The Panic-Associated Symptom Scale : measuring the severity of panic disorder Argyle N, Deltito J, Allerup P, Maier W, Albus M, Nutzinger D, Rasmussen S, Ayuso JL, Bech P. The Panic-Associated Symptom Scale: measuring the severity of panic disorder. Acta Psychiatr Scand 1991: 83: 20-26.
The Panic-Associated Symptom Scale (PASS) is presented as a new measurement of the severity of the core symptoms of panic disorder. This first description addresses the rationale for its design and its scoring, score distributions, test-retest reliability, correlations within the PASS and with other scales, principal component structure, and response to drug therapy. Data are presented from a large study group of patients with panic disorder ( n = 1168). Problems in measuring panic disorder are discussed.
Since its introduction in DSM-I11 (l),panic disorder has been the focus of great research interest among both laboratory investigators and clinicians. It has again been accepted in DSM-I11 as a nosological entity. Perhaps because the limits of panic disorder as a syndrome remain unclear, there has as yet been no published scale for measuring its severity. However, such a scale is needed to facilitate reporting and comparison between different samples and treatment responses. Panic disorder has been found to have significant and frequent co-morbidity with all the anxiety states and with depression (2,3). The nature of these overlaps remains disputed. DSM-111-R accepts the dominant view among psychopharmacologists in the United States that panic attacks are primary and anticipatory anxiety and phobic avoidance appear secondarily. Behaviorists such as Marks (4) argue for a more important role for phobic avoidance and phobic situations. The relationship with depression and depressive illness is even more unclear. Some 30-50% of subjects with panic disorder meet criteria 20
N. Argyle’*’, J. Deltito’, P. Allerup3, W. Maier4, M. Albus’, D. Nutzinger6, S.Rasmussen3, J. L. Ayuso7, P. Bech3
’
Cornell University Medical College, Westchester Division, New York, New York, * Department of Physiology, Maharishi International University, Fairfield, Iowa, USA, Department of Psychiatry, Frederiksborg General Hospital, Hillernd, Denmark, Psychiatrische Klinik und Poliklinik, Klinikum der Johannes Gutenberg Universitat, Mainz, Psychiatrische Klinik und Poliklinik, Nervenklinik der Universitat Munchen, Munich, Federal Republic of Germany, Psychiatrische Universitatsklinik, Vienna, Austria, Department of Psychiatry, Complutense University, Madrid, Spain
Key words: panic disorder; agoraphobia Dr. Nick Argyle, Physiology Dept, M.I.U., Fairfield, IA 52556, USA Accepted for publication July 28, 1990
for DSM-I11 major depressive episode (3, 5). DSM111-R now allows both diagnoses to be made. At present the view of many clinicians is that panic disorder does exist and the phobic symptoms commonly seen are secondary to or, at least, clearly related to the panic attacks, i.e., patients avoid going out because they fear having panic attacks. No such consensus exists on the place of depression, which may be demoralization in response to panic or may be part of a primary depressive illness. Similar problems exist with the role of generalized, nonphobic anxiety (6). Therefore, although the symptoms relating to agoraphobic avoidance must be included in a measure of the severity of panic disorder, it would be premature to include those related to generalized anxiety and depression. Several authors find that a high percentage of patients also have social and monophobias (2, 7). In particular, social phobia overlaps with panic disorder. The patient may be afraid of being embarrassed or humiliated by poor social performance and fear having a panic in social situations. He may
