Patient adherence predicts outcome from cognitive behavioral therapy in obsessive-compulsive disorder.

Cognitive-behavioral therapy consisting of exposure and response prevention (EX/RP) is an effective treatment for obsessive-compulsive disorder (OCD; American Psychiatric Association, 2007). However, only about half of patients who receive EX/RP achieve minimal symptoms (Simpson, et al., 2008; Simpson, Huppert, Petkova, Foa, & Liebowitz, 2006). Treatment outcome might be improved by developing more personalized care (Insel, 2009). One approach to personalized care is to identify factors that interfere with EX/RP outcome, develop interventions to address these factors, and provide these interventions to the individuals who need them. One factor thought to affect EX/RP outcome is whether patients adhere to the treatment procedures. Specifically, EX/RP therapists help patients face feared situations (“exposures”) to promote habituation to the anxiety that these situations trigger. Patients are asked to refrain from avoidance behaviors and rituals (“response prevention”) in order to break the connection between rituals and anxiety relief. Together, these procedures help disconfirm patients’ irrational beliefs. Therapists practice these steps with patients in session and assign specific exercises for between-session practice. Adherence with between-session assignments is thought to be critical for good outcome because repeated practice in different contexts is theorized to be essential to the emotional processing of the fear structure (Foa & Kozak, 1986; Kozak & Foa, 1997). Some studies suggest that patient adherence to EX/RP procedures is associated with treatment outcome (Abramowitz, Franklin, Zoellner, & DiBernardo, 2002; De Araujo, Ito, & Marks, 1996; Tolin, Maltby, Diefenbach, Hannan, & Worhunsky, 2004). However, Woods, Chambless, and Steketee (2002) found no significant relationship between EX/RP outcome and patient homework adherence. Unfortunately, patient adherence was assessed differently across these studies, none of the adherence measures has demonstrated validity or reliability, and some studies did not measure patient adherence prospectively. Thus, the effect of patient EX/RP adherence on treatment outcome has yet to be adequately examined. To address this significant gap, the current study examined the relationship between patient adherence to between-session assignments and treatment outcome in 30 adults with OCD who received EX/RP as part of a clinical trial. We used the Patient EX/RP Adherence Scale (PEAS) to prospectively assess adherence with between-session assignments because of its excellent inter-rater reliability and good construct validity (Simpson, Maher, et al., 2010). We hypothesized that patient adherence to between-session EX/RP assignments would be inversely associated with post-treatment OCD severity. We also examined whether early patient adherence predicted post-treatment OCD severity. Finally, we explored the relationship between patient adherence and other variables that predicted outcome in this sample.