76) 8.93 (11.91)AR 17.92 (10.60) 7.85 (8.51) 7.47 (8.73)

QOLIABBT 0.24 (2.14) 1.56 (1.78) 1.41 (1.80)AR 0.86 (1.18) 1.87 (1.60) 1.92 (1.41)

No. additional diagnosesABBT 0.95 (0.98) 0.55 (0.92) 0.48 (0.92)AR 1.15 (0.85) 0.52 (0.71) 0.37 (0.56)

Process measuresTreatment credibility

ABBT 29.00 (5.12) — —AR 28.84 (4.89) — —

WAI–clientABBT 70.52 (10.44) — —AR 73.15 (7.41) — —

WAI–therapistABBT 64.31 (8.13) — —AR 66.14 (7.36) — —

To what extent do you feel that this treatmentwas a good match for you?

ABBT — 7.39 (1.41) —AR — 7.41 (1.66) —

Note. Dashes indicate time points when measures were not given. GAD � generalized anxiety disorder;CSR � clinician severity rating; ABBT � acceptance-based behavior therapy; AR � applied relaxation;SIGH-A � Structured Interview Guide for the Hamilton Anxiety Rating Scale; PSWQ � Penn State WorryQuestionnaire; DASS � Depression Anxiety Stress Scale; STAI � State–Trait Anxiety Inventory; BDI–II �Beck Depression Inventory—II; QOLI � Quality of Life Inventory; WAI � Working Alliance Inventory.T

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768 HAYES-SKELTON, ROEMER, AND ORSILLO

assessment as well as while carrying forward posttreatment scores.Overall, clients in ABBT and AR maintained gains across alloutcome measures.

Clients reported comparable (high) levels of treatment credibil-ity at the beginning of treatment, as well as comparable (high)levels of match in treatments at the end of treatment. Clients andtherapists in both conditions also reported comparably strongworking alliances. These findings indicate acceptability of bothtreatments for clients with GAD.

Although our hypothesis that ABBT would outperform ouractive competitor, AR, was not supported, this is likely partiallydue to the particularly strong efficacy of AR in the current study.AR has long been considered one of the leading treatments ofGAD, and we designed our AR protocol to achieve maximalpotency. We combined all elements from Öst (2007) and Bernsteinet al. (2000); whereas some trials have used only the relaxationcomponents of AR, we dedicated significant in- and out-of-sessiontime to noticing early cues of anxiety and applying an alternateresponse. We also extended the typical length of AR from 12 to 16sessions, and our therapists were rated as highly competent by oneof the developers of AR (T. D. Borkovec). As a result, our AR

outcomes were notably stronger than those found in previous trials.For instance, Borkovec and Costello (1993) found 44% of indi-viduals receiving AR met criteria for high end-state functioning atposttreatment, but Wells et al. (2010) reported only 20% recoveredand 10% improved at posttreatment. Further research should ex-amine the optimal number of sessions for each of these treatments.

Although adherence ratings indicate that elements of ABBT(i.e., mindfulness, acceptance, and valued action) were not explic-itly introduced in AR, the use of the same therapists across bothconditions may have inadvertently introduced some nonspecificacceptance-based effects into the AR condition. It is also quitepossible that AR and ABBT have common mechanisms of change.For example, AR may promote mindfulness, acceptance, and de-centering, all theorized to be key components underlying ABBT(Hayes-Skelton, Usmani, Lee, Roemer, & Orsillo, 2012), andincreases in self-reported decentering appear to lead to symptomchange in both ABBT and AR (Hayes-Skelton, Roemer, & Orsillo,2011). More research is needed to examine the similar and diver-gent mechanisms of change underlying both of these treatments.

