Convergence
of American and Scandinavian Functional Psychoses
Alv A. Dahl, C. Robert Cloninger, One hundred ninety-nine case summaries of a consecutive sample of functional psychoses, which had been classified by Odegard, were diagnosed independently using DSM-III-R criteria by four experienced psychiatrists. Odegard’s classification and DSM-III-R showed high concordance for schizophrenia and affective psy-
T
HE US/UK Diagnostic Project’ demonstrated considerable differences in the classification of functional psychoses across the Atlantic. American psychiatrists had a significantly broader concept of schizophrenia than the British, while the opposite was true for affective psychoses. Such conceptual differences between psychiatrists make communication and interpretation of scientific results problematic. Due to the reliance on operationalized criteria with higher interrater reliability of diagnoses, the American classification system DSMIII has received considerable international acclaim. The Tenth International Classification of Diseases (ICD-10) of the World Health Organization will be based on operational diagnostic criteria, and a convergence of the ICD and DSM systems is expected in the future. The international success of DSM-III and its successor DSM-III-R raises the question: What would the results of important psychiatric studies done in the past be in DSM-III-R terms? For example, Bergem et al.’ recently showed that Langfeldt’s schizophreniform cases mainly had affective disorders when reclassified in DSMIII-R. Norwegian psychiatry has made important contributions to the genetics, classification, and outcome of functional psychoses by studies of Langfeldt,’ Odegfrd,’ Astrup et a1.,4Retterstol,’ and Kringlen,’ among others. The studies by 0degfrd and Astrup were performed at Gaustad Hospital, where the diagnostic tradition was formed mainly by Bdegard, who was medical director from 1938 to 1973. Based on his diagnoses of functional psychoses, 0degard also formulated a multifactorial theory of inheritance in schizophrenia.’ (ddegard’s results have recently been taken as support for a continuity concept of psychosis by Crow.‘,” Since we are ComprehensivePsychiatry,
Vol.33,No.
Diagnoses
of
Samuel B. Guze, and Nils Retterstol chases. Odegard’s concept of reactive psychoses had high concordance with atypical psychoses in DSMIll-R. These findings imply that the results of genetic and follow-up studies from Scandinavia might be relevant for these diagnostic categories in DSM-III-R. Copyright 0 1992 by W. 6. Saunders Company
skeptical of Crow’s interpretation, we wanted to investigate 0degfrd’s findings further. As a starting point, we first asked: What is the correspondence between 0degard’s diagnoses of functional psychoses and DSM-III-R diagnoses? This report answers that question. The answer also has broader implications, since OdegPrd was a typical representative of Scandinavian psychiatric research of his time. Therefore, our findings might, with caution, be relevant for other important Scandinavian studies performed before the introduction of diagnostic systems based on operationalized criteria. METHOD The Gaustad Hospital family study of functional psychoses”.” was based on 201 consecutive first-admission patients with such diagnoses. All these cases were diagnosed by 0degird. Since the patients were admitted between 1930 to 1932 and 1948 to 19.50,their long-term outcome was known. Two cases were omitted, as their psychoses were probably due to organic conditions. An American psychologist, who spoke and read Norwegian, worked as a research assistant and made case summaries in English of the 199 records. The case summaries were one and one-half to three pages long, and the descriptions of psychopathology in them were mainly of high quality. The summaries were then distributed to the four authors, all experienced clinicians and researchers. They independently diagnosed the cases according to DSM-III-R, without knowledge of 0degPrd’s diagnoses. Later, a consensus conference was held, where the raters’ diagnoses were presented. In case of discordance, a consensus diagnosis
From the Department of Psychiatry and Gaustad Hospital, Faculty of Medicine, Oslo University, Oslo, Notway; and the Department of Psychiatry, Washington Univ~ersitySchool of Medicine, St Louis, MO. Supponed by a grant from the Schottish Rite Foundation for the study of schizophrenia. Address reprint requests to Alv A. Dahl, M.D., Depattment of Pqchiatty Uni~~ersity of Oslo, PO Box 85, finderen. 0319 Oslo 3, Norway. Copyright 0 1992 by K B. Saunders Company OOIO-44OXl9213301-0016$03.0010
l(January/February),1992:pp13-16
13
DAHL ET AL
14
Table 1. DSM-III-R Diagnoses of 199 Cases of Functional Psychoses by Members of the St Louis/Oslo
Rater
Schizophrenia
