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.
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.