Contrary to hypotheses, ABBT did not lead to significantlygreater decreases in depression and comorbid conditions and in-

Table 3Results of the Mixed-Effects Regression Models Examining Change Across Treatment and Follow-Up

Effect Estimate SE t df p 95% CI d

Primary outcomeGAD CSR

Time �1.41 0.18 �7.92 116.14 �.001 [�1.76, �1.05] 1.47Condition 0.17 0.24 0.73 139.80 .47 [�0.30, 0.64] 0.12Condition � Time �0.01 0.26 0.01 115.23 .99 [�0.51, 0.52] 0.002

SIGH-ATime �5.03 0.70 �7.14 83.00 �.001 [�6.44, �3.63] 1.57Condition �0.92 1.41 �0.65 110.66 .52 [�3.71, 1.88] 0.12Condition � Time 0.03 1.03 0.03 83.25 .97 [�2.02, 2.09] 0.006

PSWQTime �8.94 1.25 �7.15 126.82 �.001 [�11.41, �6.46] 1.27Condition �2.09 1.79 �1.17 137.48 .24 [�5.62, 1.45] 0.20Condition � Time �0.15 1.82 �0.08 125.17 .94 [�3.76, 3.46] 0.01

DASS-StressTime �6.84 0.92 �7.46 85.94 �.001 [�8.67, �5.02] 1.61Condition 0.26 1.70 0.15 111.32 .88 [�3.12, 3.64] 0.03Condition � Time 0.82 1.34 0.61 86.23 .54 [�1.85, 3.48] 0.13

STAITime �5.87 0.91 �6.45 67.71 �.001 [�7.68, �4.05] 1.57Condition 0.42 2.14 0.20 92.54 .84 [�3.82, 4.67] 0.04Condition � Time 0.10 1.34 0.07 69.13 .94 [�2.57, 2.77] 0.02

Secondary outcomeBDI–II

Time �0.87 0.15 �5.64 66.92 �.001 [�1.18, �0.56] 1.38Condition 0.22 0.32 0.68 92.27 .50 [�0.41, 0.84] 0.14Condition � Time �0.01 0.23 0.02 67.76 .99 [�0.45, 0.46] 0.004

QOLITime 0.50 0.12 4.07 120.24 �.001 [0.26, 0.75] 0.74Condition �0.59 0.37 �1.57 103.24 .12 [�1.33, 0.16] 0.31Condition � Time 0.11 0.18 0.59 122.50 .55 [�0.26, 0.47] 0.11

No. additional diagnosesTime �0.38 0.07 �5.16 130.85 �.001 [�0.52, �0.23] 0.90Condition �0.19 0.18 �1.03 127.26 .30 [�0.54, 0.17] 0.18Condition � Time 0.15 0.11 1.38 132.63 .17 [�0.06, 0.36] 0.24

Note. SE � standard error; df � degrees of freedom; CI � confidence interval; GAD � generalized anxiety disorder; CSR � clinician severity rating;SIGH-A � Structured Interview Guide for the Hamilton Anxiety Rating Scale; PSWQ � Penn State Worry Questionnaire; DASS � Depression AnxietyStress Scale; STAI � State–Trait Anxiety Inventory; BDI–II � Beck Depression Inventory—II; QOLI � Quality of Life Inventory.

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769ACCEPTANCE-BASED BEHAVIOR THERAPY VS. APPLIED RELAXATION

creases in quality of life than did AR. We predicted these differ-ences because ABBT explicitly targets mechanisms thought tounderlie a range of disorders (Hayes et al., 1996). As expected,ABBT did have a significant impact on these outcomes, with largeeffect sizes. Unexpectedly, AR demonstrated a comparable impact.Extensive focus on reducing habits of anxious responding may inturn help clients naturally engage more in their lives, even withoutan explicit focus on behavioral action. More research is needed toexplore the mechanisms that underlie these effects within AR.