Affective
Delusional
Team
Atypical
Other
Cloninger
119
57
5
15
3
Dahl
140
46
3
7
3
Guze
113
32
4
47
3
Retterstptl
131
32
6
27
3
Consensus
127
44
4
21
3
was reached after discussion. 0degard had only three main diagnoses in the material: schizophrenia, manic-depressive psychoses, and reactive psychoses. The group of affective psychoses in the study consisted for 0deggrd’s part of manic-depressive and reactive depressive psychoses, and for the DSM-III-R part of bipolar and major depressive disorders. Independently, the 199 cases were classified as to the type of psychoses in first-degree relatives: schizophrenia, affective psychoses, mixed or other psychoses, or no psychotic disorder. The probands’ global long-term outcome were also rated independently as good, medium, or poor. The interrater reliability and the agreement between 0degfird’s diagnoses and consensus diagnoses of the team, were calculated by kappa statistics based on three-digit diagnoses. Differences in diagnostic rates between the evaluators were calculated by the chi-square statistic with Yates’ correction when necessary. RESULTS
The raters diagnosed a variable number of cases with the various functional psychoses. Dahl found significantly more cases of schizophrenia than Cloninger (P < .OS) and Guze (P < .Ol). On the other hand, Guze diagnosed significantly more cases with atypical psychosis than any of the other raters (P < .Ol). Cloninger had a significantly higher number of cases with affective psychoses than Guze and Retterstol (P < .OOl) (Table 1). The raters seemed to have significant different predilections for various functional psychoses-Dahl for schizophrenia, Guze for atypical psychosis, and Cloninger for affective psychoses, while Retterstal was more neutral. However, these personal idiosyn-
crasies had only moderate influence on the interrater reliability. Measured by the kappa statistic, interrater reliability between pairs of raters ranged from -81 to .86 for schizophrenia, .83 to .95 for affective psychoses, .72 to .89 for atypical psychoses, and .69 to .82 for all diagnoses (Table 2). OdegPrd diagnosed 123 cases with schizophrenia, 41 with affective psychoses, and 35 cases with reactive psychoses. In contrast, the consensus diagnoses of the St Louis/Oslo team were 127 cases with schizophrenia, 44 with affective psychoses, 4 with delusional disorders, 21 with atypical psychosis, and three cases with nonpsychotic disorders in DSM-III-R (Table 3). The diagnostic agreements between 0degArd’s diagnoses and the DSM-III-R team diagnoses were K = .87 for schizophrenia, .91 for affective psychoses, .81 for reactive/atypical psychoses, and .78 for all diagnoses. The lowest diagnostic agreement was found for 0degard’s 35 cases with reactive psychoses, which consisted of 13 cases of paranoid, 17 of hysterical, and five of other subtypes (Table 4). These cases of reactive psychoses spread over five axis I and axis II disorder groups in DSMIII-R, with a majority of the schizophrenia (12 cases) and atypical psychosis (12 cases) groups. When (ddegard’s affective psychoses cases were broken down into manic-depressive and reactive depressive psychoses, all nine cases with bipolar disorders were in the first group and all
Table 2. lnterater Reliability Between Members of the St Louis/Oslo Team of DSM-III-R Diagnoses of Functional Psychoses (kappa) Pairs of Raters
Schizophrenia
Affective
Atypical
Total
Cloninger/Dahl
.84
.88
.89
.79
CloningeriGuze
.81
.a4
.72
.69
Cloninger/Retterstel
.82
.83
.78
.72
Dahl/Guze
.83
.90
.78
.75
DahVRetterst0I
.86
.92
.88
.81
Guze/Retterst0I
.&a
.95
.85
.82
CONVERGENCE OF AMERICAN
AND SCANDINAVIAN
15
DIAGNOSES
Table 3. Distribution of 0degPrd’s Versus St Louis/Oslo
Team’s Diagnoses
Odegard’s Diagnoses Affective
St. Louis/Oslo Team’s Diagnoses
Schizophrenia
Schizophrenia Affective
disorders
Delusional Atypical
disorders
psychoses
Other disorders Sum
Psychoses
Reactive Psychoses
Sum
113
2
12
127
4
35
5
44
1
0
3
4
5
4
12
21
0
0
3
3
123
41
35
199
Table 4. Subclassification of 0degPrd’s Reactive Psychoses 0degard’s Reactive Psychoses
St Louis/Oslo Team’s Diagnoses
Paranoid
Hysterical
Other
Sum
Schizophrenia,
paranoid
7
0
0
Schizophrenia,
other
0
4
1
5
1
1
1
3
Bipolar disorder
0
2
0
2
Delusional
2
1
0
3
3
6
3
12
0
1
0
1
0
2
0
2
13
17
5
35
Major depressive
Atypical
disorder
disorder
psychoses
Obsessive-compulsive Personality
disorder
disorder
Sum
four cases with atypical psychoses in the latter (Table 5). The cases with major depressive disorder were equally distributed between the groups. We found minimal differences between (ddegird and DSM-III-R as to classification of psychosis in the families and classification of outcome for schizophrenia, affective psychoses, or reactive/atypical psychoses (Table 6). DISCUSSION
