- Email: [email protected]
Racial differences in the diagnosis of psychosis
SCHIZOPHRENIA RESEARCH ELSEVIER
Schizophrenia Research 21 (1996) 117-124
Racial differences in the diagnosis of psychosis 1 Stephen M. Strakowski a,,, Michael Flaum b, Xavier Amador c, H. Stefan Bracha d, Anand K. Pandurangi e, Delbert Robinson f, Mauricio Tohen g a Psychotic Disorders Research Program, Department of Psychiatry, University of Cincinnati College of Medicine, 231 Bethesda Avenue, P.O. Box 670559, Cincinnati, OH 45267-0559, USA b Department of Psychiatry, University of Iowa, Iowa City, IA, USA c Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA d Department of Psychiatry, University of Hawaii, Burns School of Medicine, Honolulu, HL USA e Division of Inpatient Psychiatry, The Medical College of Virginia, Richmond, VA, USA f Long Island Jewish Medical Center-Hillside Hospital, New York, NY, USA g Bipolar and Psychotic Disorders Program, McLean Hospital, Belmont, MA, USA Received 18 December 1995; revision 4 April 1996; accepted 11 April 1996
Abstract
In clinical populations, it has been reported that African-American patients are more likely to receive a diagnosis of schizophrenia than similar Caucasian patients. Factors contributing to this racial discrepancy are poorly defined. The authors examined the hypothesis that racial differences in severity of first-rank symptoms of schizophrenia contribute to this diagnostic difference. Patients were recruited as part of the DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders, and evaluated using a structured rating instrument. Symptom and diagnostic comparisons were performed between black and white patients. Black patients were significantly more likely than white patients to be diagnosed with schizophrenia and less likely with psychotic depression. Racial differences in symptom profiles were observed with black patients demonstrating more severe psychotic symptoms, in general, and first-rank symptoms, specifically. There were no racial differences in rates of affective syndromes or severity of affective symptoms. Racial disparity in diagnosis of psychotic patients may be in part secondary to more severe first-rank symptoms in black patients, causing clinicians to stray from DSM-III-R criteria.
Keywords." Schizophrenia; Psychosis; Affective disorders; Race; First-rank symptoms
1. Introduction
In clinical settings, it has been observed that A f r i c a n - A m e r i c a n patients are disproportionately * Corresponding author. Tel.: (1-513) 558-1132; Fax: (1-513) 558-4805. ~Presented in part at the International Congress on Schizophrenia Research, April, 1995. 0920-9964/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved PII S0920-9964 (96) 00041-2
diagnosed with schizophrenia, c o m p a r e d to similar Caucasian patients, with a corresponding underdiagnosis o f affective syndromes (Neighbors et al., 1989; Mukherjee et al., 1981; Strakowski et al., 1993a, 1995, 1996; L a w s o n et al., 1994). These racial differences in diagnosis tend to decrease with strict adherence to diagnostic criteria, however (Keisling, 1981; Simon and Fleiss, 1973; Mukherjee et al., 1981). Moreover, in the recent
118
Stephen M. Strakowski et al./Sch&ophrenia Research 21 (1996) 117-124
Epidemiologic Catchment Area study there were no racial differences observed in the prevalences of major psychotic disorders after controlling for sociodemographic variables (Robins and Regier, 1991). By providing syndrome descriptions through the widespread use of DSM-III, and subsequently DSM-III-R and DSM-IV, it was hoped that these racial discrepancies in clinical diagnosis would diminish (Adebimpe, 1981; Neighbors et al., 1989). This provision does not appear to have been entirely effective, as recent studies continue to show excess rates of schizophrenic diagnoses in African-Americans (Strakowski et al., 1993b, 1995, 1996; Lawson et al., 1994). The reasons for this racial disparity in diagnosis are unclear, but have been hypothesized to be, at least in part, due to racial differences in the symptomatic presentations of affective and psychotic disorders (Adebimpe, 1981; Neighbors et al., 1989). Indeed, previous investigators have reported increased frequency and severity of hallucinations, paranoia and other psychotic symptoms in black as compared to white patients (Helzer, 1975; Adebimpe et al., 1981, 1982; Mukherjee et al., 1981; Lawson et al., 1984). These findings raise the possibility that psychotic symptoms that are associated with schizophrenia, such as the so-called first-rank symptoms of schizophrenia, may be more common in black than white patients and, therefore, could contribute to racial differences in diagnosis. Schneiderian first-rank symptoms have been widely used to make the diagnosis of schizophrenia and continue to be prominent in current classification systems (Schneider, 1959; Flaum and Andreasen, 1991). First-rank symptoms include auditory hallucinations of voice repeating or commenting on the patient's thoughts or behavior, two or more voices discussing the patient in the third person, and delusions of thought insertion or withdrawal, thought broadcasting, the sensation of being controlled by an external force and delusional perceptions. Several studies have seriously questioned the specificity of these symptoms for schizophrenia (Carpenter et al., 1973; Carpenter and Strauss, 1974; Pope and Lipinski, 1978; Andreasen and Flaum, 1991), but they continue to be used clinically for diagnosis. Thus, if African-American
patients with psychosis express first-rank symptoms more commonly or more severely than Caucasian patients, this might contribute to the increased rate of schizophrenia diagnosed in black patient samples. There have been few studies that have specifically examined racial differences in first-rank symptoms. The DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders was a multi-site study designed to test the reliability and concordance of several diagnostic criteria sets for the nonaffective psychotic disorders to use in DSM-IV (Flaum et al., 1996). In this Field Trial, patients with psychosis were evaluated using a semi-structured rating instrument designed to assess psychotic and affective symptoms, and diagnoses were made from those ratings with the various diagnostic criteria sets. This Field Trial dataset provides a unique opportunity to examine racial differences in the presentation of psychosis that may contribute to the higher rates of schizophrenia diagnosed in black patients in clinical samples by providing a large number of carefully evaluated patients. With these considerations in mind, we analyzed this dataset to determine whether racial differences in ratings of first-rank symptoms contribute to differences between black and white patients in rates of schizophrenia. Specifically, we tested the following hypotheses: (1) black patients in the Field Trial would have higher rates of schizophrenia diagnoses than white patients; and (2) black patients would receive higher ratings on first-rank symptoms.