Panic-associated symptom scale also experience even more embarrassment when he does have a panic attack. Some simple phobias, such as flying phobia, may be seen as belonging to the agoraphobia spectrum and also having the early onset, specific nature, and inevitable association with anxiety that characterizes other simple phobias. The currently conceptualized exclusive association between panic disorder and agoraphobia may well need to be expanded to include other phobias. Although DSM-111-R accepts spontaneity as a quintessential feature of panic disorder, as would be expected from a biological illness, a severity scale cannot be restricted to spontaneous panic attacks. Spontaneity is contrasted with the almost invariable association with specific situations seen in a classical monophobia. Phobic anxiety and panic attacks associated with agoraphobia are often less closely tied - patients do not know if they will panic or not in a given situation. Many patients have spontaneous attacks in their past history but mainly or only situational attacks in their current pathology - this is included as panic disorder. A further concern with categorizing a panic attack as spontaneous is the role of cognitions and internal physical stimuli in the triggering of such attacks. Evidence from cognitive and behavioral studies increasingly suggests that the number of attacks that are purely spontaneous with no such triggers may be quite small (8, 9). One problem for a measure of panic disorder severity is the changing nature of the disorder. Early in the disorder, spontaneous panics are seen, which are followed by anticipatory anxiety and subsequently situational panic attacks and phobic avoidance. This is the pattern dzscribed by Klein and others (10). However the course fluctuates both from day to day and month to month. This can reflect the frequency with which patients attempt to re-enter phobic situations, leading to increased panic attacks. In clinical practice most patients present with both panic attacks and phobic avoidance. Earlier stages of illness when only one or the other is present are less likely to be seen. A possible late stage of illness when only phobic avoidance is present is also less seen. This article presents a new measure of the core symptoms of panic disorder, which are, as reflected in the DSM-111-R definition, panic attacks, anticipatory anxiety, phobic anxiety and avoidance. Material and methods
Panic-Associated Symptom Scale
The Panic-Associated Symptom Scale (PASS) measures the severity of the core symptoms of panic disorder. As this is a new scale, attention must be paid to its face validity, item selection, item definition
and scoring. It is not a diagnostic scale and does not include items such as insomnia, poor concentration, generalized anxiety and depressed mood. Many such symptoms are commonly found in patients with panic disorder but have no specific significance for a panic disorder diagnosis and could well be associated with a concurrent diagnosis of another anxiety state or depressive illness. The PASS is therefore not analogous to the well-known Hamilton Rating Scales for Anxiety and Depression, which do include Table 1. PASS core
> 3 symptom panic attacks Situational (SiPA)
Score
0
Number in last week =
0 1 2 3
1
2-7 8t Average intensity =
0 1 2 3
0-3
4-6 7-9 10 Spontaneous (SpPA)
0
Number in last week =
0 1 2 3
1
2-7 8t
Item code
PASS 1
PASS 2
PASS 3
~~
Average intensity =
7-9 10
0 1 2 3
0 1-8 8t
0 1 2
PASS 5
0-3
0 1 2
PASS 6
0-3
4-6
Limited symptom attacks (LSA) Total number in last week =
Average intensity =
4-6 7-10 Anticipatory anxiety (AA) Average % of waking hours in last week =
Average intensity =
0 1-30 3 1-60 6 1-90 91-100 0-3
4-6 7-9 10 Phobia score (PSI
Overall phobia score =
0 1-2 3-4
0 1 2 3
PASS 4
PASS 7
4 0 1 2 3
5-6
0 1 2 3
7-8 9-10
4 5
PASS 8
PASS 9
Total score range is 0-28 On 0-10 scales: 0 = zero, 2 = mild, 5 = moderate, 8 = marked, 10 =extreme
21
Argyle et al.