As with all studies, this study had a number of limitations. Tocontrol for therapist effects, all therapists administered both treat-ments. This raises the possibility of treatment diffusion or differ-ences in therapist’s allegiance. However, a large proportion ofclients were seen by therapists with a stronger background intraditional CBT, and adherence ratings showed that therapists wereadherent to their respective treatment conditions. Further, althoughthe investigators were developers of ABBT, AR competence wasrated very highly by one of the developers of AR. An additionallimitation is that all of our therapists were relatively inexperienced(graduate students and postdoctoral fellows), which may havereduced the efficacy of interventions. Further, as with most RCTs,

this study favored internal over external validity. For example,there was a fixed treatment length, and treatment followed aprotocol that did not allow for the possibility of adapting thetherapy with treatment elements from other approaches. Becauseof these limitations, it is unclear how ABBT would perform inroutine clinical practice. Similarly, this sample was predominantlyWhite, limiting the conclusions that can be made about the efficacyof ABBT with more diverse populations. On the basis of qualita-tive interviews of ABBT clients who ascribed to a nondominantidentity (race, ethnicity, sexual orientation, religion, or socioeco-nomic status), clients found ABBT fit well culturally and partic-ularly appreciated the emphasis on valued living and the flexibilityof the therapy and the therapists (Fuchs et al., 2012). However,more research is needed to systematically assess the portability ofthis therapy to other settings and populations. Similarly, the cur-rent study did not address the question of differential dissemina-tion. For example, AR is simple, which makes it seem like a goodcandidate for dissemination. However, it is more inflexible anddemanding in terms of client time required and so may not be aseffective with clients who are not receiving free treatment; incontrast, this ABBT is flexible and adapts to client’s circum-

Table 4Results of the Mixed-Effects Regression Models Examining Maintenance of Gains From Posttreatment to 6-Month Follow-Up

Effect Estimate SE t df p 95% CI d

Primary outcomeGAD CSR

Time 0.13 0.26 0.47 55.78 .64 [�0.40, 0.66] 0.12Condition 0.50 0.64 0.79 60.73 .43 [�0.77, 1.77] 0.16Condition � Time �0.17 0.39 �0.43 56.41 .67 [�0.95, 0.62] 0.11

SIGH-ATime �0.30 0.99 �0.30 56.18 .76 [�2.29, 1.69] 0.08Condition 0.38 2.51 0.15 63.02 .88 [�4.65, 5.40] 0.04Condition � Time �0.88 1.47 �0.60 56.52 .55 [�3.82, 2.06] 0.16

PSWQTime 1.97 1.37 1.44 54.39 .16 [�0.78, 4.72] 0.39Condition 0.91 3.57 0.25 59.21 .80 [�6.24, 8.06] 0.06Condition � Time �2.02 2.05 �0.99 55.26 .33 [�6.12, 2.08] 0.27

DASS-StressTime �0.21 1.17 �0.18 56.79 .86 [�2.56, 2.14] 0.05Condition 1.19 3.01 0.40 62.82 .69 [�4.82, 7.21] 0.10Condition � Time 0.17 1.73 0.10 57.35 .92 [�3.30, 3.64] 0.03

STAITime �1.61 1.35 �1.20 54.00 .24 [�4.32, 1.08] 0.33Condition �1.89 3.88 �0.49 114.48 .63 [�9.57, 5.78] 0.09Condition � Time 1.87 2.01 0.93 54.88 .36 [�2.17, 5.90] 0.25

Secondary outcomeBDI–II

Time 0.07 0.24 0.29 53.43 .77 [�0.42, 0.56] 0.08Condition 0.42 0.63 0.67 57.99 .50 [�0.84, 1.68] 0.18Condition � Time �0.08 0.36 �0.23 54.06 .82 [�0.81, 0.64] 0.06

QOLITime 0.03 0.23 0.14 53.84 .89 [�0.42, 0.48] 0.04Condition �0.16 0.62 �0.25 105.38 .80 [�1.39, 1.08] 0.05Condition � Time �0.15 0.34 �0.44 54.80 .66 [�0.84, 0.54] 0.12

No. additional diagnosesTime �0.12 0.13 �0.94 53.17 .35 [�0.37, 0.13] 0.26Condition �0.08 0.32 �0.26 97.45 .80 [�0.72, 0.56] 0.05Condition � Time 0.12 0.19 0.63 54.25 .53 [�0.26, 0.49] 0.17

Note. SE � standard error; df � degrees of freedom; CI � confidence interval; GAD � generalized anxiety disorder; CSR � clinician severity rating;SIGH-A � Structured Interview Guide for the Hamilton Anxiety Rating Scale; PSWQ � Penn State Worry Questionnaire; DASS � Depression AnxietyStress Scale; STAI � State–Trait Anxiety Inventory; BDI–II � Beck Depression Inventory—II; QOLI � Quality of Life Inventory.

