The efficacy of recommended treatments for veterans with PTSD: A metaregression analysis
Introduction
Deployed soldiers and veterans have risked exposure to life-threatening stressors, such as combat, injury, and witnessing suffering and death. Whilst most veterans were healthy, resilient individuals able to cope with such stressors, between 3 and 17% developed posttraumatic stress disorder (PTSD) in the first years after deployment (Engelhard et al., 2007, Richardson et al., 2010). PTSD is a mental disorder that evokes severe distress, chronic suffering and impairment. Its core symptoms comprise re-experiencing traumatic content, persistent avoidance of traumatic content, negative alterations in cognitions, and arousal and reactivity (American Psychiatric Association, 1994, American Psychiatric Association, 2013). More than half a million American veterans sought PTSD care at a cost of three billion dollars (Institute of Medicine [IOM], 2014).
Clinical-practice guidelines recommend psychological treatment interventions to target PTSD (Australian Centre for Posttraumatic Mental Health (ACPMH), 2007; Institute of Medicine (IOM), 2008, International Society for Traumatic Stress Studies (ISTSS), 2009; National Institute for Clinical Excellence (NICE), 2005; The management of post-traumatic stress Working Group, 2004, The management of post-traumatic stress Working Group, 2010). The following first-choice interventions are recommended by most or all clinical practice guidelines: eye movement desensitization and reprocessing (EMDR), exposure therapy (ET), cognitive therapy (CT), cognitive restructuring therapy (CR), cognitive processing therapy (CPT), and trauma-focused cognitive behavioural therapy (TF-CBT). Stress management therapy (SMT) has also been mentioned because the VA-DoD guidelines (The management of post-traumatic stress Working Group, 2010) recommend stress inoculation therapy (SIT), which is a SMT intervention. Recent empirical evidence confirmed that veterans respond reasonably well to these recommended interventions (Kitchiner, Roberts, Wilcox, & Bisson, 2012). However, veterans benefitted less from psychotherapy than non-military PTSD populations (Watts et al., 2013) and meta-analyses reported smaller treatment effect sizes for traumatised veterans (d = .68–.81) versus non-veterans (d = 1.04–1.83) (Bradley et al., 2005, Goodson et al., 2011). The majority of veterans with PTSD (78%) still receive PTSD treatment after four years of treatment (Congress of the United States (CBO), 2012). Psychotherapies apparently deliver only limited PTSD symptom-reduction in the veteran population. Psychotherapy studies face further critique that their findings are mostly based on the average responses of large treatment groups that ignore within-person variability (i.e., individual factors that influence outcome). As a response, researchers have begun to emphasize the importance of individual treatment responses and mechanisms of therapeutic change as ‘the surest way to enhance efficacy’ (Barlow, Bullis, Comer, & Ametaj, 2013).
There are various explanations why veterans benefit less from treatment than other PTSD populations. Several authors highlighted the intensive, repetitive and interpersonal nature of combat-related traumatic events as a complicating factor (Pietrzak, Whealin, Stotzer, Goldstein, & Southwick, 2011). Traumatic combat experiences are often less straightforward than single traumatic events (e.g., a car accident) and are known to decrease PTSD treatment effectiveness (Price, Gros, Strachan, Ruggiero, & Acierno, 2013). On a patient level, treatment complications are reported among more symptomatic veterans. These veterans experienced more severe symptoms and more comorbid disorders, and include severe PTSD levels (Belsher et al., 2012, Boden et al., 2012a, Boden et al., 2012b, Johnson and Lubin, 1997, Owens et al., 2008), severe anger issues (Forbes et al., 2003, Forbes et al., 2008, Lloyd et al., 2014, Owens et al., 2008), comorbid alcohol abuse (Forbes et al., 2003, Forbes et al., 2008), and comorbid depression (Forbes et al., 2003). The results however are not unequivocal, a minority of studies reported no negative and even positive treatment effects for more symptomatic veterans (Fontana et al., 2012, Forbes et al., 2002, Richardson et al., 2014, Steindl et al., 2003). From a developmental perspective, veterans diagnosed with a borderline personality disorder (Forbes et al., 2002), a ‘disorders of extreme stress not otherwise specified’ (DESNOS) diagnosis (Ford & Kidd, 1998), and dysfunctional attachment style (Forbes, Parslow, Fletcher, McHugh, & Creamer, 2010), fared worse in treatment. The results are again not unequivocal, Walter, Kiefer, and Chard (2012) did not find any effects for personality disorders on PTSD treatment, and early childhood experiences did not predict treatment outcome (Johnson & Lubin, 1997). From a social perspective, veterans performed worse in treatment if they were socially isolated (Forbes et al., 2002), had poor functioning families, and experienced marital distress (Evans et al., 2010, Evans et al., 2009). Last, organisational and treatment factors also influence outcome. For example, PTSD treatment success was predicted by positive treatment expectations and longer treatment duration (Belsher et al., 2012), as well as a willingness for patients to therapeutically change (Rooney et al., 2007).
