Posttraumatic stress disorder arising after road traffic collisions: patterns of response to cognitive-behavior therapy.

Road traffic collisions (RTCs) are common precipitants of posttraumatic stress disorder (PTSD). Two preliminary studies suggest that cognitive-behavior therapy (CBT) is, on average, effective in treating this disorder, although the major patterns of treatment outcome remain to be identified. Such outcomes might include treatment response, partial response, and response followed by relapse. To identify these patterns. 50 people with RTC PTSD completed a 12-week course of CBT, with outcome assessment extending to 3-month follow up. Dynamic cluster analyses revealed 2 replicable patterns of outcome: one for responders (n = 30) and one for partial responders (n = 20). Partial responders, compared with responders, tended to have more severe pretreatment numbing symptoms and greater anger about their RTC, along with lower global levels of functioning, greater pain severity and interference, and greater depression and were more likely to be taking psychotropic medications. Responders and partial responders did not differ in homework adherence, number of sessions attended, therapist effects, or stressors occurring during therapy or in the presence or absence of RTC-related litigation. Implications for enhancing treatment outcome are discussed.