such items. In view of the daily fluctuations in panic disorder symptoms, the score is taken from an assessment of the previous week’s symptoms. The weights and cut-off points for the individual scale items and components were calculated from a body of data collected in Cambridge by the first author, including patients in general practice, psychiatric outpatients and day patients, and patients referred to, but not entering, the clinical trial described below. This preliminary scoring system was based on the consensus of several clinicians and researchers and the spread of the data. This scoring system is tested on the larger patient population presented here. The item scores are displayed in Table 1. There are five core symptoms: situational panic attacks (SiPA), spontaneous panic attacks (SpPA), limited symptom attacks (LSA), anticipatory anxiety (AA) and phobia score (PS). It was decided to weight the 5 items approximately in the ratio 1 : 1 : 0.5 : 1 : 1.5; this was the consensus on the relative amounts of distress caused by these symptoms. This weighting gives an equal balance between panic attacks (including situational, spontaneous, and limited) and anticipatory and phobic anxiety and avoidance. Panic attacks
The first 2 items are situational panic attacks and spontaneous panic attacks. Situational is defined as occurring in or when just about to enter a situation known from past experience to be associated with panic attacks. All nonsituational attacks are labelled spontaneous attacks, which therefore include attacks that might be triggered by cognitions or physical stimuli but do not occur in or just before entering phobic situations. Each type of attack has 2 components -frequency and intensity. These component scores are added rather than multiplied to avoid too large a range of scores and to represent the clinical impression that the distress caused by the intensity of individual attacks is partly independent of frequency, at least within a l-week period. Panic attacks are distinct from most other symptoms in that they have an all-or-nothing quality, and patients’ distress levels show a quantum leap from no panic attacks to any panic attacks at all. The range of frequency data is typically large in clinical studies and a logarithmic scale of number of panic attacks is often more appropriate for statistical analysis than a raw score. The 4-category scale of 0, 1,2-7, 8 or more panics per week was based partly on the advice of Carl Lewis, M.D., Ph.D. of the Upjohn Company on the basis of extensive experience in studying the distribution of panic attacks’ frequency in previous clinical trials. The intensity was scored by patients on a scale of 0-10 with 10 being “extreme anxiety - as bad as could be 22
imagined”. This was transformed to 0-3, 4-6, 7-9, and 10; 10 having a separate category gives recognition to the fact that panic attacks are often characterized by such extreme anxiety. The duration of an attack is not scored because: attacks tend to have a fairly typical length (1 l), intensity seems more important clinically and patients may not be able to determine clearly how long an attack lasts; onset is sudden but the end of an attack is often a gradual decline to some level of residual anxiety or a level of baseline anxiety already there before the attack. Some authors would argue that panic attacks and anxiety exist along a continuum (12). Argyle & Roth (1 1) found that although there were overlapping symptoms, the sudden onset, high number of symptoms and degree of anxiety did distinguish panic attacks. In practice, patients report distinct attacks and often remember them for long periods. Limited symptom attacks
Although not widely reported in the literature, panic disorder patients recognize and report limited symptom attacks (LSA) (13). They are characterized by having fewer symptoms than polysymptomatic panic attacks, but may have just as high an intensity. They are particularly clinically relevant during the course of treatment after full panic attacks have ceased. Weighting them relatively less than full panic attacks, this item includes both spontaneous and situational LSA, and the range of scores is appropriately reduced. Anticipatory anxiety
This refers to anxiety associated with anticipating both panic attacks and phobic situations associated with panic attacks. There are 2 components - average percentage of waking hours and intensity on a 0-10 scale as for panic attacks. Once again, the components are added. Phobias
This is scored on a single scale that is a global score of how distressing or restricting phobias have been. It therefore includes both phobic anxiety and avoidance. Ideally, this should be restricted to phobias associated with panic attacks. However, operationally this is difficult. Even if a patient says his agoraphobia is not due to the panic attacks, most clinicians would think they were connected. For social phobia there may be mixed attribution as already noted. As this is not a diagnostic scale and the great majority of phobias seen are panic-associated and there is a current dispute over the primacy of panic
Panic-associated symptom scale
attacks or phobic avoidance, it seems simplest to use a global phobia scale without prejudice as to the nature of the phobia. One concern was that the overall phobia score would in fact include both situational panic attacks and anticipatory anxiety, overvaluing these components. Our experience was that patients could separate these out. Analysis of the correlation between items’ scores within the PASS would confirm or refute this.
Patient-rated Global Improvement (PGI), Physician-rated Global Improvement (PhGI), and global work and social disability scale (DIS). Results Distribution of item scores and PASS total
The distribution for PASS total at baseline is given in Fig. 1. It is close to a normal distribution. Table 2 gives the distribution of item scores at baseline. The uneven distribution of PASS 1 and PASS 2 is caused by a large number, 39%, having no situational attacks (PASS 1 = 0). Considering the mean scores, at baseline the difference between SiPA (PASS 1 plus PASS 2) and SpPA (PASS 3 plus PASS 4)is 50%, becoming less than 30% at weeks 3 and 8. The contribution of LSA increases from 50% of SiPA at baseline to approximate that of either SiPA or SpPA. Within each of SiPA, SpPA and LSA the contribution of frequency and severity remains within 25 % of each other at any given week. Anticipatory anxiety (AA), PASS 7 plus PASS 8, is close to phobia score (PS), (PASS 9). SiPA plus SpPA plus LSA is very close to AA plus PS (6.3 and 6.2) at baseline. As would be expected clinically, AA contributes relatively more by week 8 than SiPA or SpPA. PS becomes an even greater percentage of the total score by week 8 (38%).
