The largest effectiveness study of ERP included 110 patients
treated on a fee-for-service hasis in an outpatient setting (37).
Treatment included 3 weeks of daily 2-hour ERP sessions. No
patients were excluded for reasons of age, comorhidity, previous
treatment failure, or medical problems. In fact, one-half of
the sample had comorbid Axis I or Axis II diagnoses, and 61 %
were also using serotonergic medication. Patients were only
excluded from the study if they were suffering from active
psychosis, substance abuse, or suicidal ideation (all these conditions
are contraindications for ERP in any setting; 38). An
intent-to-treat analysis indicated considerable improvement:
mean Y-BOCS scores improved from 26.79, SD 4.89, to
11.81, SD 7.30. This is equivalent to a 60% reduction in OCD
symptoms. This study suggests that the effects of ERP extend
beyond the highly selected patient samples treated in research
studies.