2. Methods
2.1. Subjects Patients were recruited for the DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders as described elsewhere (Flaum et al., 1996). Briefly, patients were included if they demonstrated at least a mild degree of psychosis, and all subjects provided written informed consent in order to participate. Patients were excluded by a history of severe drug use that clouded the current diagnostic picture, if psychotic symptoms
Stephen M. Strakowski et al./Schizophren& Research 21 (1996) 117-124
appeared to be entirely secondary to a non-psychiatric medical cause or substance abuse, by a history of mental retardation, or if they could not be psychiatrically assessed. It was specified that there was to be no relationship between the probability of recruitment and the patterns of psychopathology, except that cases meeting criteria for a full affective syndrome were to be accepted at a lower rate (approximately 1:2). Racial comparisons were made only between patients designated as black or white, as the numbers of subjects with other racial designations were too small for meaningful analysis. (We chose to use the terms 'black' and 'white' rather than 'African-American' and 'Caucasian', as the former are how the races were designated on the Field Trial form.) The Mexican and the Australian sites were excluded from this analysis because of the racial homogeneity of those samples. 2.2. Raters
Forty raters participated in this study across the seven US sites. Twenty-seven were male and 13 were female. Thirty-four (85%) of the raters were white, non-Hispanic, two (5%) were Hispanic, two were of Middle-Eastern descent (5%; India, Pakistan) and the remaining two (5%) were Asian. Twenty-five raters were psychiatrists (13 postresidency, 12 residents or fellows), four were PhD psychologists and the remaining 11 were master and bachelor degree research assistants. The raters had a mean of 6 (SD 5) years working regularly with patients with psychotic disorders, and over 70% had prior experience using structured and semi-structured psychiatric interviews. 2.3. Clinical assessment
Using the semi-structured interview developed for the Field Trial, patients were evaluated for a wide range of psychiatric symptoms and behaviors. Current positive psychotic symptoms were rated on a 6-point ordinal scale (0 = none to 5 = severe) and included: delusions classified as persecutory, jealous, grandiose, somatic, referential, thought insertion, thought withdrawal, thought broadcasting, being controlled, perceptual, and other;
119
hallucinations classified as auditory, voices commenting, voices conversing, voices referred from body, thought echo, visual and other; formal thought disorder classified as derailment, tangentiality, incoherence, illogicality, neologisms, circumstantiality and poverty of content; and disorganized behavior including inappropriate sexual/social behavior, unusual clothing/ appearance, aggression/agitation, stereotypy and inappropriate affect. Negative symptoms (including affective flattening, alogia, avolition/ apathy and asociality) and catatonia were rated on the same ordinal scale. Current affective symptoms, taken from the DSM-III-R criteria for mania and depression, were rated dichotomously as present or absent. Affective syndromes (depression and mania) were also identified as present or absent according to whether patients met the respective syndrome criteria as defined in DSM-III-R. Current psychoactive substance use was rated on an ordinal scale as follows: 0--no use; 1 = experimental or occasional use; 2=maladaptive use; and 3 = abuse or dependence. For this current analysis, alcohol or drug abuse was rated as present if the alcohol or drug use score was greater than one, otherwise it was considered absent. A detailed analysis of substance abuse in this sample has been published previously (Strakowski et al., 1994). Following the completion of symptom ratings, raters were then instructed to apply the results of this evaluation to diagnose subjects with various diagnostic criteria sets (e.g., DSM-III, ICD-10) (Flaum et al., 1996). Most patients were evaluated by two raters to evaluate diagnostic reliability. Except for analyses of reliability, all information for each patient used for this analysis was that recorded by the primary rater. A more detailed analysis of diagnostic reliability has been published elsewhere (Flaum et al., 1996). 2.4. Statistical analysis
All analyses were performed on the Statistical Analysis System for the Personal Computer (SAS Institute, Cary, NC 1991). The hypothesized associations between race and diagnosis were analyzed using logistic regression adjusting for age, sex,
120
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
education, occupational status and site. Adjusted Odds Ratios (ORa) and 95% Confidence Interval (95% C1) were calculated from this analysis. To determine whether race was associated with reliability of the principal psychotic disorder diagnosis, kappa statistics (Cohen, 1968) were calculated for agreement of diagnoses for both the white and black patient subsets. Racial differences in symptoms were analyzed using a multivariate analysis of covariance (MANCOVA) adjusting for diagnosis, age, sex, education, alcohol and drug abuse. These covariates were chosen as they may confound observed racial differences in psychopathology (Neighbors et al., 1989). The MANCOVA permits determination of significant group differences in symptom profiles, but does not identify specific symptom differences. Thus, effect sizes for individual symptoms were calculated to determine which specific symptoms contributed to racial differences in symptom profiles. Effect size, d~, expresses the magnitude of the difference between group mean scores in terms of standard deviation units (Cohen, 1977). Specifically, ds =1~'1-X21/SD, where -~1 = mean of group one, -~2 = m e a n of group 2 and SD = standard deviation of the overall sample. In order to estimate effect sizes for individual variables adjusted for covariates, an adjusted leastsquares mean score for each racial subgroup and the root mean square error of the symptom were entered into the above equation. Effect sizes were calculated, rather than univariate multiple comparisons, for several reasons. First, post-hoc significance tests are binary decisions based on statistical criteria rather than the potential clinical importance. In contrast, effect size provides a direct estimate of the magnitude of the differences between two groups. Second, significance tests are dependent on sample size, so that even small clinical effects can be deemed 'significant' with a large enough patient sample. Effect size is independent of sample size, and therefore provides a better estimate of the magnitude of group differences. Third, post-hoc significance tests do not permit determination of the relative effects of different symptoms on the overall symptom difference. These tests only determine whether a given symptom is or is not significantly different between the
two groups (i.e., p < 0.05). Effects sizes, in contrast, permit determination of which symptoms most contribute to symptom profile differences. Finally, effect size calculations are not subject to Type I statistical errors, which is a limitation of even the best post-hoc test. Thus, for this particular analysis, in which we wished to determine whether overall symptom differences were present between racial groups, and then identify which symptoms most contributed to that difference, specifically whether first-rank symptoms contributed to the difference, the use of a MANCOVA followed by the calculation of effect sizes was preferred (Cohen, 1977). To interpret effect sizes, Cohen (1977) refers to a ds=0.2 as a small-effect size, a ds=0.5 as a medium-effect size and d~=0.8 as a large-effect size. In general, significant results in the behavioral sciences tend to exhibit small to moderate effect sizes.
3. Results
3.1. Demographics The 330 subjects had an average age of 34 years ( S D = 1 2 years) and were 62% male (n=205). Twenty-six percent of the sample was black (n = 86) and the remaining patients were white (n= 244). Patients had a mean educational level of 13 years ( S D = 3 ) , 68% were never married (n=225) and 49% were unemployed (n = 163). Patients had an average age of symptom onset of 24 years (SD = 10 years) and had six hospitalizations (SD = 7). Black patients demonstrated significantly lower levels of education (12.1 (SD=2.7) years versus 13.1 (SD=2.5) years; t=2.9, df=327, p=0.004). There were no other differences between black and white patients on any of these demographic variables. Black patients were unevenly distributed across sites (X2=36.8, df=6, p<0.0001) as follows: University of Iowa (8%), McLean Hospital (11%), Yale University (13%), Long-Island Jewish/ Hillside Hospital (35%), Columbia University (37%), Medical College of Virginia (37%) and the University of Arkansas (46%).
