Simon, W. (2009). International Journal of Psychiatry in Clinical Practice, 13(2), 153-165.
Assessing the number of patients who maintain their gains after the completion of therapy has been of interest to psychotherapy outcome researchers. The current study examines evidence related to the maintenance of treatment gains in individuals diagnosed with Cluster C personality disorders. Fifteen studies, published between 1982 and 2006, met the criteria for inclusion. The effect size standardized mean difference statistic was applied. In the majority of cases, most of the improvement occurred between pretreatment and posttreatment. However, social skills training often produced effect sizes that were larger for posttreatment follow-up. The study indicates that therapy gains are usually maintained at follow-up for Cluster C clients treated with cognitive-behavioral and psychodynamic approaches as well as social skills training. Uncertainty remains whether DPD, AVPD or OCPD patients benefited most from therapy
Payne, K. T. & Marcus, D. K. (2008). Group Dynamics: Theory, Research, and Practice, 12(4), 268-278.
This review examined the effectiveness of group psychotherapy for older (55+) adults. Results from 44 studies with pre-post designs and 27 controlled studies indicated that group psychotherapy benefits older adults, with average rs of .42 and .24 for pre-post and controlled designs, respectively. The type of therapy provided and the age of the clients were associated with pretreatment to posttreatment improvement. Clients in cognitive-behavioral group therapy improved more than those receiving reminiscence therapy. The older the average age of the group members, the less they benefited from therapy. Number of sessions attended, length of therapy sessions, the percentage of women in the group, and client living situation were not significant moderators of outcome. Overall, group interventions for older adults appear to be effective and the average effect size for pre-post studies was quite similar to those yielded by meta-analyses of group therapy with younger adults and adolescents. However, the average effect size for controlled studies of group therapy with older adults appears to be somewhat smaller than the values reported in meta-analyses with younger clients.
Grissom, R. J. (1996). Journal of Consulting and Clinical Psychology, 64(5), 973-982.
The "probability of superiority estimate" (PS) estimates the probability that a randomly sampled client from a population given a treatment will have an outcome that is superior to that of a randomly sampled client from a population given another treatment. The meta-analytic clinical outcome literature was examined to calculate mean PS (PS) for comparisons involving therapy versus control, the raw versus placebo, therapy versus therapy, and placebo versus control. The range of PS was found to be approximately .7 ± .2, with median PS greatest when therapy and control are compared ( Mdn PS[sub]TC[/sub] = .70, where T = therapy and C = control)