Evidence-based guidelines for interpretation of the Panic Disorder Severity Scale.
BACKGROUND
The Panic Disorder Severity Scale (PDSS) is promising to be a standard global rating scale for panic disorder. In order for a clinical scale to be useful, we need a guideline for interpreting its scores and their changes, and for defining clinical change points such as response and remission.


METHODS
We used individual patient data from two large randomized controlled trials of panic disorder (total n=568). Study participants were administered the PDSS and the Clinical Global Impression (CGI)--Severity and --Improvement. We applied equipercentile linking technique to draw correspondences between PDSS and CGI-Severity, numeric changes in PDSS and CGI-Improvement, and percent changes in PDSS and CGI-Improvement.


RESULTS
The interpretation of the PDSS total score differed according to the presence or absence of agoraphobia. When the patients were not agoraphobic, score ranges 0-1 corresponded with "Normal," 2-5 with "Borderline," 6-9 with "Slightly ill," 10-13 with "Moderately ill," and 14 and above with "Markedly ill." When the patients were agoraphobic, score ranges 3-7 meant "Borderline ill," 8-10 "Slightly ill," 11-15 "Moderately ill," and 16 and above "Markedly ill." The relationship between PDSS change and CGI-Improvement was more linear when measured as percentile change than as numeric changes, and was indistinguishable for those with or without agoraphobia. The decrease by 75-100% was considered "Very much improved," that by 40-74% "Much improved," and that by 10-39% "Minimally improved."


CONCLUSIONS
We propose that "remission" of panic disorder be defined by PDSS scores of five or less and its "response" by 40% or greater reduction.
Furukawa
Toshi A
TA
Department of Psychiatry and Cognitive-Behavioral Medicine, Nagoya City University Graduate School of Medical Sciences, Mizuhocho, Mizuho-ku, Nagoya 467-8601, Japan. furukawa@med.nagoya-cu.ac.jp
Katherine Shear
M
M
Barlow
David H
DH
Gorman
Jack M
JM
Woods
Scott W
SW
Money
Roy
R
Etschel
Eva
E
Engel
Rolf R
RR
Leucht
Stefan
S
D000328:Adult; D000379:Agoraphobia / Q000145:classification / Q000175:diagnosis / Q000523:psychology / Q000628:therapy; D000929:Antidepressive Agents, Tricyclic / Q000627:therapeutic use; D015928:Cognitive Behavioral Therapy; D003131:Combined Modality Therapy; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D007099:Imipramine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D016584:Panic Disorder / Q000145:classification / Q000175:diagnosis* / Q000523:psychology / Q000628:therapy; D010552:Personality Assessment / Q000706:statistics & numerical data*; D017410:Practice Guidelines as Topic; D011594:Psychometrics / Q000706:statistics & numerical data; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D016896:Treatment Outcome
D000929:Antidepressive Agents, Tricyclic; D007099:Imipramine