Study group
The PASS was applied to a population enrolled in the Cross-National Collaborative Panic Study phase I1 (14). A comprehensive account is currently under review. This trial was an outpatient, doubleblind comparison of imipramine, alprazolam and placebo over 8 weeks. A total of 1168 patients from 12 centers were successfully screened and randomized into this study protocol. Patients, aged 18-65, met modified DSM-I11 criteria for panic disorder - a history of at least one spontaneous panic attack with 4 or more symptoms and at least one panic attack with 2 3 symptoms per week in the last 3 weeks; 61 % were female, average age, 34. Patients were excluded if they had any past history of seizures or psychosis, dementia or bipolar disorder, recent history of drug or alcohol abuse, obsessive-compulsive disorder, or inability to give up psychoactive medication or psychotherapy. Patients with current major depression were excluded unless this appeared after the onset of panic in this episode and was not clinically predominant, and not melancholic or psychotic. Other data collected at weekly visits included the Hamilton Rating Scale for Anxiety (HRSA), Hamilton Rating Scale for Depression (HRSD),
PASS item-item and total correlations
Table 3 gives the item-item and item-total score Pearson correlations at baseline. (The tables for weeks 3 and 8 are similar but with generally higher correlations. There are no significant differences between treatment groups.) The only item-item correlations at baseline above 0.5 are between frequency and intensity within one symptom. Cronbach’s alpha
Number 20 of patients
Mean = 12.4 SD = 4.74 Mcdian = 12 QILQ3 = 7 Skewness = 0 31 Kurtosis = - 0.25
150
100
50
2
4
6
8
10
12 PZSS
14
16
18
20
22
24
26
28
‘i0IC
Fig. 1. PASS total: distribution at baseline
23
Argyle et al. Table 2. Item distribution at baseline: number of subjects with each score (n= 1165)
Table 4. Correlation and concordance of PASS total with other clinical measures Concordance, gamma Baseline
Item scores Correlation with PASS Item
PASS 1 PASS 2 PASS 3 PASS 4 PASS 5 PASS 6 PASS 7 PASS 8 PASS 9
0
1
2
3
457 483 187 218 564 694 96 316 90
215 242 256 347 463 353 457 470 80
382 380 566 499 136 118 265 314 136
109 58 154 99
4
5 ~
-
-
248 62 235
-
HRSA total HRSD total DIS LTP PS PhGl PGI
96
Baseline
Week 3
Week 8
PASS
LTP
0.47 0.38 0.47 0.55 0.64 -
0.63 0.55 0.61 0.76 0.71 -0.62 -0.61
0.63 0.59 0.66 0.74 0.71 -0.68 -0.60
0.35 (0.019) 0.28 (0.020) 0.45 (0.024) 0.44 (0.019) 0.60(0.019) -
0.28 (0.021) 0.24 (0.022) 0.23 (0.0281 0.19(0.021)
-
-
~~
-
-
376 All correlations: P = 0.0001. ASE in parentheses LTP = log total panic attacks.
Table 3. Item-item and item-total correlations at baseline (Pearson r ) PASS 1 PASS2 PASS3 PASS4 PASS5 PASS6 PASS7 PASS8 PASS9
PASS 1 1 PASS 2 0.74 1 PASS 3 -0.03 -0.1 1 1 PASS 4 -0.10 -0.03 0.57 1 PASS 5 0.42 0.35 -0.08 -0.07 1 PASS 6 0.31 0.38 -0.06 0.03 0.68 PASS 7 0.13 0.19 0.17 0.24 0.11 PASS8 0.15 0.25 0.14 0 . 2 9 0 . 1 0 PASS 9 0.30 0.30 0.02 0.09 0.26 Total 0.60 0.63 0.32 0.40 0.50
Age and sex 1 0.15 0.24 0.26 0.54
1 0.62 0.18 0.59
1 0.23 0.62
1 0.63
All correlations >0.1 or
The Panic-Associated Symptom Scale (PASS) is presented as a new measurement of the severity of the core symptoms of panic disorder. This first description addresses the rationale for its design and its scoring, score distributions, test-retest reliability, correlations within the PASS and with other scales, principal component structure, and response to drug therapy. Data are presented from a large study group of patients with panic disorder ( n = 1168). Problems in measuring panic disorder are discussed.