Stephen M. Strakowski et al./Schizophrenia Research21 (1996)117-124 3.2. Diagnosis The D S M - I I I - R diagnostic distribution is listed by race in Table 1. When adjusted for demographic variables, black patients were more likely to be diagnosed with schizophrenia ( O R a = l . 4 , 95% C I = 1.0-1.8; p = 0 . 0 3 ) and less likely to be diagnosed with psychotic depression ( O R a = 2 . 8 , 95% CI = 1.0-7.8; p =0.04). Indeed, only a single black patient received a diagnosis of psychotic depression, even though the rate of current depressive syndromes was nearly equal in both races (24% of black versus 29% of white patients; X2=0.6, d f = 1, p > 0.4). There were also no racial differences in rates o f current manic syndromes (17% black versus 19% white patients; Z2=0.08, d f = l , p > 0 . 7 ) . There were no differences in rater agreement of the D S M - I I I - R psychotic disorder diagnosis between white and black patients ( k a p p a = 0 . 6 8 versus 0.67, respectively). 3.3. Symptoms Significant racial differences were observed in s y m p t o m profiles ( M A N C O V A F = 1.7, d f = 5 9 , 262, p = 0.003; two subjects were excluded due to missing data). The main contributors to this difference were the psychotic symptoms, as no
121
negative or affective s y m p t o m exhibited an effect size (ds) greater than 0.3, and few o f these symptoms even exhibited a d s > 0.1. The effect sizes for first-rank symptoms are listed in Table 2. Hallucinations of voices commenting on the patient's behavior demonstrated the most robust effect size of any variable (ds = 0.57). Other effect sizes greater than 0.3 were observed for the first-rank symptoms of delusions o f thought withdrawal (ds=0.44), thought insertion (ds=0.32) and being controlled (d~=0.32). Other psychotic symptoms with ds > 0.3 included any auditory hallucination (4.0 ( S D = I . 0 ) vs. 3.2 ( S D = I . 5 ) ; d~ =0.48), any visual hallucination (2.0 (SD = 1.8) vs. 1.3 ( S D = 1.7); d , = 0 . 3 9 ) , grandiose delusions (2.1 ( S D = 2 . 0 ) vs. 1.5 ( S D = 1.8); d~ =0.35), incoherence (1.6 ( S D = 2 . 0 ) vs. 0.5 ( S D = I . 2 ) ; d~=0.38) and aggressive behavior (2.9 ( S D = 1.6) vs. 2.3 ( S D = 1.5); d~ =0.30). In all cases, the mean symptom scores for black patients were greater than those for white patients. Thus, the significant racial difference in s y m p t o m profiles resulted from small- and medium-effects from a number of psychotic symptoms, particularly first-rank symptoms, rather than large-effects from one or a few symptoms.
4. Discussion Table 1 Diagnostic distribution by race of patients from the DSM-IV Field Trial for schizophrenia and other psychotic disorders Diagnosis
Schizophrenia Bipolar disorder Schizoaffective disorder Schizophreniform disorder Major depression Delusional disorder Psychosis NOS Other
Black (n = 86) (%)
White (n = 244) (%)
Total (n = 330) (%)
52 (60)a 8 (9) 10 (12) 8 (9) 1 (1) b 2 (2) 3 (4) 2 (2)
117 (48) 30 (12) 26 (11) 16 (7) 20 (8) 13 (5) 12 (5) 10 (4)
169 (51 38 912) 36 (11) 24 (7) 21 (6) 15 (5) 15 (5) 12 (3)
NOS, not-otherwise-specified. aSignificant difference versus white; ORa=l.4, 95% CI= 1.0-1.8; p=0.03. bSignificant difference versus white; ORa=2.8, 95% CI= 1.0-7.8; p =0.04.
In this sample from the D S M - I V Field Trial for Schizophrenia and Other Psychotic Disorders, black patients were more likely than white patients to receive a D S M - I I I - R diagnosis of schizophrenia, Table 2 First-rank symptoms by race of patients from the DSM-IV Field Trial for schizophrenia and other psychotic disorders Symptom
Black White (n =86) (n =244) mean (SD) mean (SD)
Thought insertion 1.7 (1.8) Thought withdrawal 1.4 (1.8) Thought broadcasting 1.5 (1.9) Being controlled 1.9 (1.8) Delusional perception 0.9 (1.3) Voices commenting 2.7 (1.9) Voice conversing 1.9 (2.0)
1.0 (1.6) 0.7 (1.3) 1.0 (1.6) 1.2 (1.7) 0.8 (1.3) 1.5 (1.8) 1.5 (1.8)
Effect size, d, 0.32 0.44 0.28 0.32 0.14 0.57 0.25
122
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
and less likely to be diagnosed with psychotic depression. This racial difference in diagnosis may reflect a tendency by raters to see black patients as sicker, and conversely white patients as less ill, thereby leading to the observed racial differences in diagnostic assignment for both groups. Alternatively, the more severe first-rank symptoms in black patients may have influenced raters away from DSM-III-R criteria to diagnose schizophrenia, even with the criteria immediately available, and even though the rates of affective syndromes were similar between the racial groups. Indeed, there were significant racial differences in symptom profiles, with more severe psychotic symptoms in general, and first-rank symptoms specifically, in black patients. Whether these differences resulted from bias in the rating of symptoms (since the persons performing the ratings and making the diagnoses were the same), or reflect real racial differences in symptomatic presentation of psychosis cannot be determined in this study. Nonetheless, the prominent use of firstrank symptoms as diagnostic criteria may lead to racially disproportionate rates of diagnosing schizophrenia, suggesting that further study is needed to clarify racial and cultural differences in the expression of psychosis. As noted, the rate of DSM-III-R depressive and manic syndromes was not different between racial groups, even though black patients were much less likely to be given an affective disorder diagnosis, particularly of psychotic depression. Indeed, although 24% of the black patients had a current depressive syndrome identified, only a single patient (1%) was diagnosed with psychotic depression (compared with 29 and 8%, respectively, in white patients). The diagnoses of psychotic depression, schizoaffective disorder (depressed type) and schizophrenia with secondary depression lack clear phenomenological boundaries, which makes differentiating among these conditions quite difficult, even when using operationalized criteria sets (Siris et al., 1978). Thus, if the reliability and validity of distinguishing among these similar conditions is limited in general, then diagnoses of these patients may have been more susceptible to the influence of (nondiagnostic) symptom differences in this study specifically.
Other factors contributing to racial bias in diagnosis must also be considered. The cultural gap between the primarily white raters assessing black patients in this sample may have resulted in assigning pathology where it did not belong; e.g., misinterpreting culturally based jargon as thought disorder. Without direct measures of cultural misperception, however, this study could not directly assess these issues. It is also possible that the schizophrenia diagnosis was used as a pejorative label for black patients reflecting an underlying prejudice among the raters. Given the large number of clinical evaluators and the multi-site design, it seems unlikely that systematic prejudice alone explains the observed racial differences. Several limitations to this analysis must be considered when interpreting results. First, the DSM-IV Field Trial was primarily designed to evaluate the reliability and concordance of various diagnostic criteria sets for nonaffective psychotic disorders. Thus, as with any secondary analysis, conclusions are limited for those hypotheses that were not primary and, therefore, the results of this analysis should be viewed as preliminary. Specific information that might have clarified further those factors that influence diagnosis in different racial groups was not obtained, so could not be examined (e.g., racial preconceptions of raters). On the other hand, post-hoc analyses provide some protection against rater bias toward the tested hypotheses. A second limitation is the lack of generalizability of this sample to other samples of psychotic disorders. By identifying primarily nonaffective psychosis, the relative prevalence of affective psychoses was lower than would be expected in an epidemiological sample, which may have contributed to racial differences that would not be present with more general recruitment. Furthermore, the exclusion of significant substance abusers limits comparisons to other patient samples where substance use rates are higher (Regier et al., 1990; Strakowski et al., 1993a), and since substance abuse rates differ among racial groups in the US (Robins and Regier, 1991), this could have led to a racial sampling bias. Finally, most of the patients in this sample were hospitalized (Flaum et al., 1996), so racial differences in diagnosis may have reflected racial differences in factors leading to hospitalization.