The case summary method was chosen for this study, since the records were in Norwegian, With this method, all the raters are presented with the same diagnostic information; however, they might interpret it differently. Generally, the interrater agreements are consistently high
7
for schizophrenia (> .81) and for affective psychoses (> .83). The concordance for atypical psychosis is somewhat lower (> .69), which might be due to the residual category status without criteria for this diagnosis. Our interrater agreements between pairs of raters are considerably higher than that observed by Bergem et al.’ and in the Nordic study of reactive psychosis” using the same method. This might be caused by a higher quality of the description of the psychopathology of the case summaries or by a higher degree of experience with DSMIII-R of the raters in the present study. The high interrater reliability implies that few consensus diagnoses had to be based on discussions, and that the majority of these cases were diagnostically clear-cut according to DSM-
Table 5. Subclassification of 0degBrd’s Affective Psychoses 0degard’s Affective St Louis/Oslo Team’s
Manic-Depressive
Diagnoses
Schizophrenia Major depressive
Psychosis
1 disorder
12
Psychoses
Reactive-Depressive Psychosis
1
Sum
2
14
26
Bipolar disorder
9
0
9
Atypical
0
4
4
22
19
41
Sum
psychoses
16
DAHL ET AL
Table 6. Psychosis in First-Degree Relatives and Outcome in Schizophrenia, Affective Psychoses, Reactive, and Atypical Psychoses According to 0degBrd and St Louis/Oslo
Team (%I
Psychosis in Family Disorder
Rater
Sch
Aff
Schizophrenia
0deglrd
25
Schizophrenia
StL/Os
Affective
psychoses
Affective
psychoses
Outcome
Mix
Pw
NOW
7
4
11
53
2
11
a7
25
9
4
9
53
3
10
a7
0degkd
12
10
7
12
59
56
25
19
StL/Os
11
9
7
11
62
51
28
21
Good
Medium
POW
Reactive psychoses
0deglrd
11
11
3
14
60
37
37
26
Atypical
QL/Os
15
10
0
20
55
52
22
26
psychoses
Abbreviations:
StL/Os, St Louis/Oslo
and affective psychoses;
Psy, psychoses
diagnostic
team; Sch, schizophrenia;
Aff, affective
psychoses;
Mix, mixture
of schizophrenia
unspecified.
III-R. One could argue that the cases were selected, but that was not true, since they were consecutive first admissions with a diagnosis of functional psychosis. The consensus diagnoses had a high concordance with (ddegard’s diagnoses, particularly for schizophrenia (.87) and affective psychoses (.91). Half of 0degPrd’s reactive paranoid psychoses were classified as paranoid schizophrenia in DSM-III-R by us, while his reactive hysterical psychoses were more heterogeneous in DSM-III-R according to our judgements. However, the concordance between 0deglrd’s concept of reactive psychosis and DSM-III-R atypical psychosis was considerable (.81). This finding is in accordance with 0deglrd’s view of reactive psychoses as the “third” nonschizophrenic, nonaffective group of functional psychoses.” Our results show that the DSM-III-R concepts of schizophrenia, affective psychoses, and atypical psychoses are quite close to 0degard’s concepts of schizophrenia, affective psychoses, and reactive psychoses, respectively. This is also confirmed by the nonsignificant differences be-
tween the proportions of psychoses in the families and global outcomes in this sample when classified by 0deglrd or by DSM-III-R. Our results so far justify further analysis of the family data before we can take a definite stand on Crow’s interpretation. These results imply that the findings of the Norwegian follow-up and genetic studies of functional psychoses might be relevant for the corresponding diagnostic concepts of DSMIII-R. This study points to a convergence of the older Scandinavian diagnostic tradition of functional psychoses and the new American one created by DSM-III-R. If that is true, a field of interesting comparisons between samples can be made, particularly since many Scandinavian studies are different in culture, time, and treatment compared with modern ones. This will also knit studies together in a wider context, instead of being interpreted as isolated findings. ACKNOWLEDGMENT We want assistance.
to thank Jeanette
Hawkins, Ph.D., for her
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7. 0deglrd 0. The multifactorial theory of inheritance in predisposition to schizophrenia. In: Kaplan AR (ed): Genetic Factors in “Schizophrenia.” Springfield, IL: Thomas, 19721256. 8. Crow TJ. Psychosis as a continuum and the virogene concept. Br Med Bull 1987;43:754-767. 9. Crow TJ. The continuum of psychosis and its genetic origins. Br J Psychiatry 1990;156:788-797. 10. Hansen H, Dahl AA, Bertelsen A, et al. The Nordic concept of reactive psychosis-a multicenter diagnostic reliability study. J Nerv Ment Dis (submitted). 11. Dahl AA. Problems concerning the concept of reactive psychoses. Psychopathology 1987;20:79-86.