Since its introduction in DSM-I11 (l),panic disorder has been the focus of great research interest among both laboratory investigators and clinicians. It has again been accepted in DSM-I11 as a nosological entity. Perhaps because the limits of panic disorder as a syndrome remain unclear, there has as yet been no published scale for measuring its severity. However, such a scale is needed to facilitate reporting and comparison between different samples and treatment responses. Panic disorder has been found to have significant and frequent co-morbidity with all the anxiety states and with depression (2,3). The nature of these overlaps remains disputed. DSM-111-R accepts the dominant view among psychopharmacologists in the United States that panic attacks are primary and anticipatory anxiety and phobic avoidance appear secondarily. Behaviorists such as Marks (4) argue for a more important role for phobic avoidance and phobic situations. The relationship with depression and depressive illness is even more unclear. Some 30-50% of subjects with panic disorder meet criteria 20
N. Argyle’*’, J. Deltito’, P. Allerup3, W. Maier4, M. Albus’, D. Nutzinger6, S.Rasmussen3, J. L. Ayuso7, P. Bech3
’
Cornell University Medical College, Westchester Division, New York, New York, * Department of Physiology, Maharishi International University, Fairfield, Iowa, USA, Department of Psychiatry, Frederiksborg General Hospital, Hillernd, Denmark, Psychiatrische Klinik und Poliklinik, Klinikum der Johannes Gutenberg Universitat, Mainz, Psychiatrische Klinik und Poliklinik, Nervenklinik der Universitat Munchen, Munich, Federal Republic of Germany, Psychiatrische Universitatsklinik, Vienna, Austria, Department of Psychiatry, Complutense University, Madrid, Spain
Key words: panic disorder; agoraphobia Dr. Nick Argyle, Physiology Dept, M.I.U., Fairfield, IA 52556, USA Accepted for publication July 28, 1990
for DSM-I11 major depressive episode (3, 5). DSM111-R now allows both diagnoses to be made. At present the view of many clinicians is that panic disorder does exist and the phobic symptoms commonly seen are secondary to or, at least, clearly related to the panic attacks, i.e., patients avoid going out because they fear having panic attacks. No such consensus exists on the place of depression, which may be demoralization in response to panic or may be part of a primary depressive illness. Similar problems exist with the role of generalized, nonphobic anxiety (6). Therefore, although the symptoms relating to agoraphobic avoidance must be included in a measure of the severity of panic disorder, it would be premature to include those related to generalized anxiety and depression. Several authors find that a high percentage of patients also have social and monophobias (2, 7). In particular, social phobia overlaps with panic disorder. The patient may be afraid of being embarrassed or humiliated by poor social performance and fear having a panic in social situations. He may
Panic-associated symptom scale also experience even more embarrassment when he does have a panic attack. Some simple phobias, such as flying phobia, may be seen as belonging to the agoraphobia spectrum and also having the early onset, specific nature, and inevitable association with anxiety that characterizes other simple phobias. The currently conceptualized exclusive association between panic disorder and agoraphobia may well need to be expanded to include other phobias. Although DSM-111-R accepts spontaneity as a quintessential feature of panic disorder, as would be expected from a biological illness, a severity scale cannot be restricted to spontaneous panic attacks. Spontaneity is contrasted with the almost invariable association with specific situations seen in a classical monophobia. Phobic anxiety and panic attacks associated with agoraphobia are often less closely tied - patients do not know if they will panic or not in a given situation. Many patients have spontaneous attacks in their past history but mainly or only situational attacks in their current pathology - this is included as panic disorder. A further concern with categorizing a panic attack as spontaneous is the role of cognitions and internal physical stimuli in the triggering of such attacks. Evidence from cognitive and behavioral studies increasingly suggests that the number of attacks that are purely spontaneous with no such triggers may be quite small (8, 9). One problem for a measure of panic disorder severity is the changing nature of the disorder. Early in the disorder, spontaneous panics are seen, which