Diagnostic significance of Schneider's first-rank symptoms in schizophrenia. Comparative study between schizophrenic and nonschizophrenic psychotic disorders V Peralta and MJ Cuesta The British Journal of Psychiatry 1999 174: 243-248 Access the most recent version at doi:10.1192/bjp.174.3.243
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B R I T I S H J O U R N A L OF P S Y C H I A T R Y ( 1 9 9 9 ) . 174. 2 4 3 - 2 4 8
Diagnostic significance of Schneider's first-rank symptoms in schizophrenia Comparative study between schizophrenic and non-schizophrenic psychotic disorders VICTOR PERALTA and MANUEL J. CUESTA
disorders. Schizophrenia was diagnosed according to three criteria: DSM - Ill- R
A number of symptom approaches have been proposed for the diagnosis of schizophrenia throughout the last 100 years. Among the most popular are Schneider's (1959) first-rank symptoms (FRSs). The influence of FRSs on diagnosis has been enormous because they have been included in the most influential operative diagnostic criteria for schizophrenia, such as DSMIV (American Psychiatric Association, 1994) and particularly ICD-10 (World Health Organization, 1992). Although there is some evidence that FRSs may have some discriminative value in distinguishing schizophrenia from other psychiatric disorders, the diagnostic value cast on these symptoms varies highly among studies (Carpenter et al, 1973; Wing & Nixon, 1975; Goldman et al, 1992).
broad, DSM- Ill- R narrow and Feighner, the latter being considered as the gold standard because it does not give particular emphasis to FRSs.
METHODOLOGICAL CONCERNS IN PREVIOUS STUDIES
Background Despitethe lack of consistent empirical support, modern diagnostic criteria of schizophrenia give particular emphasis to Schneider'sfirstrank symptoms (FRSs).
Aims To examine the diagnostic significance of FRSs for schizophrenia by trying to overcome the limitations of previous studies. Methods This study examined the diagnostic accuracy of FRSs for schizophrenia in 660 in-patientswith the full spectrum offunctional psychotic
Results FRSs were highly prevalent in both schizophrenia and non-schizophrenic psychoses.The likelihood ratios (and 95% CI) ofone or more FRSs for Feighner, DSM- Ill- R narrow and DSM-Ill- R broad schizophrenia were 1.06 (0.941.20) 1.23 (1.09-1.39) and 1.73 (1.44-2.08) respectivelyThesedata indicatethat FRSs do not significantly increase the likelihood of having schizophrenia.
Much of the confusion about the diagnostic value of FRSs is mainly due to three factors. First, most of the previous studies have included patients in whom schizophrenia was diagnosed using criteria that strongly rely upon FRSs. Such studies are more likely to report higher rates of FRSs in schizophrenia, thus biasing the results in the direction of a high specificity of FRSs. In this respect, the use of diagnostic criteria for schizophrenia not particularly based upon FRSs would be the 'gold standard' against which the diagnostic value of FRSs Conclusions FRSs are not useful in might be tested. Second, many studies analysing the prevalence of FRSs in nondifferentiating - schizophrenia from other psychoticdisorders. ~ i ~ systems ~ ~ schizophrenic ~ ~ t disorders i ~ have included non-psychotic conditions. However, the for schizophrenia that are heavily basedon diaenostic relevance of FRSs would be to these symptoms may arise from a differentiate schizophrenia from other tautological definition ofthe disorder. psychotic disorders rather than from nonpsychotic disorders. Third, as Geddes et a1 Declaration of interest None. (1996) have recently pointed out, there are no studies of the diagnostic propemes of
-
FRSs meeting the recommended statistical quality criteria for a diagnostic procedure. Owing to these limitations, the extent to which FRSs are useful in the diagnosis of schizophrenia remains largely unknown. Both the continued reliance upon FRSs for diagnosing schizophrenia and the lack of sound studies supporting this view justify a further empirical evaluation of their diagnostic value. The present study aimed to examine the diagnostic significance of FRSs for schizophrenia by trying to overcome the limitations of previous studies.
