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Assessment of depression by questionnaire compared to DSM-III diagnosis
Journal o/ Affectke Elsevier
167
Disorder.~. 8 (1985) 167-l 70
JAD 0027X
Assessment
of Depression by Questionnaire DSM-III Diagnosis Vaughan
The Unicersity of Adelaide, Depurtment
Compared
to
Carr and Jay Smith
of Psychiutry. Royal Adelarde Hospltul. Adelude.
SA 5000 (Australia)
(Received 25 April. 1984) (Revised. received 15 August. 1984) (Accepted 20 August, 1984)
Summary The LPD, a self-report questionnaire which provides a quantitative and qualitative measure of depression, was examined in relation to a criterion-based system of diagnosis, the DSM-III. Results from 190 psychiatric inpatients suggest that the LPD distinguishes depressive from non-depressive syndromes in terms of severity of depression and that patients with melancholic major depression are more severely depressed than those with non-melancholic major depression. Furthermore, major depression with melancholia and major depression without melancholia, both conform to the LPD profile of endogenous depression whereas other depressive syndromes do not. A comparison of the two systems of categorizing depression also suggests that the LPD is a relatively sensitive predictor of the diagnosis of major depressive disorder.
Key words:
DSM-III diagnosis - Endogenous depression - Major depressive disorder _ Melancholia Levine-Pilowsky Depression (LPD) Questionnaire - Self-report questionnaire
Introduction Currently, criterion-based systems of diagnosis (e.g. DSM-III) or objective rating scales which either measure severity (e.g. Hamilton 1960) or classify (e.g. Carney et al. 1965) depression are the most widely employed methods of assessing depressive disorders in clinical psychiatric research. In contrast, self-report questionnaires are less often used and only one such instrument attempts to provide both a quantitative and qualitative index of depression. This is the Levine-Pilowsky Depression Questionnaire (Pilowsky et al. 1969), a 0165-0327/85/$03.30
0 1985 Elsevier Science Publishers
-
self-report instrument of 57 items requiring YES/ NO responses. Nineteen items yield a measure of the overall severity of depression and the pattern of the respondent’s symptomatology is classified in a clinically useful way. By means of a decision rule, the Levine-Pilowsky Depression Questionnaire (LPD) yields a set of probability statements upon which the subject’s pattern of answers to the questionnaire can be assigned to one of three groups (Pilowsky and Boulton 1970). These are non-endogenous depression (class l), endogenous depression (class 2) and not-depressed (class 3). The methodology and
B.V. (Biomedical
Division)
168
validation of the LPD have been previously rcported and will not be further discussed here (Pilowsky and Boulton 1970; Pilowsky and McGrath 1970; Pilowsky and Spalding 1972: Pilowsky 1979). The present study was undertaken to examine the extent to which the LPD category of endogenous depression was concordant with a DSM-III diagnosis of major depressive disorder.
tient ih a member of the category to which he/she has been allocated. Most of the items which comprise the class 1 vs class 2 score are those traditionally associated with the endogenous syndrome and include, for example. loss of appetite. terminal insomnia and diurnal mood variation.
Subjects
The DSM-III diagnoses were first collapsed to form three groups. namely. major depressive disorder, other depressive syndromes (dysthymic disorder and adjustment disorder with depressed mood) and non-depressive disorders. This method of classification was chosen because it seemed that the resultant groups of diagnoses corresponded most closely to the three categories yielded by the LPD. namely, endogenous depression, non-endogenous depression and not-depressed, respectively. Using these three groups based on DSM-III diagnoses. a one-way analysis of variance was undertaken with depression score as the dependent variable. This yielded a significant result as shown in Table 1. The major effect in this analysis appeared to result from the low depression score for non-depressive syndromes in comparison with the two groups of depressive syndromes. There was a significant difference (Student’s r-test) in depression score between the group of non-depressive syndromes and that composed of dysthymic and adjustment disorders (P < 0.01. one-tailed) but not between the latter and major depressive disorder. With the same three diagnostic groups a second one-way analysis of variance was undertaken using the class 1 vs class 2 score as the dependent variable. As shown in Table 1, a significant result was obtained where the main effect appeared to be due to the substantial negative class I vs class 2 score of the major depressive disorder group compared with the other two diagnostic groups. The class 1 vs class 2 score for major depressive disorder differed significantly from that of the dysthymic and adjustment disorder group (P < 0.001. one-tailed) whereas the latter did not differ significantly from the group of other non-depressive syndromes. When the major depressive disorder group was divided into those with and without melancholia, the melancholic subgroup had a higher depression