are followed by anticipatory anxiety and subsequently situational panic attacks and phobic avoidance. This is the pattern dzscribed by Klein and others (10). However the course fluctuates both from day to day and month to month. This can reflect the frequency with which patients attempt to re-enter phobic situations, leading to increased panic attacks. In clinical practice most patients present with both panic attacks and phobic avoidance. Earlier stages of illness when only one or the other is present are less likely to be seen. A possible late stage of illness when only phobic avoidance is present is also less seen. This article presents a new measure of the core symptoms of panic disorder, which are, as reflected in the DSM-111-R definition, panic attacks, anticipatory anxiety, phobic anxiety and avoidance. Material and methods
Panic-Associated Symptom Scale
The Panic-Associated Symptom Scale (PASS) measures the severity of the core symptoms of panic disorder. As this is a new scale, attention must be paid to its face validity, item selection, item definition
and scoring. It is not a diagnostic scale and does not include items such as insomnia, poor concentration, generalized anxiety and depressed mood. Many such symptoms are commonly found in patients with panic disorder but have no specific significance for a panic disorder diagnosis and could well be associated with a concurrent diagnosis of another anxiety state or depressive illness. The PASS is therefore not analogous to the well-known Hamilton Rating Scales for Anxiety and Depression, which do include Table 1. PASS core
> 3 symptom panic attacks Situational (SiPA)
Score
0
Number in last week =
0 1 2 3
1
2-7 8t Average intensity =
0 1 2 3
0-3
4-6 7-9 10 Spontaneous (SpPA)
0
Number in last week =
0 1 2 3
1
2-7 8t
Item code
PASS 1
PASS 2
PASS 3
~~
Average intensity =
7-9 10
0 1 2 3
0 1-8 8t
0 1 2
PASS 5
0-3
0 1 2
PASS 6
0-3
4-6
Limited symptom attacks (LSA) Total number in last week =
Average intensity =
4-6 7-10 Anticipatory anxiety (AA) Average % of waking hours in last week =
Average intensity =
0 1-30 3 1-60 6 1-90 91-100 0-3
4-6 7-9 10 Phobia score (PSI
Overall phobia score =
0 1-2 3-4
0 1 2 3
PASS 4
PASS 7
4 0 1 2 3
5-6
0 1 2 3
7-8 9-10
4 5
PASS 8
PASS 9
Total score range is 0-28 On 0-10 scales: 0 = zero, 2 = mild, 5 = moderate, 8 = marked, 10 =extreme
21
Argyle et al.
such items. In view of the daily fluctuations in panic disorder symptoms, the score is taken from an assessment of the previous week’s symptoms. The weights and cut-off points for the individual scale items and components were calculated from a body of data collected in Cambridge by the first author, including patients in general practice, psychiatric outpatients and day patients, and patients referred to, but not entering, the clinical trial described below. This preliminary scoring system was based on the consensus of several clinicians and researchers and the spread of the data. This scoring system is tested on the larger patient population presented here. The item scores are displayed in Table 1. There are five core symptoms: situational panic attacks (SiPA), spontaneous panic attacks (SpPA), limited symptom attacks (LSA), anticipatory anxiety (AA) and phobia score (PS). It was decided to weight the 5 items approximately in the ratio 1 : 1 : 0.5 : 1 : 1.5; this was the consensus on the relative amounts of distress caused by these symptoms. This weighting gives an equal balance between panic attacks (including situational, spontaneous, and limited) and anticipatory and phobic anxiety and avoidance. Panic attacks
The first 2 items are situational panic attacks and spontaneous panic attacks. Situational is defined as occurring in or when just about to enter a situation known from past experience to be associated with panic attacks. All nonsituational attacks are labelled spontaneous attacks, which therefore include attacks that might be triggered by cognitions or physical stimuli but do not occur in or just before entering phobic situations. Each type of attack has 2 components -frequency and intensity. These component scores are added rather than multiplied to avoid too large a range of scores and to represent the clinical impression that the distress caused by the intensity of individual attacks is partly independent of frequency, at least within a l-week period. Panic attacks are distinct from most other symptoms in that they have an all-or-nothing quality, and patients’ distress levels show a quantum leap from no panic attacks to any panic attacks at all. The range of frequency data is typically large in clinical studies and a logarithmic scale of number of panic attacks is often more appropriate for statistical analysis than a raw score. The 4-category scale of 0, 1,2-7, 8 or more panics per week was based partly on the advice of Carl Lewis, M.D., Ph.D. of the Upjohn Company on the basis of extensive experience in studying the distribution of panic attacks’ frequency in previous clinical trials. The intensity was scored by patients on a scale of 0-10 with 10 being “extreme anxiety - as bad as could be 22
