Exposure and response prevention (ERP) is the first-line psychological treatment for obsessive compulsive disorder (OCD). Recent research shows that the Bergen 4-day Treatment (B4DT), which is a concentrated ERP program, can be very effective. However, this intensive format has not been widely implemented, and it is unclear whether positive outcomes are unique to B4DT, or whether a similar intensive ERP program (not based on B4DT) is equally effective. We examined short- and long-term outcomes of the Melbourne Intensive Treatment-OCD (MIT-O) program, an out-patient intensive ERP program for OCD involving an intensive phase of four full-day sessions conducted over two weeks, and a supportive 21-day phase involving self-directed tasks and twice-a-week check-in calls with the therapy team. Participants were 21 individuals with OCD. The severity of OCD, depression, anxiety, stress, obsessive beliefs, and emotion regulation difficulties were assessed at four time points (pre-treatment, post-treatment, 6-month, and 12-month follow-up). Results showed a large and significant decrease in OCD and obsessive beliefs at post-treatment. These improvements were maintained at 12-month follow-up. Using international consensus criteria for treatment response, almost all participants (90.5%) showed at least partial treatment response and one-third were in remission at the final assessment. These results showed that the MIT-O program was effective, but post-treatment and 12-month remission rates were somewhat less favourable than previously published results from the B4DT program. Nevertheless, the MIT-O post-treatment outcomes were comparable to other CBT programs for OCD and should be considered when other longer term treatment formats such as in-patient treatments are not feasible.

1. (1) To evaluate the effectiveness of an intensive exposure and response prevention program in reducing obsessive compulsive disorder (OCD) symptoms.

2. (2) To examine the long-term maintenance of treatment gains at 6-month and 12-month follow-up assessments.

3. (3) To report the treatment response rate and remission outcomes achieved through the intensive format.

4. (4) To consider the broader implementation of intensive exposure and response prevention programs as an alternative format for OCD treatment.