A second major change was that we included a "second chance" diagnostic stem question (SC20a) for respondents who denied SC20. This was an idea first proposed by Ken Kendler. The wording in this question was developed based on an initial suggestion of Dan Stein. This second chance question focuses on the most common psycho-physiological symptoms of panic and is designed to deal with people whose schema for a panic attack is organized around the rapid onset of physiological symptoms rather than the rapid onset of un-triggered fear. Our clinical reappraisal studies in the U.S. show that about one out of every six community cases of panic are missed by the first stem question and picked up by the second.

PD1a-p. These questions are virtually identical to those in earlier versions of CIDI. The "second chance" question for PD1k, PD1l, was proposed by Bill Eaton.

PD5-8. This series is asked of R's who report only one lifetime attack. While they cannot meet criteria for panic disorder (which requires multiple attacks), we were interested in dating the age of the attack in order to allow analysis to be done to study the predictors of progression from a first attack to multiple attacks.

PD8. Pilot studies showed that respondents have difficulty grasping the idea of an un-triggered attack. This rather long question, which begins with three declarative sentences, was our solution.

PD10b-c. Questions about 12-month persistence were included in all the diagnostic sections of the revised CIDI. Most sections have a single question equivalent to PD10b, while sections that deal with discrete events, like panic and intermittent explosive disorder, also ask about number of these events.

PD11-12. Questions about lifetime course of illness were also included in all the diagnostic sections. Most sections include a question like PD12, while sections that deal with discrete events, like panic and intermittent explosive disorder, also have questions like PD11.

PD13-13d. This series in included to operationalize the DSM-IV requirement of a month persistent worry or avoidance. This criterion is quite complicated, requiring multiple questions to assess it. As the questions are functional equivalents, respondents were skipped after the first positive response.

PD17-119. Note that we ask about number of lifetime attacks in each of the three types of situations even though we are only interested in "out of the blue" attacks for purposes of assessing panic disorder. Pilot studies showed that respondents were sometimes confused when we made the distinction among the three types of attacks and then never asked about two of the three. Gathering basic information about the other two types of attacks resolved this confusion.

PD36, 37b. Note that the 12-month persistence questions were repeated for "out of the blue" attacks. Similarly for PD16b.

PD40-43. These questions were developed in collaboration with Kathy Shear to represent a structured equivalent of items in Panic Disorder Severity Scale (Houck et al., 2002). Similarly PD16c-d.

PD44-65.1. These questions are identical to those included at the end of each diagnostic section. See commentary on the Depression section for a discussion of these questions.