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
These limitations are s o m e w h a t compensated for by the large n u m b e r o f patients and the multi-site design which strengthens the validity o f the findings. Despite these limitations, this study suggests that the disproportionate rate o f diagnosis o f schizophrenia in black patients m a y be, in part, due to m o r e severe first-rank s y m p t o m s o f schizophrenia in that subgroup, causing clinicians to stray f r o m diagnostic criteria. Thus, in multiculrural patient samples, first-rank s y m p t o m s o f schizophrenia m a y be m o r e culturally based than diagnostically specific. F u r t h e r research is clearly warranted.
Acknowledgment The D S M - I V Field Trial W o r k Group-Site C o o r d i n a t o r s were: Xavier A m a d o r , P h D and Jack G o r m a n , M D (Columbia University, N e w York, N Y ) ; H. Stefan Bracha, M D (University o f A r k a n s a s for Medical Sciences, Little R o c k , A R ) ; William Edell, P h D and T o m M c G l a s h a n , M D (Yale Psychiatric Institute, N e w Haven, C N ) ; A n a n d Pandurangi, M D and K e n n e t h Kendler, M D (Medical College o f Virginia, R i c h m o n d , VA); Delbert R o b i n s o n , MD and Jeffrey Lieberman, M D (LIJ-Hillside Medical Center, N e w York, N Y ) ; A l f o n s o Ontiveros, M D , MSc (Autonomous University of Nuevo Leon, Mexico); Mauricio Tohen ( M c L e a n Hospital, Belmont, M A ) ; Michael Flaum, M D and N a n c y C. Andreasen, M D , P h D (University o f Iowa, I o w a City, IA). The authors also t h a n k Stephan Arndt, P h D for his statistical assistance and William B. Lawson, M D for his c o m m e n t s on this manuscript. This research was supported in part by: N I M H G r a n t MH47200, M H C R C G r a n t MH43271, Scottish Rite Schizophrenia Research P r o g r a m N.M.J. G r a n t ( S M S ) and a grant f r o m the Ohio D e p a r t m e n t o f Mental Health (SMS).
References Adebimpe, V.R. (1981) Overview: white norms and psychiatric diagnosis of black patients. Am. J. Psychiatry 138, 279-285.
123
Adebimpe, V.R., Klein, H.E. and Fried, J. (1981) Hallucinations and delusions in black psychiatric patients, J. Natl. Med. Ass. 73, 517-520. Adebimpe, V.R., Chu, C.C., Klein, H.E. and Lange, M.H, (1982) Racial and geographic differences in the psychopathology of schizophrenia. Am. J. Psychiatry 139, 888-891. Andreasen, N.C. and Flaum, M. (1991) Schizophrenia: The characteristic symptoms. Schizophr. Bull. 17, 27-49. Carpenter, W.T., Strauss, J.S. and Muleh, S. (1973) Are there pathognomonic symptoms in schizophrenia. Arch. Gen. Psychiatry 28, 847-852. Carpenter, W.T. and Strauss, J.S. (1974) Cross-cultural evaluation of Schneider's first-rank symptoms of schizophrenia: A report from the International Pilot Study of Schizophrenia. Am. J. Psychiatry 131,682-687. Cohen, J. (1968) Weighted kappa: nominal scale agreement with provision for scaled disagreement or partial credit. Psychol. Bull. 70, 213-220. Cohen, J. (1977) Statistical power analysis for the behavioral sciences. New York: Academic Press. Flaum, M. and Andreasen, N.C. (1991)Diagnostic criteria for schizophrenia and related disorders: Options for DSM-IV. Schizophr. Bull. 17, 133-156. Flaum, M., Amador, X., Gorman, J., Bracha, H.S., Edell, W., McGlashan, T., Pandurangi, A., Kendler, K., Robinson, D., Lieberman, J., Ontiveros, A., Tohen, M., McGorry, P., Tyrrell, G., Arndt, S. and Andreasen, N.C. (1996) The DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders. Am. J. Psychiatry, in press. Helzer, J.D. (1975) Bipolar affective disorder in black and white men: A comparison of symptoms and familial illness. Arch. Gen. Psychiatry 32, 1140-1143. Keisling, R. ( 1981) Underdiagnosis of manic-depressive illness in a hospital unit. Am. J. Psychiatry 138, 672-673. Lawson, W.B., Yesavage, J.A. and Werner, P.D. (1984) Race, violence, and psychopathology. J. Clin. Psychiatry 45, 294-297. Lawson, W.B., Hepler, N., Holiday, J. and Cuffel, B. (1994) Race as a factor in inpatient and outpatient admissions and diagnosis. Hosp. Commun. Psychiatry 45, 72-74. Mukherjee, S., Shukla, S., Woodle, J., Rosen, A.M. and Olarte, S. ( 1981) Misdiagnosis of schizophrenia in bipolar patients: a multiethnic comparison. Am. J. Psychiatry 138, 279-285. Neighbors, H.W., Jackson, J.S., Campbell, L. and Williams, D. (1989) The influence of racial factors on psychiatric diagnosis: a review and suggestions for research. Commun. Ment. Health J. 25, 301-311. Pope, H.G., Jr. and Lipinski, J.F. (1978) Diagnosis in schizophrenia and manic-depressive illness: A reassessment of the specificity of 'schizophrenic' symptoms in the light of current research. Arch. Gen. Psychiatry 35, 811-828. Regier, D.A., Farmer, M.E., Rae, D.S., Locke, B.Z., Keith, S.J., Judd, LL. and Goodwin, F.K. (1990) Comorbidity of mental disorders with alcohol and other drug abuse: Results from the Epidemiologic Catchment Area (ECA) Study. J. Am. Med. Ass. 264, 2511-2518. Robins, L.N. and Regier, D. (Eds.) (1991) Psychiatric
124
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
Disorders in America: the Epidemiologic Catchment Area Study. The Free Press, New York, NY. Schneider, K. (1959) Clinical Psychopathology. (Hamilton, M.W., translator). Grune and Stratton, New York, NY. Simon, R. and Fleiss, J. (1973) Depression and schizophrenia in hospitalized patients. Arch. Gen. Psychiatry 14, 475-481. Sifts, S.G., van Kammen, D.P. and Docherty, J.P. (1978) Use of antidepressant drugs in schizophrenia. Arch. Gen. Psychiatry 35, 1368-1377. Strakowski, S.M., Shelton, R.C. and Kolbrener, M.L. (1993a) The effects of race and comorbidity on clinical diagnosis in patients with psychosis. J. Clin. Psychiatry 54, 96-102. Strakowski, S.M., Tohen, M., Stoll, A.L., Faedda, G.L., Mayer, P.V., Kolbrener, M.L. and Goodwin, D.C. (1993b)
Comorbidity in psychosis at first hospitalization. Am. J. Psychiatry 150, 752-757. Strakowski, S.M., Flaum, M., Tohen, M., Amador, X. and DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders (1994) Substance abuse in psychotic disorders: associations with affective syndromes. Schizophr. Res. 14, 73-81. Strakowski, S.M., Lonczak, H.S., Sax, K.W., West, S.A., Crist, A., Mehta, R. and Thienhaus, O.J. (1995) The effects of race on diagnosis and disposition from a psychiatric emergency service. J. Clin. Psychiatry 56, 101-107. Strakowski, S.M., McElroy, S.L., Keck, P.E., Jr. and West, S.A. (1996) Racial influence on diagnosis in psychotic mania. J, Affect. Disord. 39, 157-162.
