The Effect of Sleep Disorders, Sedating Medications, and Depression on Cognitive Processing Therapy Outcomes: A Fuzzy Set Qualitative Comparative Analysis

Cognitive processing therapy (CPT) for posttraumatic stress disorder (PTSD) is an effortful process requiring engagement in cognitive restructuring. Sleep disorders may lead to avoidance of effortful tasks and cognitive performance deficits. We explored whether sleep disorders, as assessed by polysomnography, were consistently associated with treatment response in combination with other factors. This study included 32 U.S. veterans who were examined both before and after CPT for combat-related PTSD. We employed a novel, case-comparative technique, fuzzy set qualitative comparative analysis (fsQCA), to identify combinations of fuzzy and crisp factors (recipes) that achieve a clinically significant outcome. Approximately one-quarter of cases experiencing clinically significant change were either (a) Vietnam era veterans without sedating medications, moderate sleep disordered breathing, and severe depression; or (b) non-Vietnam era veterans with sedating medications and without severe periodic limb movements (or significant periodic limb movement arousals). Recipes involving the absence of the relevant sleep disorder were associated with the highest coverage values. These results using fsQCA (a) provide valuable information about the heterogeneity of CPT response and (b) suggest that sleep disorders are important factors to consider in theoretical discussions of who responds to CPT for PTSD.