The expanding evidence for the efficacy of ACT:

results from a meta analysis on clinical applications

Earlier meta analysis

• Hayes et al 2006• Ost, 2008• Powers et al, 2009• Veehof at al, 2011• Ruiz, 2012

• For Cohen's d an effect size of 0.2 to 0.3 might be a "small" effect,

• around 0.5 a "medium" effect • and 0.8 to infinity, a "large" effect

Hayes et al 2006

• Until spring 2005• the meta-analysis examines the average

relationship between the AAQ or its specific variants and measures of psychopathology and quality of life.

• And, a simple version of outcome analysis• 17 studies, N=704

Criteria for inclusion

• RCT• articles and any other available data set

(dissertation, paper)• Levitt, 2004 is not a treatment study• Acceptance based

Results

• weighting average effect sizes by the number of cases that produced the effect

• ACT compared to general control conditions (9 studies): post: d =.66 (N=704) FU: d =.66 (N=519)

• Comparisons between ACT and structured interventions (12 studies): post: d =.48 (N=456) FU: d =.63 (N=404)

• comparisons between ACT and C(B)T (4 studies): d =.73 at post and d = .83 at FU

Overlap with other MA

• 12 studies included in Ost• 12 studies included in Powers• 1 study included in Veehof• 5 studies included in Ruiz • 8 studies included in A-Tjak

Öst, 2008

• from 1985 to mid 2007• ACT and other third wave therapies• Complicated system of matching studies of

ACT to studies of CBT• Rating methodological quality of studies:• CBT studies M = 27.8 (SD = 4.2) • ACT studies M = 18.1-18.32 (SD = 5.0).

Criteria for inclusion

• RCT (13 studies, N = 677)• published or in press• Published in English• Acceptance based

Results

• an overall mean ES of 0.68 for ACT (13 studies; N = 677)

• ACT compared to waitlist (2 studies) ES = 0.96• ACT compared to TAU (5 studies) ES = 0.79 • ACT compared to an active treatment (two

studies comparing ACT to (CT) and one to Systematic Desensitization) ES = 0.53

Overlap with other MA

• 12 studies included in Hayes (one dissertation now as article)

• 13 studies included in Powers• 1 study included in Veehof• 4 studies included in Ruiz• 9 studies included in A-Tjak

Powers et al, 2009

• Until March 2008• RCT• 18 studies (N = 917)• Separate analysis for depression (2 studies),

physical health (5 studies) and other mental health conditions (7 studies)

Criteria for inclusion

• RCT• Acceptance based treatments• mental and physical health disorders• Published in English

Results

• ACT versus all control conditions ES = 0.42 on primary outcome measures

• ACT versus established treatments ES = 0.18 • ACT versus waitlist condition and

psychological placebos ES = 0.68 on secondary measures

• ACT versus TAU ES = 0.42 on secondary measures

Overlap with other MA

• 12 studies included in Hayes (one dissertation now as article)

• 12 studies included in Öst• 1 study included in Veehof• 6 studies included in Ruiz• 12 studies included in A-Tjak (one study

published in 2012 FU information)

Veehof et al, 2011

• ACT and mindfulness• Rating methodological quality with an 8-point

scale, based on criteria by the Cochrane Collaboration and the validated Jadad scale

• Until Januari 2009• 22 studies, of which 9 RCT, 2 of which are

concerning ACT (also in other MA)• Chronic pain only

Ruiz, 2012

• Until the end of July 2012• 16 studies (N= 954) comparing ACT to CBT• Not all CBT recognized as such by author(s)• outcome or mediation/moderation

Criteria for inclusion

• Published and unpublished studies• outcome or mediation/moderation study • comparing full treatments of face-to-face ACT

versus traditional CBT • Published in English or Spanish

Results

• ACT better than CBT on primary outcomes (Hedges’s g= 0.40).

• Post: g+= 0.37 FU: g+= 0.42 • no statistically significant differences in

depression (g+= 0.27) and anxiety outcomes (g+= 0.14) between ACT and CBT

• supports the hypothesized mediators suggested in the ACT model

Overlap with other MA

• 5 studies included in Hayes• 4 studies included in Öst• 6 studies included in Powers• 7 studies included in A-Tjak

A-Tjak et al submitted

• Michelle Davis, Southern Methodist University• Nexh Morina, University of Amsterdam• Mark Powers, Southern Methodist University• Jasper Smits, Southern Methodist University• Paul Emmelkamp , University of Amsterdam

• Until March 2013• 39 RCT, N = 1.818 • Methodological quality measured• a mean score of 23.88 for ACT studies (SD =

4.96) on the methodology rating scale

Criteria for inclusion

• RCT, acceptance based treatments• Published or retreivable information• Only clinically relevant populations: psychiatric

or medical diagnosis or high score on relevant psychological questionnaire, treatment seeking/needing

• at least 10 participants in the active condition(s) at post treatment

Results on primary outcomes

• ACT outperformed control conditions (39 studies, N = 1.818) Hedges’s g = 0.70

• waitlist and psychological placebos (14 studies, N = 583) Hedges’s g = 0.74

• TAU (14 studies, N =509) Hedges’ g = 1.13 • established treatments (i.e., CBT, CT, or HBE)