Schizophrenia Research 21 (1996) 117-124
Racial differences in the diagnosis of psychosis 1 Stephen M. Strakowski a,,, Michael Flaum b, Xavier Amador c, H. Stefan Bracha d, Anand K. Pandurangi e, Delbert Robinson f, Mauricio Tohen g a Psychotic Disorders Research Program, Department of Psychiatry, University of Cincinnati College of Medicine, 231 Bethesda Avenue, P.O. Box 670559, Cincinnati, OH 45267-0559, USA b Department of Psychiatry, University of Iowa, Iowa City, IA, USA c Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA d Department of Psychiatry, University of Hawaii, Burns School of Medicine, Honolulu, HL USA e Division of Inpatient Psychiatry, The Medical College of Virginia, Richmond, VA, USA f Long Island Jewish Medical Center-Hillside Hospital, New York, NY, USA g Bipolar and Psychotic Disorders Program, McLean Hospital, Belmont, MA, USA Received 18 December 1995; revision 4 April 1996; accepted 11 April 1996
Abstract
In clinical populations, it has been reported that African-American patients are more likely to receive a diagnosis of schizophrenia than similar Caucasian patients. Factors contributing to this racial discrepancy are poorly defined. The authors examined the hypothesis that racial differences in severity of first-rank symptoms of schizophrenia contribute to this diagnostic difference. Patients were recruited as part of the DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders, and evaluated using a structured rating instrument. Symptom and diagnostic comparisons were performed between black and white patients. Black patients were significantly more likely than white patients to be diagnosed with schizophrenia and less likely with psychotic depression. Racial differences in symptom profiles were observed with black patients demonstrating more severe psychotic symptoms, in general, and first-rank symptoms, specifically. There were no racial differences in rates of affective syndromes or severity of affective symptoms. Racial disparity in diagnosis of psychotic patients may be in part secondary to more severe first-rank symptoms in black patients, causing clinicians to stray from DSM-III-R criteria.
Keywords." Schizophrenia; Psychosis; Affective disorders; Race; First-rank symptoms
1. Introduction
In clinical settings, it has been observed that A f r i c a n - A m e r i c a n patients are disproportionately * Corresponding author. Tel.: (1-513) 558-1132; Fax: (1-513) 558-4805. ~Presented in part at the International Congress on Schizophrenia Research, April, 1995. 0920-9964/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved PII S0920-9964 (96) 00041-2
diagnosed with schizophrenia, c o m p a r e d to similar Caucasian patients, with a corresponding underdiagnosis o f affective syndromes (Neighbors et al., 1989; Mukherjee et al., 1981; Strakowski et al., 1993a, 1995, 1996; L a w s o n et al., 1994). These racial differences in diagnosis tend to decrease with strict adherence to diagnostic criteria, however (Keisling, 1981; Simon and Fleiss, 1973; Mukherjee et al., 1981). Moreover, in the recent
118
Stephen M. Strakowski et al./Sch&ophrenia Research 21 (1996) 117-124
Epidemiologic Catchment Area study there were no racial differences observed in the prevalences of major psychotic disorders after controlling for sociodemographic variables (Robins and Regier, 1991). By providing syndrome descriptions through the widespread use of DSM-III, and subsequently DSM-III-R and DSM-IV, it was hoped that these racial discrepancies in clinical diagnosis would diminish (Adebimpe, 1981; Neighbors et al., 1989). This provision does not appear to have been entirely effective, as recent studies continue to show excess rates of schizophrenic diagnoses in African-Americans (Strakowski et al., 1993b, 1995, 1996; Lawson et al., 1994). The reasons for this racial disparity in diagnosis are unclear, but have been hypothesized to be, at least in part, due to racial differences in the symptomatic presentations of affective and psychotic disorders (Adebimpe, 1981; Neighbors et al., 1989). Indeed, previous investigators have reported increased frequency and severity of hallucinations, paranoia and other psychotic symptoms in black as compared to white patients (Helzer, 1975; Adebimpe et al., 1981, 1982; Mukherjee et al., 1981; Lawson et al., 1984). These findings raise the possibility that psychotic symptoms that are associated with schizophrenia, such as the so-called first-rank symptoms of schizophrenia, may be more common in black than white patients and, therefore, could contribute to racial differences in diagnosis. Schneiderian first-rank symptoms have been widely used to make the diagnosis of schizophrenia and continue to be prominent in current classification systems (Schneider, 1959; Flaum and Andreasen, 1991). First-rank symptoms include auditory hallucinations of voice repeating or commenting on the patient's thoughts or behavior, two or more voices discussing the patient in the third person, and delusions of thought insertion or withdrawal, thought broadcasting, the sensation of being controlled by an external force and delusional perceptions. Several studies have seriously questioned the specificity of these symptoms for schizophrenia (Carpenter et al., 1973; Carpenter and Strauss, 1974; Pope and Lipinski, 1978; Andreasen and Flaum, 1991), but they continue to be used clinically for diagnosis. Thus, if African-American
patients with psychosis express first-rank symptoms more commonly or more severely than Caucasian patients, this might contribute to the increased rate of schizophrenia diagnosed in black patient samples. There have been few studies that have specifically examined racial differences in first-rank symptoms. The DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders was a multi-site study designed to test the reliability and concordance of several diagnostic criteria sets for the nonaffective psychotic disorders to use in DSM-IV (Flaum et al., 1996). In this Field Trial, patients with psychosis were evaluated using a semi-structured rating instrument designed to assess psychotic and affective symptoms, and diagnoses were made from those ratings with the various diagnostic criteria sets. This Field Trial dataset provides a unique opportunity to examine racial differences in the presentation of psychosis that may contribute to the higher rates of schizophrenia diagnosed in black patients in clinical samples by providing a large number of carefully evaluated patients. With these considerations in mind, we analyzed this dataset to determine whether racial differences in ratings of first-rank symptoms contribute to differences between black and white patients in rates of schizophrenia. Specifically, we tested the following hypotheses: (1) black patients in the Field Trial would have higher rates of schizophrenia diagnoses than white patients; and (2) black patients would receive higher ratings on first-rank symptoms.