METHODS Patients The data from this study are part of a broader research project (the Pamplona Study on the phenomenology of functional psychotic disorders) aimed at studying the functional psychosis from a polydiagnostic point of view. In summary, the study comprised 660 subjects with the full spectrum of functional psychotic disorders diagnosed according to DSM-111-R criteria (American Psychiatric Association, 1987) who were consecutively admitted to the Psychiatric Unit of the Virgen del Camino Hospital between 1988 and 1996. All subjects underwent an extensive battery of psychopathological instruments. As the primary tool for clinical assessment and diagnosis, we used the Manual for the Assessment of Schizophrenia (MAS; Landmark, 1982). This is a comprehensive semi-structured interview conceived for assessing symptoms of psychosis, particularly schizophrenia, from a polydiagnostic point of view. The manual originally included items covering 12 different criteria for schizophrenia. We have modified and expanded the MAS to cover information for 10 additional diagnostic systems and for diagnosing all functional psychotic disorders and major mood disorders according to DSM-111-R criteria (Peralta & Cuesta, 1992). Patients were included in the study if they had some of the following symptoms at admission: delusions, hallucinations, marked formal thought disorder, gross disorganised behaviour, severe negative s y m p toms or catatonic symptoms. Exclusion criteria were: demonstrable brain disorders, drug misuse confounding diagnosis, mental retardation, serious medical disease or lack of reliable external sources of information. Patients gave informed consent to be interviewed, and the entire research protocol
CERALTA L CUESTA
was approved by the ethical committee of the hospital. A summary of patients' characteristics is provided in Table 1. Procedure
The main aim of the study was to analyse the diagnostic value of FRSs for schizophrenia, taking non-schizophrenic functional psychosis as the reference group. We used three sets of criteria for schizophrenia: a DSM-IU-R narrow concept (i.e. DSM-111-R schizophrenia), a DSM-IU-R broad concept (i.e. schizophrenia, schizophreniform disorder and schizoaffective disorder) and the Feighner criteria for definite schizophrenia (Feighner et al, 1972). The rationale for analysing a DSM-111-R broad schizophrenia concept was that the three disorders forming this diagnosis share criterion A for schizophrenia and therefore the diagnostic weight given to FRSs. For the purposes of the present study, Feighner's definition was used as the 'gold standard' because it does not give particular diagnostic emphasis to FRSs. Diagnoses were mode at the end of the index admission using all available information. Inter-rater reliability for the MAS variables and diagnosis was studied in 33 patients who were assessed conjointly by the authors. The inter-rater reliability (r) for DSM-111-R and Feighner schizophrenia was 0.88 and 0.76, respectively. For individual DSM-111-R disorders, a consensus diagnosis was made by V.P. and M.J.C. after reviewing all the available information. Assessment of FRSs
First-rank symptoms were assessed by V.P. and MJ.C. using the phenomenological method in the context of one or more clini-
cal interviews conducted within the first five days of admission. Most patients underwent at least two interviews and, when necessary (e.g. the presence of symptoms such as poor collaboration, lack of insight or poverty of speech interfering with the assessment of the subject state), assessment interviews were either delayed or conducted several times. The last month was taken into account to rate the symptoms. Presence or a b sence of FRSs was established on the basis of the criteria provided by the MAS. The MAS comprises 11 standard definitions of FRSs that are highly comparable to Mellor's (1970) classical operational definitions. In addition, we included the symptom of 'made feelings', which was rated according to Mellor's definition. Therefore, a total of 12 FRSs were assessed. The FRSs were also rated using the Scale for the Assessment of Positive Symptoms (SAPS; Andreasen, 1984).
the probabilities of a given test result among patients who do and do not have the disease, and indicates by how much a given diagnostic feature will raise or lower the probability of having the target disorder. A guide for interpreting the magnitude of the likelihood ratio is provided by Jaeschke et a1 (1994): likelihood ratios of one indicate that the diagnostic feature neither increases nor decreases the p r o b ability of having the disorder; ratios between one and two increase the probability to a small and unimportant degree; ratios between two and five indicate a modest (but sometimes important) increase of the probability; ratios of > 5 generate substantial and always clinically significant changes in the probability; and ratios of > 1 0 indicate conclusive changes in the probability.