imagined”. This was transformed to 0-3, 4-6, 7-9, and 10; 10 having a separate category gives recognition to the fact that panic attacks are often characterized by such extreme anxiety. The duration of an attack is not scored because: attacks tend to have a fairly typical length (1 l), intensity seems more important clinically and patients may not be able to determine clearly how long an attack lasts; onset is sudden but the end of an attack is often a gradual decline to some level of residual anxiety or a level of baseline anxiety already there before the attack. Some authors would argue that panic attacks and anxiety exist along a continuum (12). Argyle & Roth (1 1) found that although there were overlapping symptoms, the sudden onset, high number of symptoms and degree of anxiety did distinguish panic attacks. In practice, patients report distinct attacks and often remember them for long periods. Limited symptom attacks
Although not widely reported in the literature, panic disorder patients recognize and report limited symptom attacks (LSA) (13). They are characterized by having fewer symptoms than polysymptomatic panic attacks, but may have just as high an intensity. They are particularly clinically relevant during the course of treatment after full panic attacks have ceased. Weighting them relatively less than full panic attacks, this item includes both spontaneous and situational LSA, and the range of scores is appropriately reduced. Anticipatory anxiety
This refers to anxiety associated with anticipating both panic attacks and phobic situations associated with panic attacks. There are 2 components - average percentage of waking hours and intensity on a 0-10 scale as for panic attacks. Once again, the components are added. Phobias
This is scored on a single scale that is a global score of how distressing or restricting phobias have been. It therefore includes both phobic anxiety and avoidance. Ideally, this should be restricted to phobias associated with panic attacks. However, operationally this is difficult. Even if a patient says his agoraphobia is not due to the panic attacks, most clinicians would think they were connected. For social phobia there may be mixed attribution as already noted. As this is not a diagnostic scale and the great majority of phobias seen are panic-associated and there is a current dispute over the primacy of panic
Panic-associated symptom scale
attacks or phobic avoidance, it seems simplest to use a global phobia scale without prejudice as to the nature of the phobia. One concern was that the overall phobia score would in fact include both situational panic attacks and anticipatory anxiety, overvaluing these components. Our experience was that patients could separate these out. Analysis of the correlation between items’ scores within the PASS would confirm or refute this.
Patient-rated Global Improvement (PGI), Physician-rated Global Improvement (PhGI), and global work and social disability scale (DIS). Results Distribution of item scores and PASS total
The distribution for PASS total at baseline is given in Fig. 1. It is close to a normal distribution. Table 2 gives the distribution of item scores at baseline. The uneven distribution of PASS 1 and PASS 2 is caused by a large number, 39%, having no situational attacks (PASS 1 = 0). Considering the mean scores, at baseline the difference between SiPA (PASS 1 plus PASS 2) and SpPA (PASS 3 plus PASS 4)is 50%, becoming less than 30% at weeks 3 and 8. The contribution of LSA increases from 50% of SiPA at baseline to approximate that of either SiPA or SpPA. Within each of SiPA, SpPA and LSA the contribution of frequency and severity remains within 25 % of each other at any given week. Anticipatory anxiety (AA), PASS 7 plus PASS 8, is close to phobia score (PS), (PASS 9). SiPA plus SpPA plus LSA is very close to AA plus PS (6.3 and 6.2) at baseline. As would be expected clinically, AA contributes relatively more by week 8 than SiPA or SpPA. PS becomes an even greater percentage of the total score by week 8 (38%).