The 190 subjects for this study were drawn from a consecutive series of admissions to the inpatient psychiatric service of the Royal Adelaide Hospital. All patients with organic psychiatric syndromes were excluded. Subjects with a DSM-III diagnosis of bipolar disorder, depressed type. were also excluded as there were insufficient numbers to form a statistically useful group. There were 67 males and 123 females in the sample. The mean age for the entire sample was 43.X years (SD 17.54), and there was no significant age difference between the sexes. Method
Within 48 hours of admission, all subjects completed the LPD questionnaire. DSM-III diagnoses were made by consensus agreement between a consultant psychiatrist and a senior trainee in psychiatry on the basis of case records and clinical interviews. Three aspects of the LPD in relation to DSM-III diagnoses were explored in turn. These were the depression score. the class 1 (non-endogenous) vs class 2 (endogenous) score and the final categorization as endogenous depression. non-endogenous depression or not-depressed. The depression score which ranges from 0 to 19 is the measure of depression severity. The range of possible class 1 vs class 2 scores is -20 to +30 and this scale, in providing an estimate of “endogenicity”, is the measure whereby the decision to classify the patient’s responses as endogenous or non-endogenous depression is made. A negative score suggests the presence of endogenous depression whereas a positive score suggests that the endogenous syndrome is absent. The magnitude of the score provides an estimate of the probability that the pa-
Results
169 TABLE
1
ANOVA
FOR DIAGNOSTIC
GROUPS
AND LPD SCORES
Major depressive disorder
11.29
Mean of LPD depression scores
12.07 (k4.14)
Mean of LPD class 1 vs class 2 scores
-4.19
+0.80
( + 4.46)
( k 6.05)
( k 4.08)
the non-melancholic subgroup (P = Melancholic and non-melancholic subjects with major depressive disorder, however, did not differ in terms of the class 1 vs class 2 scores. Further analyses were performed in order to determine the effects of age and sex on the depression and 1 vs 2 scores. Since age is one of several variables which are used in determining the 1 vs 2 score, we expected a significant correlation between age and the 1 vs 2 score but not the depression score. These predictions were confirmed. The Pearson correlation coefficient for age and 1 vs 2 score was -0.30 (P = 0.001) and that for age and depression score was -0.05 (NS). To further explore the effects of age and sex, a two-way analysis of variance of the 1 vs 2 score was performed between sex and the three diagnostic groupings with age as a covariate. As expected. age was a significant covariate (F = 20.742; df= 1:189; P < score
than
0.001, two-tailed).
TABLE
Non-depressive syndromes
Dysthymic disorder + Adjustment disorder with depressed mood
x.95 ( k 4.46)
F=l1.034 d/= 2:187 P < 0.001
+ 1.08 ( + 6.52)
F=18.162 d/ = 2:187 P < 0.001
0.01) and there was an overall diagnostic group difference (F = 11.749; u”= 2:189; P < 0.01) but no sex difference. There was no significant two-way interaction between diagnostic group and sex when age was held constant. A further two-way analysis of variance using the depression score was then performed between sex and the three diagnostic groupings. This analysis revealed a significant diagnostic group effect (F = 9.532; df = 2:189; P -c 0.01) but no sex difference and no two-way interaction between diagnostic group and sex. Finally, the LPD categories were examined to determine how concordant they were with DSM-III diagnoses. For this purpose, we compared the three DSM-III diagnostic groups with the LPD categories in a x2 analysis (Table 2). The results of this analysis suggest that the LPD categories bear some relationship to the broad DSM-III diagnostic groups and that the LPD category of endogenous depression is significantly associated with the
2
x2 COMPARISON
OF LPD CATEGORIES
Endogenous depression
n=190 Major depressive disorder (with or without melancholia) Dysthymic + Adjustment
AND DIAGNOSTIC
GROUPS Non-endogenous depression
Not depressed
45
4
22
14
10
7
27
13
48
disorder disorder
Non-depressive
with depressed
syndromes
x2 = 28.408. 4 df. P < 0.001
mood
170
DSM-III diagnosis of major depressive disorder. These figures also indicate that the LPD has a diagnostic sensitivity (or true-positive rate) of 63%’ and a specificity (or true-negative rate) of 66% for the DSM-III diagnosis of major depressive disorder. Conclusions
