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Burlingame, G.M., Seebeck, J.D., Janis, R.A., Whitcomb, K.E., Barkowski, S., Rosendahl, J., & Strauss, B. (2016). Outcome differences between individual and group formats when identical and nonidentical treatments, patients, and doses are compared: A 25-year meta-analytic perspective. Psychotherapy, 53, 446-461.

With increasing service demands being put on mental health systems, clinicians and administrators are looking to more efficient ways of providing care to more patients. One option is group therapy in which more patients can be treated with fewer resources. However, are groups as effective as individual therapy for mental disorders? This meta-analysis by Burlingame and colleagues addresses this question by examining 67 studies in which group and individual therapy were directly compared within the same study. The majority of studies included adults with anxiety, mood, or substance use disorders, with some studies focusing on medical conditions, eating or personality disorders. Two-thirds of studies were of cognitive-behavioral therapy, but other treatment types like interpersonal, psychodynamic, and supportive therapy were also tested. Groups were defined as having at least 3 patients per group. The average number of sessions for group and individual therapy were equivalent (group M = 14.67, SD = 8.75; individual 15.94, SD = 14.37)), and as expected group therapy sessions were longer in minutes (M = 100.39, SD = 30.87) than individual therapy sessions (M = 56.55, SD = 14.37) given the multi-person demands of groups. Groups were primarily closed to new members after starting, they tended to have homogenous membership based on diagnosis, and groups tended to be co-led by 2 therapists. Individual and group therapy were not significantly different for all disorders and outcomes at post-treatment (g = -0.03; 95%CI = -0.10, 0.04), short-term follow-up (g = 0.01; 95% CI = -0.13, 0.11), and long-term follow-up (g = 0.00; 95% CI= -0.12, 0.13). Drop out rates for group therapy (17.28%) and individual therapy (14.96%) were not significantly different (OR = 1.10; 95% CI = 0.90, 1.33), and patients were likely to accept group therapy (88.76%) as often as they accepted individual therapy (84.83%) when one or the other was offered. Pre- to post-treatment effect sizes were moderately large for both interventions (group: g = 0.60, 95% CI = 0.48, 0.72; individual: g = 0.53, 95% CI = 0.42, 0.65). Patients presenting with depression, substance us, anxiety, or eating disorders had the highest level of improvement.

Practice Implications

When identical treatments, patients, and doses are compared, individual and group therapy resulted in equivalent outcomes across of a variety of disorders. This is good news for clinicians and agencies looking to maximize resources to treat more patients. However, running a group is more complex than providing individual therapy. Finding a sufficient number of patients to start a group, assessing and preparing each patient prior to starting a group, writing a note per patient per session, and managing attrition is logistically more challenging. Further, most therapists are not formally trained to provide group interventions and so they may find the task of managing a substantially larger amount of within-session group process information to be complex. Finally, as Burlingame and colleagues indicate, there are institutional considerations so that group programs require a milieu that supports group referrals and flexibility in scheduling. Nevertheless the findings of this meta analysis indicate the potential for group therapy to provide efficacious treatments for mental disorders.

Munder, T., Brütsch, O., Leonhart, R., Gerger, H., & Barth, J. (2013). Researcher allegiance in psychotherapy outcome research: An overview of reviews. Clinical Psychology Review, 33, 501-511.

Although evidence for the efficacy of psychotherapy is largely uncontested, there remains debate about whether one type of treatment is more effective than another. This debate continues despite a recent American Psychological Association (APA) resolution on the equivalent efficacy of most systematic psychotherapy approaches. There are many aspects to this debate (e.g., some treatments are more researched than others and so appear to be better; symptom focused measurements are more sensitive to change and so may favour one treatment over another; some treatments are more amenable to manualization and short term application; etc.). One element of the debate that has received a lot of attention is researcher allegiance. Researcher allegiance refers to researchers preferring one treatment approach over another, and this preference may bias comparative outcome trials in favour of the preferred therapy. Researcher allegiance is measured by assessing primary researchers’ publication history or by their self-declared preference for a particular therapy approach. There exist 30 meta analyses that assessed researcher allegiance since the 1980s. These meta analyses focused on different therapy types, client populations (adults, children), and research designs (randomized trials, naturalistic effectiveness studies). However, some meta analyses have reported contradictory results for the researcher allegiance effect. This could be due to the different foci of the meta analyses (i.e., different treatment approaches, patient populations, age groups, etc.), and also possibly due the allegiance of those conducting the meta analyses. Munder and colleagues (2013) conducted a mega analysis of these meta analyses. As the name implies, a mega analysis aggregates the findings of available meta analyses. Munder and colleagues found a significant moderate effect of researcher allegiance. Researcher allegiance was consistent across patient populations, age groups, outcome measures, type of study design, and year of publication.

Practice Implications

As the APA resolution indicates, psychotherapy is the informed and intentional application of clinical methods and interpersonal stances derived from established psychological principles. Evidence-based practice in psychotherapy is "the integration of the best available research with clinical expertise in the context of patient characteristics, culture and preferences". The results of this mega analysis undermine the claim of some comparative outcome studies that suggest that one evidence-based psychotherapy is more effective than another.

Author email: tmunder@uni-kassel.de