(7 studies, N = 401) Hedges’s g = 0.07, non significant

Results on secondary outcomes

• ACT was superior to control conditions (34 studies, N = 1.556 participants) Hedges’s g = 0.44

• life satisfaction/quality measures (14 studies, N = 731) Hedges’s g = 0.60

• process measures (16 studies, N = 733) Hedges’s g = 0. 86

Results per group of conditions

• ACT was superior control conditions for anxiety/depression (8 studies, N = 378 ) Hedges’s g = 1.35

• For addiction (8 studies, N = 501) Hedges’s g = 0.35

• For somatic complaints (15 studies, N = 682) Hedges’s g = 0.62

• For other mental disorders (8 studies, N = 258) Hedges’s g = 0.86

Mean A-Tjak** Mean Ost*ACT ACT CBT DBT

1 Clarity of sample description 1,71 1,23 1,62 1,542 Severity/ chronicity of the disorder 1,41 1,31 1,73 1,543 Representative-ness of the sample 1,68 1,08 1,73 1,464 Reliability of the diagnosis 0,66 0,15 1,32 0,775 Specificity of outcome measures 1,90 1,77 2,00 1,776 Reliability and validity of outcome measures 1,90 1,54 2,00 1,237 Use of blind evaluators 0,54 0,31 0,58 0,778 Assessor training 0,39 0,31 0,77 0,699 Assignment to treatment 1,07 0,85 1,19 1,00

10 Design 0,95 1,23 1,62 1,1511 Power analysis 0,27 0,00 0,38 0,1512 Assessment points 1,07 0,92 1,27 0,77

13Manualized, replicable, specific treatment programs 1,44 1,54 1,69 1,54

14 Number of therapists 0,90 0,23 1,08 0,7715 Therapist training/ experience 1,20 0,69 1,42 0,9216 Checks for treatment adherence 0,76 0,15 0,92 0,3117 Checks for therapist competence 0,78 0,00 0,23 0,0018 Control of concomitant treatments 0,49 0,23 1,00 0,2319 Handling of attrition 1,39 0,85 1,19 0,62

20Statistical analyses and presentation of results 1,88 1,69 2,00 1,54

21 Clinical significance 0,66 0,69 1,04 0,3122 Equality of therapy hours 0,83 1,55 1,86 0,36

TOTAL 23,88 18,32 27,80 19,40* ICC for the total score .92. **ICC for the total score = .99

Methodological Rating Scale Ost (2008)

Overlap with other MA

• 8 studies included in Hayes• 8 studies included in Öst• 11 studies included in Powers • 7 studies included in Ruiz• 22 studies included in no other MA

until outcome analysis study participantsHayes et al, 2006 spring 2005 Average effect sizes 17 704Öst, 2008 mid 2007 Meta analysis 13 677Powers et al, 2009 march 2008 Meta analysis 18 917Veehof et al 2011 Januari 2009 Randomized and/or controlled 2 39Ruiz, 2012 July 2012 Meta analysis 16 954A-Tjak et al, submitted March 2013 Meta analysis 39 1818

form of information treatment populationHayes et al, 2006 (un)published acceptance bases or single intervention broad

Öst, 2008published or in press acceptance based mental health

Powers et al, 2009published or in press acceptance based mental health

Veehof et al 2011published or in press ACT chronic pain

Ruiz, 2012 (un)published ACT vs CBT broadA-Tjak et al, submitted (un)published acceptance based diagnosable mental health

Comparison of aspects of MA

all control waitlist, placebo/ TAU structured interventionsC(B)T/established treatments

Primary measures general post FU general post FU general post FU general post FUHayes et al, 2006 0.99 0.71 0.66 0.66 0.53 0.48 0.63 0.73 0.83Öst, 2008 0.68 0.96/0.79Powers et al, 2009 0.42 0.18Ruiz, 2012 0.40 0.37 0.42A-Tjak et al, submitted 0.70 0.74/1.13 0.07

Comparison on primary and process measures

all control waitlist, placebo, TAU structured interventionsC(B)T/established treatments

Process measures general post FU general post FU general post FU general post FUHayes et al, 2006Öst, 2008Powers et al, 2009Ruiz, 2012A-Tjak et al, submitted 0.86

all control waitlist, placebo, TAU structured interventionsC(B)T/established treatments

Secundary measures general post FU general post FU general post FU general post FUHayes et al, 2006Öst, 2008Powers et al, 2009 0.68/0.42Ruiz, 2012A-Tjak et al, submitted 0.44

Comparison on secundary measures and quality of life

all control waitlist, placebo, TAU structured interventions C(B)T/established treatmentsLife quality general post FU general post FU general post FU general post FUHayes et al, 2006Öst, 2008Powers et al, 2009Ruiz, 2012A-Tjak et al, submitted 0.60

anxiety/depression depression distress addiction somatic complaints other mental healthHayes et al, 2006Öst, 2008Powers et al, 2009 0.76 0.03 0.39 0.60Ruiz, 2012A-Tjak et al, submitted 1.35 0.35 0.62 0.86

Comparison per group of conditions