How Effective Are Medications for Obsessive-Compulsive Disorder?

What you need to know

• Medications like SSRIs and clomipramine help reduce symptoms of obsessive-compulsive disorder (OCD) compared to placebo pills.
• The benefits of these medications may be overestimated due to issues with how some studies were conducted and reported.
• Clomipramine appears to be more effective than SSRIs for OCD symptoms, even after accounting for study quality issues.

What is obsessive-compulsive disorder?

Obsessive-compulsive disorder (OCD) is a mental health condition that affects about 2% of people at some point in their lives. People with OCD experience persistent, intrusive thoughts, images, or urges (obsessions) that cause anxiety or distress. To try to relieve this distress, they feel compelled to perform certain behaviors or mental acts repeatedly (compulsions).

For example, someone might have intrusive thoughts about germs and contamination, leading them to wash their hands excessively. Or they may have distressing thoughts about harm coming to loved ones, causing them to repeatedly check that doors are locked. These obsessions and compulsions can significantly interfere with daily life and functioning.

How is OCD typically treated?

The main treatments recommended for OCD are:

1. Cognitive-behavioral therapy (CBT), particularly a type called exposure and response prevention
2. Medications called selective serotonin reuptake inhibitors (SSRIs)
3. A combination of CBT and medication

SSRIs are a type of antidepressant medication that increases levels of serotonin in the brain. Common SSRIs prescribed for OCD include fluoxetine, sertraline, paroxetine, and fluvoxamine.

Another medication sometimes used is clomipramine. It was the first medication found to be effective for OCD. However, it tends to have more side effects than SSRIs, so it’s usually not the first choice for treatment.

What did this study examine?

This study looked at the results of many clinical trials testing medications for OCD. The researchers wanted to understand:

1. How effective are these medications compared to placebo pills?
2. Does the quality of the studies affect the results?
3. Are there signs that positive results are more likely to be published, potentially skewing our understanding?

To investigate this, they conducted a systematic review and meta-analysis. This means they carefully searched for all relevant studies, assessed their quality, and combined their results statistically.

What did the study find?

Overall effectiveness

The analysis included 21 studies with a total of 4,102 participants. Overall, it found that OCD medications reduced symptoms more than placebo pills. The average difference was about 4.2 points on a common OCD symptom rating scale (the Yale-Brown Obsessive Compulsive Scale).

This represents a “medium” effect size in statistical terms. While noticeable, it’s unclear if this average change would make a big difference in most patients’ daily lives. Some patients likely experienced larger benefits, while others may have had little to no improvement.

Clomipramine vs. SSRIs

Interestingly, the older medication clomipramine appeared more effective than SSRIs. This remained true even after the researchers accounted for differences in study quality.

However, the authors note that clomipramine tends to have more side effects than SSRIs. So this finding doesn’t necessarily mean clomipramine should be used as the first treatment choice. The balance of benefits and risks needs to be considered for each patient.

Issues with study quality

Many of the clinical trials had some problems with how they were designed or conducted. Only 4 out of 21 studies were judged to have a low risk of bias. The rest had either some concerns or a high risk of bias.

Common issues included:

• Not clearly describing how patients were randomly assigned to medication or placebo groups
• Not stating if they had a pre-specified plan for analyzing the results
• Not including all participants in the final analysis (e.g., excluding those who dropped out early)

Importantly, studies with a higher risk of bias tended to show larger benefits from the medications. This suggests the true effectiveness may be somewhat lower than the overall results indicate.

Publication bias

The researchers also found evidence of publication bias. This means positive results were more likely to be published than negative ones.

Using statistical methods to estimate the impact of this bias, they found it likely inflated the apparent effectiveness of the medications. After accounting for publication bias, the estimated benefit of medications was smaller.

What are the implications?

This study highlights several important points for patients, clinicians, and researchers to consider:

1. Medications do appear to help many people with OCD, but their effects may be more modest than previously thought.

2. The benefits seen in published studies may be somewhat inflated due to issues with study quality and selective publishing of positive results.

3. Older studies tended to show larger effects than more recent ones. This could be because:

   • Newer studies may have better methods that give more accurate (but smaller) results
   • Early studies may have included patients who were easier to treat
   • The placebo response may have increased over time

4. While clomipramine seems more effective than SSRIs, its increased side effects mean it isn’t automatically the best choice. Treatment decisions should be individualized.

5. There’s a need for new, high-quality clinical trials of OCD medications. These could give us a clearer picture of their true effectiveness and help identify which patients are most likely to benefit.

6. Patients should have realistic expectations about medication benefits. While helpful for many, medications alone may not lead to complete symptom relief for most people with OCD.

Conclusions

• Medications like SSRIs and clomipramine do help reduce OCD symptoms for many patients.
• However, their effectiveness may be somewhat overestimated in the current medical literature.
• The older medication clomipramine appears more effective than SSRIs, but also has more side effects.
• There’s a need for new, rigorously-designed studies to better understand the true benefits and limitations of medications for OCD.