RESULTS
Statistical analysis
Four basic statistics have been traditionally used to document the accuracy of a diagnostic procedure sensitivity (proportion of patients with schizophrenia having FRSs), specificity (proportion of patients without schizophrenia not having FRSs), positive predictive power (propomon of patients with FRSs having schizophrenia) and negative predictive power (propomon of patients without schizophrenia not having FRSs). A fifth statistic, the likelihood ratio, represents a balance between specificity and sensitivity, thus being the most important measure of the diagnostic usefulness of a feature Uaeschke et al, 1994; Geddes et al, 1996). The likelihood ratio is a ratio of
Psychometric properties of FRSs
The inter-rater reliability (K value) for FRSs was as follows: audible thoughts (0.52), voices arguing (0.70), voices commenting (0.63), delusional perception (0.51), somatic passivity (0.75), made thoughts (0.70), made impulses (0.67), made volition (0.62), made feelings (0.89), thought insertion (0.73), thought withdrawal (0.67) and thought broadcasting (0.87). The K value for the presence of at least one FRS was 0.93. A principal component analysis with oblimin rotation of the 12 FRSs as assessed by the MAS resulted in two highly correlated factors (r=0.45) that explained
Table I Socii-demographicand clinical characteristics of the patients across DSM-Ill-R diagnosis' Schizophrenia (n=352)
Schiwphreniform Schizoaffective disorder disorder (n=88) (n=37)
Gender, n (%)female Age, years Education, years Age at illness onset No. of haspitalisations Illness duration (years) GAF, last year' Duration of index admission (weeks) I. Wues are meam (s.d.). 2. GAF, Gbbai Assessment Functioning W
e (DSM-Ill-R. Avis V).
Mood
disorder (n=S3)
Delusional disorder (n=25)
Brief reactive psychosis (n=ZS)
Atypiul psychosis (n=50)
SCHNEIDER'S FIRST-RANK S Y M P T O M S
53% of the variance. The first factor comprised the delusional symptoms, and the second factor the hallucinatory symptoms plus audible thoughts and delusional perception. Thought broadcasting was loaded in the two factors. Principal component analysis of the seven SAPS FRSs resulted in two correlated factors (r=0.42) that explained 70% of the variance. The factor pattern was very similar to that of the MAS symptoms, with delusional and hallucinatory symptoms loading on separate factors. Internal reliability analysis resulted in alpha coefficients of 0.86 for the 12 MAS symptoms and 0.84 for the seven SAPS symptoms. Both principal component and internal reliability analyses indicated that FRSs represent a relatively homogeneous construct and provide some support for the use of a global measure of it (i.e. the presence of one or more FRSs).
Prevalence of FRSs across psychotic disorders Table 2 presents data on the prevalence of FRSs across DSM-111-R psychotic disorders. In the whole sample the presence of one or more FRS? were documented for 413 (62%) patients. It was apparent that individual FRSs occurred at substantially different rates, with thought broadcasting being the most common (37%) and made impulses and made feelings being the least common (11%). Patients with schizo-
phreniform disorder had the highest frequency rate for at least one FRS (83%) and for most individual symptoms. At the other pole, only two patients (8%) with delusional disorder manifested FRSs. Global prevalence rates were essentially equivalent for schizophrenia and schizoaffective disorder (2=0.19, d.f.=l, NS), but patients with schizophreniform disorder had significantly more FRSs than those with schizophrenia (x2=7.23, d.f.=l, P
