Broadscope Measures Of Symptom Severity In Schizophrenia

As reviewed in Table 5, multiple specific rating scales have been offered for the measurement of symptoms such as positive or negative symptoms. An alternative approach to symptom measurement is the use of broad-scope measures of global symptom severity. One of the most widely employed rating scales in psychiatric research is the 18-item BPRS (31), mentioned earlier. The scale has gained extensive use in psychopharmacology research. The 18 items contained within the BPRS, listed in Table 6, are scored from 1 (not present) to 7 (extremely severe) following a 20-30-minute clinical interview of the patient. Although the scale was developed with the goal of measuring psychopathology found in a range of severe psychiatric disorders, it has been used most extensively in schizophrenia research. Each item in Table 6 has detailed definitions that should be used in the clinical applications of the scale (31). Various combinations of items have been thought to provide an

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Table 5 Knowing Which Symptoms Are Which

Positive symptoms

1. Defined as grossly abnormal experiences/behaviors not typically observed in nonpatient groups

2. Typically observed in the acute phase of the disorder and represent a primary target of antipsychotic medications

3. Includes delusional ideation, hallucinations, and other anomalous perceptual experiences

4. Measured by scales such as Scale for the Assessment of Positive Symptoms (SAPS)

Thought disorder

1. Defined as discontinuity of thought resulting in fragmented of illogical speech and grossly disorganized behavior

2. Typically observed in acute phase of disorder with residual thought-disorder symptoms associated with poor prognosis

3. Symptoms include neologisms, derailment, thought blocking, circumstantiality

4. Measured by the Scale for the Assessment of Thought, Language, and Communication (TLC) and other techniques

Negative and deficit symptoms

1. Defined as symptoms that are altered or diminished in patients but typically present in the general population

2. Commonly include features such as affective flattening, avolition, affective nonresponsivity

3. Negative symptoms may be present over the entire course of the illness, and represent one of the most difficult to treat aspects of the disorder

4. Deficit symptoms include enduring deficits in intrapsychic, interpersonal, and instrumental functioning

5. Related to poor social outcome, including skill acquisition

6. Negative symptoms measured by the Schedule for the Assessment of Negative Symptoms and other scales; deficit symptoms measured by the Quality of Life Scale acceptable rapid assessment of features of negative and positive symptoms (32,41).

A relatively new broad-scope rating instrument for the assessment of schizophrenia is the PANSS (33). As explained above, this scale contains a modified and behaviorally anchored version of the 18 core BPRS items plus 12 additional items (33). This instrument seeks to provide expanded coverage of negative symptoms as well as other positive and general psychiatric symptoms commonly found in schizophrenia (33). As reviewed below, the instrument has been included in factor-analytic work seeking unique symptom clusters in schizophrenia.

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Table 6 Symptom Coverage Provided by the Brief Psychiatric Rating Scale (items are scored on a seven-point scale ranging from not present to extremely severe)

1. Somatic concern

2. Anxiety

3. Emotional withdrawal

4. Conceptual disorganization

5. Guilt feelings

6. Tension

7. Mannerisms and posturing

8. Grandiosity

9. Depressed mood

10. Hostility

11. Suspiciousness

12. Hallucinatory behavior

13. Motor retardation

14. Uncooperativeness

15. Unusual thought content

16. Blunted affect

17. Excitement

18. Disorientation

Source: Adapted from Ref. 30.

Use of the PANSS has been growing in clinical treatment trials in schizophrenia. A structured clinical interview has been offered to assist in the assessment of symptoms for completing the scale. The PANSS and supporting materials are available from Multi-Health Systems, 908 Niagara Falls Blvd., North Tonawanda, NY 14120.

Defining Symptom Clusters in Schizophrenia

A major goal of research in symptom expression in schizophrenia is the identification of replicable clusters of symptoms that tend to be associated with one another and are, at least to some degree, independent of other groups of symptoms. To achieve this goal, researchers employ statistical techniques called factor analysis—often using a specific technique called principal-components analysis, which generates groupings of symptoms that are independent of one another. Such studies can be either exploratory (entering large numbers of items derived from many patient observations to determine relationships) or

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u confirmatory (testing whether specific hypothesized models of clusters of symptoms can be fit from the clinical ratings).

The findings of factor-analytic work are obviously dependent on the type of symptom measures entered into the analysis. In reviewing this work it is important to note that research restricted to the evaluation of core schizophrenic/psychotic-disorder symptoms will yield different results than work employing rating scales (e.g., BPRS and PANSS) that include symptoms that are not specific to schizophrenia (e.g., depressed mood).

Numerous works have performed factor analyses of ratings of schizophrenic patients who were evaluated with the SANS and SAPS. These works have generally identified three major symptom factors (42): 1) negative symptoms (e.g., SANS measures such as affective flattening, avolition), 2) positive psychotic symptoms (e.g., delusions, hallucinations), and 3) what has been deemed a disorganization factor (e.g., formal thought disorder). Table 7 provides the factor loading for the global SANS and SAPS items that were entered into analysis and demonstrates the relative factor loadings for the measures.

There has been significant clarification of the nature of some symptoms in schizophrenia. For example, inappropriate affect may well relate more to disorganized symptoms than to negative symptoms (the

Table 7 Varimax Rotated Factor Structure of the Global Items from the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms

Factor

Table 7 Varimax Rotated Factor Structure of the Global Items from the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms

Factor

Symptom

Negative

Disorganized

Psychotic

Avolition

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