Comorbidity as a predictor of symptom change after treatment in combat-related posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) is a difficult condition to treat, and existing studies show considerable variability in outcome. Investigations of factors that influence outcome have the potential to inform alternate treatment approaches to maximize benefits gained from interventions for the disorder. Because PTSD is commonly associated with comorbidity, it is important to investigate the influence of comorbidity on symptom change after treatment. This article examines pretreatment and 9-month follow-up data for 134 Australian Vietnam veterans who attended a treatment program for combat-related PTSD. A series of analyses were conducted to investigate the influence of the comorbid factors of anxiety, depression, anger, and alcohol use on PTSD symptom change after treatment. Analyses identified anger, alcohol, and depression as significant predictors of symptom change over time, independent of the effect of initial PTSD severity. Further analyses indicated that anger at intake was the most potent predictor of symptom change. Further investigations of anger as an influence on symptom change after treatment of combat-related PTSD is recommended.