In this clinically heterogeneous sample of patients, it can be concluded that the LPD depression score helps to distinguish depressive syndromes from the other diagnostic groups based on the DSM-III classification. Furthermore, the LPD depression score suggests that patients suffering from major depressive disorder with melancholia are more severely depressed than those with nonmelancholic major depressive disorder. Secondly, major depressive disorder is distinguishable from other depressive and non-depressive syndromes in terms of the LPD class 1 vs class 2 measure of melancholic and nonendogenicity whereas melancholic major depressive disorders do not differ on this measure. This suggests that, according to the LPD, melancholic and non-melancholic major depressive disorders appear to be variants of the endogenous syndrome differing only in overall severity of depression. Finally, as presently constructed, the LPD as a predictor of the DSM-III diagnosis of major depressive disorder, is an instrument of moderate sensitivity but relatively low specificity. It is possible that this specificity figure could be improved by means of a re-analysis of the patterns of response to the LPD. On the other hand, it is worth considering that the “endogenous syndrome” may
indeed occur in the course of a variety of psychiatric illnesses other than major depressive disorder. Acknowledgements
The authors gratefully acknowledge the assistance of Professor I. Pilowsky in the preparation of this paper. They also thank M. Katsikitis and P. Thomas of the University of Adelaide, Department of Psychiatry, for their help with the statistical analysis. Copies of the LPD may be obtained from Professor I. Pilowsky. The University of Adelaide, Department of Psychiatry, Adelaide. SA 5000, Australia. References Carney, M.W.P.. Roth, M. and Garsidr. R.F.. The diagnosis of depression and the prediction of ECT response, Brit. J. Psychlat.. 111 (1965) 659-674. Hami1ton.M.. A rating scale for depression. J. Neural. Neurosurg. Psychiat.. 23 (1960) 56-62. Pilowsky, 1.. Further validation of a questionnaire method for classifying depressive illness, J. Affect. Dis., 1 (1979) 179%1X5. Pllowsky, I. and Boulton, D.M., Development of a questionnaire-based decision rule for classifying depressed patients. Brit. J. Psychiat., 116 (1970) 647-650. Pilowsky. 1. and McGrath, M.D., The effect of ECT on responses to a depression questionnaire ~ Implications for taxonomy, Brit. J. Psychiat., 117 (1970) 6X5-688. Pilowsky. I. and Spalding. D.. A method for measuring depression ~ Validity studies on a depression questionnaire, Brit. J. Psychiat.. 121 (1972) 411-416. Pilowsky. I.. Levine, S. and Boulton. D.M.. The classification of depression by numerical taxonomy. Brit. J. Psychiat., 115 (1969) 937-945.
167
Disorder.~. 8 (1985) 167-l 70
JAD 0027X
Assessment
of Depression by Questionnaire DSM-III Diagnosis Vaughan
The Unicersity of Adelaide, Depurtment
Compared
to
Carr and Jay Smith
of Psychiutry. Royal Adelarde Hospltul. Adelude.
SA 5000 (Australia)
(Received 25 April. 1984) (Revised. received 15 August. 1984) (Accepted 20 August, 1984)
Summary The LPD, a self-report questionnaire which provides a quantitative and qualitative measure of depression, was examined in relation to a criterion-based system of diagnosis, the DSM-III. Results from 190 psychiatric inpatients suggest that the LPD distinguishes depressive from non-depressive syndromes in terms of severity of depression and that patients with melancholic major depression are more severely depressed than those with non-melancholic major depression. Furthermore, major depression with melancholia and major depression without melancholia, both conform to the LPD profile of endogenous depression whereas other depressive syndromes do not. A comparison of the two systems of categorizing depression also suggests that the LPD is a relatively sensitive predictor of the diagnosis of major depressive disorder.
Key words:
DSM-III diagnosis - Endogenous depression - Major depressive disorder _ Melancholia Levine-Pilowsky Depression (LPD) Questionnaire - Self-report questionnaire
Introduction Currently, criterion-based systems of diagnosis (e.g. DSM-III) or objective rating scales which either measure severity (e.g. Hamilton 1960) or classify (e.g. Carney et al. 1965) depression are the most widely employed methods of assessing depressive disorders in clinical psychiatric research. In contrast, self-report questionnaires are less often used and only one such instrument attempts to provide both a quantitative and qualitative index of depression. This is the Levine-Pilowsky Depression Questionnaire (Pilowsky et al. 1969), a 0165-0327/85/$03.30
0 1985 Elsevier Science Publishers
-
self-report instrument of 57 items requiring YES/ NO responses. Nineteen items yield a measure of the overall severity of depression and the pattern of the respondent’s symptomatology is classified in a clinically useful way. By means of a decision rule, the Levine-Pilowsky Depression Questionnaire (LPD) yields a set of probability statements upon which the subject’s pattern of answers to the questionnaire can be assigned to one of three groups (Pilowsky and Boulton 1970). These are non-endogenous depression (class l), endogenous depression (class 2) and not-depressed (class 3). The methodology and
B.V. (Biomedical
Division)
168
validation of the LPD have been previously rcported and will not be further discussed here (Pilowsky and Boulton 1970; Pilowsky and McGrath 1970; Pilowsky and Spalding 1972: Pilowsky 1979). The present study was undertaken to examine the extent to which the LPD category of endogenous depression was concordant with a DSM-III diagnosis of major depressive disorder.