2. Methods
2.1. Subjects Patients were recruited for the DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders as described elsewhere (Flaum et al., 1996). Briefly, patients were included if they demonstrated at least a mild degree of psychosis, and all subjects provided written informed consent in order to participate. Patients were excluded by a history of severe drug use that clouded the current diagnostic picture, if psychotic symptoms
Stephen M. Strakowski et al./Schizophren& Research 21 (1996) 117-124
appeared to be entirely secondary to a non-psychiatric medical cause or substance abuse, by a history of mental retardation, or if they could not be psychiatrically assessed. It was specified that there was to be no relationship between the probability of recruitment and the patterns of psychopathology, except that cases meeting criteria for a full affective syndrome were to be accepted at a lower rate (approximately 1:2). Racial comparisons were made only between patients designated as black or white, as the numbers of subjects with other racial designations were too small for meaningful analysis. (We chose to use the terms 'black' and 'white' rather than 'African-American' and 'Caucasian', as the former are how the races were designated on the Field Trial form.) The Mexican and the Australian sites were excluded from this analysis because of the racial homogeneity of those samples. 2.2. Raters
Forty raters participated in this study across the seven US sites. Twenty-seven were male and 13 were female. Thirty-four (85%) of the raters were white, non-Hispanic, two (5%) were Hispanic, two were of Middle-Eastern descent (5%; India, Pakistan) and the remaining two (5%) were Asian. Twenty-five raters were psychiatrists (13 postresidency, 12 residents or fellows), four were PhD psychologists and the remaining 11 were master and bachelor degree research assistants. The raters had a mean of 6 (SD 5) years working regularly with patients with psychotic disorders, and over 70% had prior experience using structured and semi-structured psychiatric interviews. 2.3. Clinical assessment
Using the semi-structured interview developed for the Field Trial, patients were evaluated for a wide range of psychiatric symptoms and behaviors. Current positive psychotic symptoms were rated on a 6-point ordinal scale (0 = none to 5 = severe) and included: delusions classified as persecutory, jealous, grandiose, somatic, referential, thought insertion, thought withdrawal, thought broadcasting, being controlled, perceptual, and other;
119
hallucinations classified as auditory, voices commenting, voices conversing, voices referred from body, thought echo, visual and other; formal thought disorder classified as derailment, tangentiality, incoherence, illogicality, neologisms, circumstantiality and poverty of content; and disorganized behavior including inappropriate sexual/social behavior, unusual clothing/ appearance, aggression/agitation, stereotypy and inappropriate affect. Negative symptoms (including affective flattening, alogia, avolition/ apathy and asociality) and catatonia were rated on the same ordinal scale. Current affective symptoms, taken from the DSM-III-R criteria for mania and depression, were rated dichotomously as present or absent. Affective syndromes (depression and mania) were also identified as present or absent according to whether patients met the respective syndrome criteria as defined in DSM-III-R. Current psychoactive substance use was rated on an ordinal scale as follows: 0--no use; 1 = experimental or occasional use; 2=maladaptive use; and 3 = abuse or dependence. For this current analysis, alcohol or drug abuse was rated as present if the alcohol or drug use score was greater than one, otherwise it was considered absent. A detailed analysis of substance abuse in this sample has been published previously (Strakowski et al., 1994). Following the completion of symptom ratings, raters were then instructed to apply the results of this evaluation to diagnose subjects with various diagnostic criteria sets (e.g., DSM-III, ICD-10) (Flaum et al., 1996). Most patients were evaluated by two raters to evaluate diagnostic reliability. Except for analyses of reliability, all information for each patient used for this analysis was that recorded by the primary rater. A more detailed analysis of diagnostic reliability has been published elsewhere (Flaum et al., 1996). 2.4. Statistical analysis
All analyses were performed on the Statistical Analysis System for the Personal Computer (SAS Institute, Cary, NC 1991). The hypothesized associations between race and diagnosis were analyzed using logistic regression adjusting for age, sex,
120
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
education, occupational status and site. Adjusted Odds Ratios (ORa) and 95% Confidence Interval (95% C1) were calculated from this analysis. To determine whether race was associated with reliability of the principal psychotic disorder diagnosis, kappa statistics (Cohen, 1968) were calculated for agreement of diagnoses for both the white and black patient subsets. Racial differences in symptoms were analyzed using a multivariate analysis of covariance (MANCOVA) adjusting for diagnosis, age, sex, education, alcohol and drug abuse. These covariates were chosen as they may confound observed racial differences in psychopathology (Neighbors et al., 1989). The MANCOVA permits determination of significant group differences in symptom profiles, but does not identify specific symptom differences. Thus, effect sizes for individual symptoms were calculated to determine which specific symptoms contributed to racial differences in symptom profiles. Effect size, d~, expresses the magnitude of the difference between group mean scores in terms of standard deviation units (Cohen, 1977). Specifically, ds =1~'1-X21/SD, where -~1 = mean of group one, -~2 = m e a n of group 2 and SD = standard deviation of the overall sample. In order to estimate effect sizes for individual variables adjusted for covariates, an adjusted leastsquares mean score for each racial subgroup and the root mean square error of the symptom were entered into the above equation. Effect sizes were calculated, rather than univariate multiple comparisons, for several reasons. First, post-hoc significance tests are binary decisions based on statistical criteria rather than the potential clinical importance. In contrast, effect size provides a direct estimate of the magnitude of the differences between two groups. Second, significance tests are dependent on sample size, so that even small clinical effects can be deemed 'significant' with a large enough patient sample. Effect size is independent of sample size, and therefore provides a better estimate of the magnitude of group differences. Third, post-hoc significance tests do not permit determination of the relative effects of different symptoms on the overall symptom difference. These tests only determine whether a given symptom is or is not significantly different between the
two groups (i.e., p < 0.05). Effects sizes, in contrast, permit determination of which symptoms most contribute to symptom profile differences. Finally, effect size calculations are not subject to Type I statistical errors, which is a limitation of even the best post-hoc test. Thus, for this particular analysis, in which we wished to determine whether overall symptom differences were present between racial groups, and then identify which symptoms most contributed to that difference, specifically whether first-rank symptoms contributed to the difference, the use of a MANCOVA followed by the calculation of effect sizes was preferred (Cohen, 1977). To interpret effect sizes, Cohen (1977) refers to a ds=0.2 as a small-effect size, a ds=0.5 as a medium-effect size and d~=0.8 as a large-effect size. In general, significant results in the behavioral sciences tend to exhibit small to moderate effect sizes.
3. Results
3.1. Demographics The 330 subjects had an average age of 34 years ( S D = 1 2 years) and were 62% male (n=205). Twenty-six percent of the sample was black (n = 86) and the remaining patients were white (n= 244). Patients had a mean educational level of 13 years ( S D = 3 ) , 68% were never married (n=225) and 49% were unemployed (n = 163). Patients had an average age of symptom onset of 24 years (SD = 10 years) and had six hospitalizations (SD = 7). Black patients demonstrated significantly lower levels of education (12.1 (SD=2.7) years versus 13.1 (SD=2.5) years; t=2.9, df=327, p=0.004). There were no other differences between black and white patients on any of these demographic variables. Black patients were unevenly distributed across sites (X2=36.8, df=6, p<0.0001) as follows: University of Iowa (8%), McLean Hospital (11%), Yale University (13%), Long-Island Jewish/ Hillside Hospital (35%), Columbia University (37%), Medical College of Virginia (37%) and the University of Arkansas (46%).
