A 35-year-old man with a 6-year history of OCD presents to the clinic after 12 weeks of treatment with sertraline 200 mg daily. He reports that his obsessions about contamination and compulsive washing rituals have reduced by only 10–15%, and he continues to spend 4–5 hours daily on compulsions. He has good adherence to medication and denies significant adverse effects. His Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score is 32 (indicating moderate-to-severe OCD). He has never received cognitive-behavioural therapy (CBT) or exposure and response prevention (ERP). What is the most appropriate next step in management?

Explanation

## Treatment-Resistant OCD: Definition and Approach **Key Point:** Treatment-resistant OCD is defined as inadequate response (<25% reduction in Y-BOCS) after 8–12 weeks of an adequate dose of a first-line SSRI. This patient meets criteria for treatment resistance (only 10–15% improvement on sertraline 200 mg for 12 weeks). **High-Yield:** The most effective next step in treatment-resistant OCD is to combine pharmacotherapy with evidence-based psychotherapy (CBT/ERP), rather than medication adjustment alone. CBT/ERP has Level 1 evidence for OCD and should be offered to all patients, especially those with inadequate pharmacological response. ## Management Algorithm for Treatment-Resistant OCD ```mermaid flowchart TD A[OCD on SSRI 8-12 weeks]:::outcome --> B{Response ≥25% Y-BOCS reduction?}:::decision B -->|Yes| C[Continue SSRI, optimize dose]:::action B -->|No| D[Treatment-resistant OCD]:::urgent D --> E{Has patient received CBT/ERP?}:::decision E -->|No| F[Initiate CBT/ERP + continue SSRI]:::action E -->|Yes| G{Adequate trial of ERP?}:::decision G -->|No| H[Optimize ERP intensity/frequency]:::action G -->|Yes| I[Switch/augment pharmacotherapy]:::action I --> J{Options}:::decision J -->|Try clomipramine| K[Clomipramine 100-250 mg]:::action J -->|Augment SSRI| L[Add antipsychotic or increase dose]:::action ``` ## Why CBT/ERP + Pharmacotherapy Is Correct 1. **Evidence hierarchy:** CBT/ERP is Level 1 evidence for OCD and has demonstrated superiority to medication alone in multiple RCTs and meta-analyses. 2. **Patient has not received psychotherapy:** This is the first opportunity to offer the gold-standard psychological intervention; it should be attempted before further medication changes. 3. **Combination approach:** SSRI + CBT/ERP produces superior outcomes compared to either modality alone, with response rates of 60–80% in treatment-resistant cases. 4. **Y-BOCS score indicates moderate-to-severe disease:** A score of 32 warrants intensive treatment, and CBT/ERP is the most intensive evidence-based psychological intervention. **Clinical Pearl:** The patient's lack of prior exposure therapy is a critical gap. Many patients initially labeled "treatment-resistant" respond well once adequate ERP is introduced, even on the same medication dose. ## Comparison of Next-Step Options | Option | Rationale | Evidence | Timing | |--------|-----------|----------|--------| | **Add CBT/ERP** | First-line for treatment-resistant OCD; patient has not yet received it | Level 1 (RCTs, meta-analyses) | Initiate immediately alongside SSRI | | Switch to clomipramine | Second-line SSRI alternative; reasonable if CBT/ERP unavailable or refused | Level 1 but second-line | Consider after CBT/ERP trial or if psychotherapy unavailable | | Increase sertraline to 300 mg | Exceeds FDA-approved maximum (200 mg); limited evidence for higher doses | Level 3 (expert opinion) | Not recommended; dose already adequate | | Add risperidone | Augmentation strategy for SSRI non-response; but should follow CBT/ERP trial first | Level 2 (open trials) | Reserved for after CBT/ERP optimization | **Mnemonic:** **CBT First, Then Meds Adjust** — In treatment-resistant OCD, always optimize psychotherapy before escalating pharmacotherapy. ## Implementation of CBT/ERP **High-Yield:** Effective ERP for contamination OCD involves: - **Exposure:** Deliberate contact with feared contaminants (e.g., touching doorknobs, soil) without avoidance. - **Response Prevention:** Resisting the urge to wash, clean, or ritualize after exposure. - **Frequency:** Typically 1–2 sessions per week for 12–16 weeks; may require intensive formats (e.g., 5 days per week) for severe cases. - **Therapist:** Should be trained in OCD-specific CBT/ERP (not general CBT). [cite:Harrison 21e Ch 389; American Psychiatric Association Practice Guideline for OCD]