tient ih a member of the category to which he/she has been allocated. Most of the items which comprise the class 1 vs class 2 score are those traditionally associated with the endogenous syndrome and include, for example. loss of appetite. terminal insomnia and diurnal mood variation.
Subjects
The DSM-III diagnoses were first collapsed to form three groups. namely. major depressive disorder, other depressive syndromes (dysthymic disorder and adjustment disorder with depressed mood) and non-depressive disorders. This method of classification was chosen because it seemed that the resultant groups of diagnoses corresponded most closely to the three categories yielded by the LPD. namely, endogenous depression, non-endogenous depression and not-depressed, respectively. Using these three groups based on DSM-III diagnoses. a one-way analysis of variance was undertaken with depression score as the dependent variable. This yielded a significant result as shown in Table 1. The major effect in this analysis appeared to result from the low depression score for non-depressive syndromes in comparison with the two groups of depressive syndromes. There was a significant difference (Student’s r-test) in depression score between the group of non-depressive syndromes and that composed of dysthymic and adjustment disorders (P < 0.01. one-tailed) but not between the latter and major depressive disorder. With the same three diagnostic groups a second one-way analysis of variance was undertaken using the class 1 vs class 2 score as the dependent variable. As shown in Table 1, a significant result was obtained where the main effect appeared to be due to the substantial negative class I vs class 2 score of the major depressive disorder group compared with the other two diagnostic groups. The class 1 vs class 2 score for major depressive disorder differed significantly from that of the dysthymic and adjustment disorder group (P < 0.001. one-tailed) whereas the latter did not differ significantly from the group of other non-depressive syndromes. When the major depressive disorder group was divided into those with and without melancholia, the melancholic subgroup had a higher depression
The 190 subjects for this study were drawn from a consecutive series of admissions to the inpatient psychiatric service of the Royal Adelaide Hospital. All patients with organic psychiatric syndromes were excluded. Subjects with a DSM-III diagnosis of bipolar disorder, depressed type. were also excluded as there were insufficient numbers to form a statistically useful group. There were 67 males and 123 females in the sample. The mean age for the entire sample was 43.X years (SD 17.54), and there was no significant age difference between the sexes. Method
Within 48 hours of admission, all subjects completed the LPD questionnaire. DSM-III diagnoses were made by consensus agreement between a consultant psychiatrist and a senior trainee in psychiatry on the basis of case records and clinical interviews. Three aspects of the LPD in relation to DSM-III diagnoses were explored in turn. These were the depression score. the class 1 (non-endogenous) vs class 2 (endogenous) score and the final categorization as endogenous depression. non-endogenous depression or not-depressed. The depression score which ranges from 0 to 19 is the measure of depression severity. The range of possible class 1 vs class 2 scores is -20 to +30 and this scale, in providing an estimate of “endogenicity”, is the measure whereby the decision to classify the patient’s responses as endogenous or non-endogenous depression is made. A negative score suggests the presence of endogenous depression whereas a positive score suggests that the endogenous syndrome is absent. The magnitude of the score provides an estimate of the probability that the pa-
Results
169 TABLE
1
ANOVA
FOR DIAGNOSTIC
GROUPS
AND LPD SCORES
Major depressive disorder
11.29
Mean of LPD depression scores
12.07 (k4.14)
Mean of LPD class 1 vs class 2 scores
-4.19
+0.80
( + 4.46)
( k 6.05)
( k 4.08)
the non-melancholic subgroup (P = Melancholic and non-melancholic subjects with major depressive disorder, however, did not differ in terms of the class 1 vs class 2 scores. Further analyses were performed in order to determine the effects of age and sex on the depression and 1 vs 2 scores. Since age is one of several variables which are used in determining the 1 vs 2 score, we expected a significant correlation between age and the 1 vs 2 score but not the depression score. These predictions were confirmed. The Pearson correlation coefficient for age and 1 vs 2 score was -0.30 (P = 0.001) and that for age and depression score was -0.05 (NS). To further explore the effects of age and sex, a two-way analysis of variance of the 1 vs 2 score was performed between sex and the three diagnostic groupings with age as a covariate. As expected. age was a significant covariate (F = 20.742; df= 1:189; P < score
than
0.001, two-tailed).