The evidence for treatment predictors may seem abundant from these articles, but is in reality scant. Most of these factors were studied only once or twice which does not offer a firm base for predictive statements. The vast majority of studies examined univariate relationships between a single predictor and treatment outcome, thus not taking the interrelatedness between predictor variables into account. Only a few studies investigated the effects of multiple predictors simultaneously (e.g., Forbes et al., 2008). Many questions related to mechanisms of change also remain unanswered. It is unclear whether important veteran patient characteristics such as age and gender, should be treated in the same manner as civilians (IOM, 2008). There is also debate about the most optimal content and format for delivering treatment; is group-therapy formats are as effective as individual-therapy formats (The management of post-traumatic stress Working Group, 2010), and is a trauma-focus is imperative for PTSD treatment (Benish et al., 2008, Ehlers et al., 2010, Wampold et al., 2010). Consequently, there is a need to assess the influence of veteran patient and treatment characteristics on treatment outcome. Using meta-analysis, the information from numerous studies can be combined to strengthen predictive evidence, test treatment guideline recommendations and help resolve conflicting predictor study outcomes. Up till now, meta-analyses about predictive factors are however lacking.
Prognostic research offers novel opportunities to assess the impact of specific factors on treatment outcome. The term prognosis refers to the probability of an individual developing a particular state of health (e.g., treatment outcome) over a specific time, based on his or her clinical and non-clinical profile (Moons, Royston, Vergouwe, Grobbee, & Altman, 2009). Prognostic research thus allows us to make inferences or predictions about expected treatment outcomes for individual patients. It advances understanding of therapeutic change mechanisms, enables psychotherapy improvements, and the creation of clinical decision making tools (Altman, 2001, Moons et al., 2009a). Such tools enable clinicians to select suitable interventions tailored to the specific needs of each individual. The present prognostic study aims to identify PTSD psychotherapy treatment efficacy predictors for traumatised veterans. It is the first meta-analysis to use data from guideline recommended PTSD psychotherapy intervention studies in search of predictors.
Section snippets
Search strategy
We undertook a systematic literature search to retrieve all first-choice psychotherapy studies that target PTSD among veterans and active military personnel. The search was performed in the following databases and their accompanied search registries: PubMed (NCBI), Pilots (ProQuest), PsycINFO (Ovid), Embase (Elsevier), Medline (OvidSP), CINAHL (Ebsco Host), and Web of Science (ISI Web of Knowledge). The search domains and their respective synonyms were combined into search syntaxes using
Results
Fig. 1 shows an overview of the study search and selection process. Forest plots for random-effects meta-analysis are presented in Fig. 2. The search was performed in June 2014 and yielded 2149 unique articles from five databases. The majority of articles (n = 2092) were excluded after screening. Major reasons for exclusion were: absence of PTSD diagnosis in study sample (n = 374), no veteran or active soldier sample (n = 511), not a psychotherapy study, or psychotherapy did not target PTSD, or PTSD
Discussion
The present meta-analysis investigated PTSD psychotherapy outcome predictors for veterans and soldiers. An individual or combination (group and individual) therapy format, (prolonged) ET and CPT interventions as well as the number of trauma-focused therapy sessions predicted increased treatment effectiveness. In contrast, group-only therapy, EMDR and SMT interventions, negatively impacted treatment effectiveness. EMDR was however no longer associated with decreased treatment effectiveness after
Role of funding sources
No funding has been provided by a commercial company, grant, charity or government department.
Contributors
Each author contributed to the article in the following manner: Study concept and design: J.F.G. Haagen, G.E. Smid, J.W. Knipscheer and R.J. Kleber. Study protocol and literature searches: J.F.G. Haagen and G.E. Smid. Statistical analysis: J.F.G. Haagen and G.E. Smid. First draft: J.F.G. Haagen. Study supervision: J.W. Knipscheer and R.J. Kleber. All authors contributed to and have approved the final manuscript.
Conflict of interest
All authors declare that they have no conflicts of interest.
Acknowledgements
We would like to thank Professor Dr. Joop Hox for his meta-analytical advice and Gerko Vink (MSc) for his valuable instructions concerning the application of missing imputation techniques in meta-analytic studies.
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