How common is difficult-to-treat or “treatment-resistant” panic disorder?

We often talk and read about difficult-to-treat (so called “treatment-resistant”) depression. But we have not paid enough attention to difficult-to-treat panic disorder. To some extent, we may underestimate how common it is for panic disorder to fail to respond, have only a partial response, have residual impairment, or have relapse or recurrence. This is true even with…