In order to diagnose a person with schizophrenia, a clinician must use the diagnostic tools such as the DSM IV or the ICDIO. However, for the most effective treatment or a thorough investigation a clinician or researcher commonly uses a rating scale to determine exactly from which of the many signs and symptoms a patient with schizophrenia is suffering. The Brief Psychiatric Rating Scale (Overall and Gorham, 1962) is a widely used rating scale, but it covers a wide selection of symptoms and is not designed to cover specific symptoms of schizophrenia in detail (Our et al., 1991). There is an overlap among items, it lacks clear operational definitions, and there is not a clear link between the items on the scale and the symptoms of schizophrenia (Manchanda et al., 1989). In addition, Krawieka et al. (1977) point out that it is not sensitive to changes over time. Krawieka et al. (1977) wanted to create a scale that was short and easily administrable yet could be used reliably to assess chronic patients while being sensitive to any changes in symptom status. Previous scales other than the BPRS [the Wittenbom (Wittenbom, 1955), the Mental Schedule (Spitzer et al., 1964), the In- Patient Multi-dimensional Psychiatric Scale (IMPS) (Lorr et al., 1963), the Present State Examination (Wing et al., 1967), The Clinical Interview Schedule (Goldberg et al., 1970)] were considered too long to be useful as such an instrument (Krawieka et al., 1977). As a result a 5-point rating scale was created which was simple to administer, was sensitive to symptom changes in the patient, and was a reliable classification of patients according to Wing’s Scales. Half of the ratings are based on the patient’s replies to questions and the other half are based on the rater’s clinical observation of abnormal phenomena. The Krawieka Manchester Scale is reported to provide the best compromise among conciseness, specificity of symptoms of schizophrenia, and sensitivity to change (Manchanda et al., 1989).
The Comprehensive Psychopathological Rating Scales (GPRS) as designed to rate items sensitive to change with treatment (Asberg et al., 1978). The scale is written with clear descriptions and guidelines for rating severity (Manchanda et al., 1989). It is longer than the Manchester scale and covers some of the positive and the negative symptoms of schizophrenia but also covers items that would not be considered primary symptoms of schizophrenia such as suicidal thoughts, sleepiness and aches and pains.
The Scale for the Assessment of Negative Symptoms (SANS) (Andreasen, 1983) was the first rating scale offering a thorough assessment of negative signs in schizophrenia (Andreasen, 1989). Poverty of speech, poverty of content of speech, affective blunting, avolition, ahedonia, and attentional impairment were combined to give a reliable rating of the ‘negative’ features of schizophrenia. The Scale for the Assessment of Positive Symptoms (SAPS) (Andreasen, 1984) allows for a comprehensive assessment and global ratings of hallucinations, delusions, positive formal thought disorder (derailments, tangentiality, incoherence and distractible speech) and bizarre behaviour. These two scales offer a complete set of rating scales to measure the signs and symptoms of schizophrenia that are sensitive to changes over time. Although these scales are longer than the Krawieka Manchester Scale (Krawieka et al., 1977) they offer more thorough coverage of the symptoms, but with practice can be administered relatively quickly.
Factor analytic studies from the Iowa Group have shown that the negative signs in the SANS, omitting attention and inappropriate affect, load as a single cohesive factor while the positive symptoms of the SAPS load on two main factors, disorganized symptoms (including inappropriate affect from the SANS) and florid psychotic symptoms (Andreasen 1983, 1984; Andreasen and Grove 1986; Andreasen and Olson, 1982;
Andreasen et al., 1995; Amdt et al., 1991; Miller et al., 1993) similar to the Liddle division (1987a,b).
Other rating scales have been developed over time. A few of the more prevalent are the Lewine, Fogg and Meltzer Scale, (Lewine et al., 1983), which combines items from the Nurses Observation Scale for Inpatient Evaluation (Honigfeld et al., 1966) and the Schedule for Affective Disorders and Schizophrenia (Endicott and Spitzer, 1978); the Pogue-Geile and Harrow Negative Symptom Scale (1985), which is a negative symptom scale derived from the Behaviour Rating Schedule of the Psychiatric Assessment Interview (Carpenter et al., 1976); and the Positive and Negative Syndrome Rating Scale (PANNS) (Kay et al., 1992). Kay and colleagues (1992) developed the PANNS in order to provide a rating scale without a strict positive/negative dichotomy. The PANNS offers a 30-item scale for which the symptoms break down into four symptom complexes, negative, positive, excited and depressed. The PANNS is superior to the SAPS/SANS, according to Merriam, Kay et al. (1990) because of its "(1) standardized interview; (2) detailed operational criteria for all items at rating levels; (3) parallel assessment of positive, negative, and general symptoms to permit direct comparisons; (4) selection of ‘primary’ negative symptoms (Carpenter et al., 1985), which is essential for construct and content validity (Zubin 1985); and (5) intensive psychometric standardization that has supported the scale’s inter-rater, retest, and internal reliability as well as the contstruct, concurrent, and predictive validity" (Kay et al., 1987, 1988) (pl83).
Further analysis by the PANNS study group (White et al., 1997) used factor analysis on a sample of over 1,000 patients with schizophrenia, yet none o f their models fit the data for such a large sample. Half of the subjects’ data were used for reanalysis and the
group confirmed a five-factor model including positive, negative, dysphoric mood, activation, and autistic preoccupation.
With so many scales rating the different symptoms of schizophrenia comparisons of the more popular ones have emerged. Gur et al. (1991) examined the reliability of the BPRS, the SANS/SAPS and Carpenters deficit/ non-deficit distinction. One drawback o f the BPRS is that it tends to give an overall rating of severity of schizophrenia rather than specifying the symptom profile of the patient (Gur et al., 1991). The SANS/SAPS and the BPRS measured corresponding dimensions of schizophrenia symptomatology without direct overlap. Cluster analysis revealed that most patients with low negative symptom scores had non-deficit syndrome, whereas patients with high negative symptom scores had deficit syndrome. Dollfus and Brazo (1997) used cluster analysis to compare the SANS/SAPS and the PANNS. Both sets of scales produced a four- cluster solution, with positive, negative, mixed and mild clusters. Further analysis of these data revealed a five-cluster solution, which divided the positive cluster into a disorganized and a non-disorganized cluster on both sets of scales. Based on the findings of comparison studies the different scales are generally reliable and valid, although some discrepancies exist (Fenton and McGlashan, 1992), for example the SAPS/SANS includes attention as a ‘negative’ sign whereas it is not classified as such in the PANSS or BPRS. Because the subtype classification is still hotly debated, i.e., positive/ negative, deficit/ non-deficit, psychomotor-poverty/ psychotic/ disorganized, the rating scales appear to be most usefiil for symptom ratings rather than a subtype classification.