Study group
The PASS was applied to a population enrolled in the Cross-National Collaborative Panic Study phase I1 (14). A comprehensive account is currently under review. This trial was an outpatient, doubleblind comparison of imipramine, alprazolam and placebo over 8 weeks. A total of 1168 patients from 12 centers were successfully screened and randomized into this study protocol. Patients, aged 18-65, met modified DSM-I11 criteria for panic disorder - a history of at least one spontaneous panic attack with 4 or more symptoms and at least one panic attack with 2 3 symptoms per week in the last 3 weeks; 61 % were female, average age, 34. Patients were excluded if they had any past history of seizures or psychosis, dementia or bipolar disorder, recent history of drug or alcohol abuse, obsessive-compulsive disorder, or inability to give up psychoactive medication or psychotherapy. Patients with current major depression were excluded unless this appeared after the onset of panic in this episode and was not clinically predominant, and not melancholic or psychotic. Other data collected at weekly visits included the Hamilton Rating Scale for Anxiety (HRSA), Hamilton Rating Scale for Depression (HRSD),
PASS item-item and total correlations
Table 3 gives the item-item and item-total score Pearson correlations at baseline. (The tables for weeks 3 and 8 are similar but with generally higher correlations. There are no significant differences between treatment groups.) The only item-item correlations at baseline above 0.5 are between frequency and intensity within one symptom. Cronbach’s alpha
Number 20 of patients
Mean = 12.4 SD = 4.74 Mcdian = 12 QILQ3 = 7 Skewness = 0 31 Kurtosis = - 0.25
150
100
50
2
4
6
8
10
12 PZSS
14
16
18
20
22
24
26
28
‘i0IC
Fig. 1. PASS total: distribution at baseline
23
Argyle et al. Table 2. Item distribution at baseline: number of subjects with each score (n= 1165)
Table 4. Correlation and concordance of PASS total with other clinical measures Concordance, gamma Baseline
Item scores Correlation with PASS Item
PASS 1 PASS 2 PASS 3 PASS 4 PASS 5 PASS 6 PASS 7 PASS 8 PASS 9
0
1
2
3
457 483 187 218 564 694 96 316 90
215 242 256 347 463 353 457 470 80
382 380 566 499 136 118 265 314 136
109 58 154 99
4
5 ~
-
-
248 62 235
-
HRSA total HRSD total DIS LTP PS PhGl PGI
96
Baseline
Week 3
Week 8
PASS
LTP
0.47 0.38 0.47 0.55 0.64 -
0.63 0.55 0.61 0.76 0.71 -0.62 -0.61
0.63 0.59 0.66 0.74 0.71 -0.68 -0.60
0.35 (0.019) 0.28 (0.020) 0.45 (0.024) 0.44 (0.019) 0.60(0.019) -
0.28 (0.021) 0.24 (0.022) 0.23 (0.0281 0.19(0.021)
-
-
~~
-
-
376 All correlations: P = 0.0001. ASE in parentheses LTP = log total panic attacks.
Table 3. Item-item and item-total correlations at baseline (Pearson r ) PASS 1 PASS2 PASS3 PASS4 PASS5 PASS6 PASS7 PASS8 PASS9
PASS 1 1 PASS 2 0.74 1 PASS 3 -0.03 -0.1 1 1 PASS 4 -0.10 -0.03 0.57 1 PASS 5 0.42 0.35 -0.08 -0.07 1 PASS 6 0.31 0.38 -0.06 0.03 0.68 PASS 7 0.13 0.19 0.17 0.24 0.11 PASS8 0.15 0.25 0.14 0 . 2 9 0 . 1 0 PASS 9 0.30 0.30 0.02 0.09 0.26 Total 0.60 0.63 0.32 0.40 0.50
Age and sex 1 0.15 0.24 0.26 0.54
1 0.62 0.18 0.59
1 0.23 0.62
1 0.63
All correlations >0.1 or