TABLE
Non-depressive syndromes
Dysthymic disorder + Adjustment disorder with depressed mood
x.95 ( k 4.46)
F=l1.034 d/= 2:187 P < 0.001
+ 1.08 ( + 6.52)
F=18.162 d/ = 2:187 P < 0.001
0.01) and there was an overall diagnostic group difference (F = 11.749; u”= 2:189; P < 0.01) but no sex difference. There was no significant two-way interaction between diagnostic group and sex when age was held constant. A further two-way analysis of variance using the depression score was then performed between sex and the three diagnostic groupings. This analysis revealed a significant diagnostic group effect (F = 9.532; df = 2:189; P -c 0.01) but no sex difference and no two-way interaction between diagnostic group and sex. Finally, the LPD categories were examined to determine how concordant they were with DSM-III diagnoses. For this purpose, we compared the three DSM-III diagnostic groups with the LPD categories in a x2 analysis (Table 2). The results of this analysis suggest that the LPD categories bear some relationship to the broad DSM-III diagnostic groups and that the LPD category of endogenous depression is significantly associated with the
2
x2 COMPARISON
OF LPD CATEGORIES
Endogenous depression
n=190 Major depressive disorder (with or without melancholia) Dysthymic + Adjustment
AND DIAGNOSTIC
GROUPS Non-endogenous depression
Not depressed
45
4
22
14
10
7
27
13
48
disorder disorder
Non-depressive
with depressed
syndromes
x2 = 28.408. 4 df. P < 0.001
mood
170
DSM-III diagnosis of major depressive disorder. These figures also indicate that the LPD has a diagnostic sensitivity (or true-positive rate) of 63%’ and a specificity (or true-negative rate) of 66% for the DSM-III diagnosis of major depressive disorder. Conclusions
In this clinically heterogeneous sample of patients, it can be concluded that the LPD depression score helps to distinguish depressive syndromes from the other diagnostic groups based on the DSM-III classification. Furthermore, the LPD depression score suggests that patients suffering from major depressive disorder with melancholia are more severely depressed than those with nonmelancholic major depressive disorder. Secondly, major depressive disorder is distinguishable from other depressive and non-depressive syndromes in terms of the LPD class 1 vs class 2 measure of melancholic and nonendogenicity whereas melancholic major depressive disorders do not differ on this measure. This suggests that, according to the LPD, melancholic and non-melancholic major depressive disorders appear to be variants of the endogenous syndrome differing only in overall severity of depression. Finally, as presently constructed, the LPD as a predictor of the DSM-III diagnosis of major depressive disorder, is an instrument of moderate sensitivity but relatively low specificity. It is possible that this specificity figure could be improved by means of a re-analysis of the patterns of response to the LPD. On the other hand, it is worth considering that the “endogenous syndrome” may
indeed occur in the course of a variety of psychiatric illnesses other than major depressive disorder. Acknowledgements
The authors gratefully acknowledge the assistance of Professor I. Pilowsky in the preparation of this paper. They also thank M. Katsikitis and P. Thomas of the University of Adelaide, Department of Psychiatry, for their help with the statistical analysis. Copies of the LPD may be obtained from Professor I. Pilowsky. The University of Adelaide, Department of Psychiatry, Adelaide. SA 5000, Australia. References Carney, M.W.P.. Roth, M. and Garsidr. R.F.. The diagnosis of depression and the prediction of ECT response, Brit. J. Psychlat.. 111 (1965) 659-674. Hami1ton.M.. A rating scale for depression. J. Neural. Neurosurg. Psychiat.. 23 (1960) 56-62. Pilowsky, 1.. Further validation of a questionnaire method for classifying depressive illness, J. Affect. Dis., 1 (1979) 179%1X5. Pllowsky, I. and Boulton, D.M., Development of a questionnaire-based decision rule for classifying depressed patients. Brit. J. Psychiat., 116 (1970) 647-650. Pilowsky. 1. and McGrath, M.D., The effect of ECT on responses to a depression questionnaire ~ Implications for taxonomy, Brit. J. Psychiat., 117 (1970) 6X5-688. Pilowsky. I. and Spalding. D.. A method for measuring depression ~ Validity studies on a depression questionnaire, Brit. J. Psychiat.. 121 (1972) 411-416. Pilowsky. I.. Levine, S. and Boulton. D.M.. The classification of depression by numerical taxonomy. Brit. J. Psychiat., 115 (1969) 937-945.