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770 HAYES-SKELTON, ROEMER, AND ORSILLO

stances, which was mentioned as a strength of ABBT by ourclients (Fuchs et al., 2012). Additionally, at this point, there is littleinformation regarding moderators and predictors of outcome ineither ABBT or AR. More evidence of moderators and differentialpredictors would help address these questions of differential dis-semination.

To address these limitations and further understand the dissem-ination and usefulness of ABBT across contexts, future studiesshould explore adaptations that will make ABBT more efficient forother settings—for example, as a workshop intervention (e.g.,Blevins, Roca, & Spencer, 2011) or in primary care settings—aswell as responsive to contextual and cultural factors (Fuchs, Lee,Roemer, & Orsillo, 2013; Rucker Sobczak & West, 2013). Inaddition to studying the application of ABBT to naturalistic set-tings, researchers should examine the portability and disseminationof this treatment to clinical practice. These dissemination effortswill be aided by a better understanding of common and uniquemechanisms of change across these two treatments, as well differ-ential predictors of treatment outcome.

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Table 5Percentage of Treatment Completers (n � 63) Meeting Criteriafor Diagnostic Change, Responder Status, and High End-StateFunctioning at Posttreatment and 6-Month Follow-Up

Assessment

Diagnostic change

�2 p dABBT AR

Post 80.0% (24/30) 69.7% (23/33) 0.88 .35 0.246-month 72.0% (18/25) 70.0% (21/30) 0.03 .87 0.05

66.7% (20/30) 73.3% (22/33) 0.00 .99 0.01Responder status

(3 of 4)Post 70.0% (21/30) 78.8% (26/33) 0.64 .42 0.206-month 76.0% (19/25) 71.4% (20/28) 0.14 .71 0.10

70.0% (21/30) 72.7% (24/33) 0.06 .81 0.06Responder status

(3 of 5)Post 73.3% (22/30) 78.8% (26/33) 0.26 .61 0.136-month 76.0% (19/25) 78.6% (22/28) 0.05 .82 0.06

73.3% (22/30) 78.8% (26/33) 0.26 .61 0.13High end-state

(3 of 4)Post 63.3% (19/30) 60.6% (20/33) 0.05 .82 0.066-month 80.0% (20/25) 67.8% (19/28) 1.00 .32 0.28

73.3% (22/30) 60.6% (20/33) 1.14 .28 0.27High end-state

(3 of 5)Post 73.3% (22/30) 72.7% (24/33) 0.00 .96 0.016-month 80.0% (20/25) 75.0% (21/28) 0.19 .66 0.12

76.7% (23/30) 66.7% (22/33) 0.77 .38 0.22

Note. Treatment completers are those who completed at least 13 of the 16sessions. Italic type indicates the last available values carried forward forthe calculations for participants who were designated treatment completersbut who did not attend the 6-month follow-up assessment. Responder statusand end-state functioning were calculated two ways, following Roemer etal. (2008; responses on 3 of 4 measures, CSR, SIGH-A, PSWQ, andDASS-Stress) and Newman et al. (2011; responses on 3 of 5 measures,CSR, SIGH-A, PSWQ, DASS-Stress, and STAI). ABBT � acceptance-based behavior therapy; AR � applied relaxation; post � posttreatmentassessment; 6-month � 6-month posttreatment follow-up assessment;CSR � clinician severity rating; SIGH-A � Structured Interview Guide forthe Hamilton Anxiety Rating Scale; PSWQ � Penn State Worry Ques-tionnaire; DASS � Depression Anxiety Stress Scale; STAI � State–TraitAnxiety Inventory.

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Received August 15, 2012Revision received January 22, 2013

Accepted March 15, 2013 �

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773ACCEPTANCE-BASED BEHAVIOR THERAPY VS. APPLIED RELAXATION