Stephen M. Strakowski et al./Schizophrenia Research21 (1996)117-124 3.2. Diagnosis The D S M - I I I - R diagnostic distribution is listed by race in Table 1. When adjusted for demographic variables, black patients were more likely to be diagnosed with schizophrenia ( O R a = l . 4 , 95% C I = 1.0-1.8; p = 0 . 0 3 ) and less likely to be diagnosed with psychotic depression ( O R a = 2 . 8 , 95% CI = 1.0-7.8; p =0.04). Indeed, only a single black patient received a diagnosis of psychotic depression, even though the rate of current depressive syndromes was nearly equal in both races (24% of black versus 29% of white patients; X2=0.6, d f = 1, p > 0.4). There were also no racial differences in rates o f current manic syndromes (17% black versus 19% white patients; Z2=0.08, d f = l , p > 0 . 7 ) . There were no differences in rater agreement of the D S M - I I I - R psychotic disorder diagnosis between white and black patients ( k a p p a = 0 . 6 8 versus 0.67, respectively). 3.3. Symptoms Significant racial differences were observed in s y m p t o m profiles ( M A N C O V A F = 1.7, d f = 5 9 , 262, p = 0.003; two subjects were excluded due to missing data). The main contributors to this difference were the psychotic symptoms, as no
121
negative or affective s y m p t o m exhibited an effect size (ds) greater than 0.3, and few o f these symptoms even exhibited a d s > 0.1. The effect sizes for first-rank symptoms are listed in Table 2. Hallucinations of voices commenting on the patient's behavior demonstrated the most robust effect size of any variable (ds = 0.57). Other effect sizes greater than 0.3 were observed for the first-rank symptoms of delusions o f thought withdrawal (ds=0.44), thought insertion (ds=0.32) and being controlled (d~=0.32). Other psychotic symptoms with ds > 0.3 included any auditory hallucination (4.0 ( S D = I . 0 ) vs. 3.2 ( S D = I . 5 ) ; d~ =0.48), any visual hallucination (2.0 (SD = 1.8) vs. 1.3 ( S D = 1.7); d , = 0 . 3 9 ) , grandiose delusions (2.1 ( S D = 2 . 0 ) vs. 1.5 ( S D = 1.8); d~ =0.35), incoherence (1.6 ( S D = 2 . 0 ) vs. 0.5 ( S D = I . 2 ) ; d~=0.38) and aggressive behavior (2.9 ( S D = 1.6) vs. 2.3 ( S D = 1.5); d~ =0.30). In all cases, the mean symptom scores for black patients were greater than those for white patients. Thus, the significant racial difference in s y m p t o m profiles resulted from small- and medium-effects from a number of psychotic symptoms, particularly first-rank symptoms, rather than large-effects from one or a few symptoms.
4. Discussion Table 1 Diagnostic distribution by race of patients from the DSM-IV Field Trial for schizophrenia and other psychotic disorders Diagnosis
Schizophrenia Bipolar disorder Schizoaffective disorder Schizophreniform disorder Major depression Delusional disorder Psychosis NOS Other
Black (n = 86) (%)
White (n = 244) (%)
Total (n = 330) (%)
52 (60)a 8 (9) 10 (12) 8 (9) 1 (1) b 2 (2) 3 (4) 2 (2)
117 (48) 30 (12) 26 (11) 16 (7) 20 (8) 13 (5) 12 (5) 10 (4)
169 (51 38 912) 36 (11) 24 (7) 21 (6) 15 (5) 15 (5) 12 (3)
NOS, not-otherwise-specified. aSignificant difference versus white; ORa=l.4, 95% CI= 1.0-1.8; p=0.03. bSignificant difference versus white; ORa=2.8, 95% CI= 1.0-7.8; p =0.04.
In this sample from the D S M - I V Field Trial for Schizophrenia and Other Psychotic Disorders, black patients were more likely than white patients to receive a D S M - I I I - R diagnosis of schizophrenia, Table 2 First-rank symptoms by race of patients from the DSM-IV Field Trial for schizophrenia and other psychotic disorders Symptom
Black White (n =86) (n =244) mean (SD) mean (SD)
Thought insertion 1.7 (1.8) Thought withdrawal 1.4 (1.8) Thought broadcasting 1.5 (1.9) Being controlled 1.9 (1.8) Delusional perception 0.9 (1.3) Voices commenting 2.7 (1.9) Voice conversing 1.9 (2.0)
1.0 (1.6) 0.7 (1.3) 1.0 (1.6) 1.2 (1.7) 0.8 (1.3) 1.5 (1.8) 1.5 (1.8)
Effect size, d, 0.32 0.44 0.28 0.32 0.14 0.57 0.25
122
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
and less likely to be diagnosed with psychotic depression. This racial difference in diagnosis may reflect a tendency by raters to see black patients as sicker, and conversely white patients as less ill, thereby leading to the observed racial differences in diagnostic assignment for both groups. Alternatively, the more severe first-rank symptoms in black patients may have influenced raters away from DSM-III-R criteria to diagnose schizophrenia, even with the criteria immediately available, and even though the rates of affective syndromes were similar between the racial groups. Indeed, there were significant racial differences in symptom profiles, with more severe psychotic symptoms in general, and first-rank symptoms specifically, in black patients. Whether these differences resulted from bias in the rating of symptoms (since the persons performing the ratings and making the diagnoses were the same), or reflect real racial differences in symptomatic presentation of psychosis cannot be determined in this study. Nonetheless, the prominent use of firstrank symptoms as diagnostic criteria may lead to racially disproportionate rates of diagnosing schizophrenia, suggesting that further study is needed to clarify racial and cultural differences in the expression of psychosis. As noted, the rate of DSM-III-R depressive and manic syndromes was not different between racial groups, even though black patients were much less likely to be given an affective disorder diagnosis, particularly of psychotic depression. Indeed, although 24% of the black patients had a current depressive syndrome identified, only a single patient (1%) was diagnosed with psychotic depression (compared with 29 and 8%, respectively, in white patients). The diagnoses of psychotic depression, schizoaffective disorder (depressed type) and schizophrenia with secondary depression lack clear phenomenological boundaries, which makes differentiating among these conditions quite difficult, even when using operationalized criteria sets (Siris et al., 1978). Thus, if the reliability and validity of distinguishing among these similar conditions is limited in general, then diagnoses of these patients may have been more susceptible to the influence of (nondiagnostic) symptom differences in this study specifically.
Other factors contributing to racial bias in diagnosis must also be considered. The cultural gap between the primarily white raters assessing black patients in this sample may have resulted in assigning pathology where it did not belong; e.g., misinterpreting culturally based jargon as thought disorder. Without direct measures of cultural misperception, however, this study could not directly assess these issues. It is also possible that the schizophrenia diagnosis was used as a pejorative label for black patients reflecting an underlying prejudice among the raters. Given the large number of clinical evaluators and the multi-site design, it seems unlikely that systematic prejudice alone explains the observed racial differences. Several limitations to this analysis must be considered when interpreting results. First, the DSM-IV Field Trial was primarily designed to evaluate the reliability and concordance of various diagnostic criteria sets for nonaffective psychotic disorders. Thus, as with any secondary analysis, conclusions are limited for those hypotheses that were not primary and, therefore, the results of this analysis should be viewed as preliminary. Specific information that might have clarified further those factors that influence diagnosis in different racial groups was not obtained, so could not be examined (e.g., racial preconceptions of raters). On the other hand, post-hoc analyses provide some protection against rater bias toward the tested hypotheses. A second limitation is the lack of generalizability of this sample to other samples of psychotic disorders. By identifying primarily nonaffective psychosis, the relative prevalence of affective psychoses was lower than would be expected in an epidemiological sample, which may have contributed to racial differences that would not be present with more general recruitment. Furthermore, the exclusion of significant substance abusers limits comparisons to other patient samples where substance use rates are higher (Regier et al., 1990; Strakowski et al., 1993a), and since substance abuse rates differ among racial groups in the US (Robins and Regier, 1991), this could have led to a racial sampling bias. Finally, most of the patients in this sample were hospitalized (Flaum et al., 1996), so racial differences in diagnosis may have reflected racial differences in factors leading to hospitalization.
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
These limitations are s o m e w h a t compensated for by the large n u m b e r o f patients and the multi-site design which strengthens the validity o f the findings. Despite these limitations, this study suggests that the disproportionate rate o f diagnosis o f schizophrenia in black patients m a y be, in part, due to m o r e severe first-rank s y m p t o m s o f schizophrenia in that subgroup, causing clinicians to stray f r o m diagnostic criteria. Thus, in multiculrural patient samples, first-rank s y m p t o m s o f schizophrenia m a y be m o r e culturally based than diagnostically specific. F u r t h e r research is clearly warranted.
Acknowledgment The D S M - I V Field Trial W o r k Group-Site C o o r d i n a t o r s were: Xavier A m a d o r , P h D and Jack G o r m a n , M D (Columbia University, N e w York, N Y ) ; H. Stefan Bracha, M D (University o f A r k a n s a s for Medical Sciences, Little R o c k , A R ) ; William Edell, P h D and T o m M c G l a s h a n , M D (Yale Psychiatric Institute, N e w Haven, C N ) ; A n a n d Pandurangi, M D and K e n n e t h Kendler, M D (Medical College o f Virginia, R i c h m o n d , VA); Delbert R o b i n s o n , MD and Jeffrey Lieberman, M D (LIJ-Hillside Medical Center, N e w York, N Y ) ; A l f o n s o Ontiveros, M D , MSc (Autonomous University of Nuevo Leon, Mexico); Mauricio Tohen ( M c L e a n Hospital, Belmont, M A ) ; Michael Flaum, M D and N a n c y C. Andreasen, M D , P h D (University o f Iowa, I o w a City, IA). The authors also t h a n k Stephan Arndt, P h D for his statistical assistance and William B. Lawson, M D for his c o m m e n t s on this manuscript. This research was supported in part by: N I M H G r a n t MH47200, M H C R C G r a n t MH43271, Scottish Rite Schizophrenia Research P r o g r a m N.M.J. G r a n t ( S M S ) and a grant f r o m the Ohio D e p a r t m e n t o f Mental Health (SMS).
References Adebimpe, V.R. (1981) Overview: white norms and psychiatric diagnosis of black patients. Am. J. Psychiatry 138, 279-285.
123
Adebimpe, V.R., Klein, H.E. and Fried, J. (1981) Hallucinations and delusions in black psychiatric patients, J. Natl. Med. Ass. 73, 517-520. Adebimpe, V.R., Chu, C.C., Klein, H.E. and Lange, M.H, (1982) Racial and geographic differences in the psychopathology of schizophrenia. Am. J. Psychiatry 139, 888-891. Andreasen, N.C. and Flaum, M. (1991) Schizophrenia: The characteristic symptoms. Schizophr. Bull. 17, 27-49. Carpenter, W.T., Strauss, J.S. and Muleh, S. (1973) Are there pathognomonic symptoms in schizophrenia. Arch. Gen. Psychiatry 28, 847-852. Carpenter, W.T. and Strauss, J.S. (1974) Cross-cultural evaluation of Schneider's first-rank symptoms of schizophrenia: A report from the International Pilot Study of Schizophrenia. Am. J. Psychiatry 131,682-687. Cohen, J. (1968) Weighted kappa: nominal scale agreement with provision for scaled disagreement or partial credit. Psychol. Bull. 70, 213-220. Cohen, J. (1977) Statistical power analysis for the behavioral sciences. New York: Academic Press. Flaum, M. and Andreasen, N.C. (1991)Diagnostic criteria for schizophrenia and related disorders: Options for DSM-IV. Schizophr. Bull. 17, 133-156. Flaum, M., Amador, X., Gorman, J., Bracha, H.S., Edell, W., McGlashan, T., Pandurangi, A., Kendler, K., Robinson, D., Lieberman, J., Ontiveros, A., Tohen, M., McGorry, P., Tyrrell, G., Arndt, S. and Andreasen, N.C. (1996) The DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders. Am. J. Psychiatry, in press. Helzer, J.D. (1975) Bipolar affective disorder in black and white men: A comparison of symptoms and familial illness. Arch. Gen. Psychiatry 32, 1140-1143. Keisling, R. ( 1981) Underdiagnosis of manic-depressive illness in a hospital unit. Am. J. Psychiatry 138, 672-673. Lawson, W.B., Yesavage, J.A. and Werner, P.D. (1984) Race, violence, and psychopathology. J. Clin. Psychiatry 45, 294-297. Lawson, W.B., Hepler, N., Holiday, J. and Cuffel, B. (1994) Race as a factor in inpatient and outpatient admissions and diagnosis. Hosp. Commun. Psychiatry 45, 72-74. Mukherjee, S., Shukla, S., Woodle, J., Rosen, A.M. and Olarte, S. ( 1981) Misdiagnosis of schizophrenia in bipolar patients: a multiethnic comparison. Am. J. Psychiatry 138, 279-285. Neighbors, H.W., Jackson, J.S., Campbell, L. and Williams, D. (1989) The influence of racial factors on psychiatric diagnosis: a review and suggestions for research. Commun. Ment. Health J. 25, 301-311. Pope, H.G., Jr. and Lipinski, J.F. (1978) Diagnosis in schizophrenia and manic-depressive illness: A reassessment of the specificity of 'schizophrenic' symptoms in the light of current research. Arch. Gen. Psychiatry 35, 811-828. Regier, D.A., Farmer, M.E., Rae, D.S., Locke, B.Z., Keith, S.J., Judd, LL. and Goodwin, F.K. (1990) Comorbidity of mental disorders with alcohol and other drug abuse: Results from the Epidemiologic Catchment Area (ECA) Study. J. Am. Med. Ass. 264, 2511-2518. Robins, L.N. and Regier, D. (Eds.) (1991) Psychiatric
124
Stephen M. Strakowski et al./Schizophrenia Research 21 (1996) 117-124
Disorders in America: the Epidemiologic Catchment Area Study. The Free Press, New York, NY. Schneider, K. (1959) Clinical Psychopathology. (Hamilton, M.W., translator). Grune and Stratton, New York, NY. Simon, R. and Fleiss, J. (1973) Depression and schizophrenia in hospitalized patients. Arch. Gen. Psychiatry 14, 475-481. Sifts, S.G., van Kammen, D.P. and Docherty, J.P. (1978) Use of antidepressant drugs in schizophrenia. Arch. Gen. Psychiatry 35, 1368-1377. Strakowski, S.M., Shelton, R.C. and Kolbrener, M.L. (1993a) The effects of race and comorbidity on clinical diagnosis in patients with psychosis. J. Clin. Psychiatry 54, 96-102. Strakowski, S.M., Tohen, M., Stoll, A.L., Faedda, G.L., Mayer, P.V., Kolbrener, M.L. and Goodwin, D.C. (1993b)
Comorbidity in psychosis at first hospitalization. Am. J. Psychiatry 150, 752-757. Strakowski, S.M., Flaum, M., Tohen, M., Amador, X. and DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders (1994) Substance abuse in psychotic disorders: associations with affective syndromes. Schizophr. Res. 14, 73-81. Strakowski, S.M., Lonczak, H.S., Sax, K.W., West, S.A., Crist, A., Mehta, R. and Thienhaus, O.J. (1995) The effects of race on diagnosis and disposition from a psychiatric emergency service. J. Clin. Psychiatry 56, 101-107. Strakowski, S.M., McElroy, S.L., Keck, P.E., Jr. and West, S.A. (1996) Racial influence on diagnosis in psychotic mania. J, Affect. Disord. 39, 157-162.