Schizophrenia Research 89 (2007) 119 – 122 www.elsevier.com/locate/schres
The Psychotic Symptom Rating Scales (PSYRATS): Their usefulness and properties in first episode psychosis Richard Drake a,⁎, Gillian Haddock b , Nicholas Tarrier c , Richard Bentall c , Shôn Lewis a a
b
Division of Psychiatry, University of Manchester, 2nd Floor Education and Research Centre, Wythenshawe Hospital, Manchester, M23 9PL, United Kingdom School of Psychological Sciences, University of Manchester, Rutherford House, Manchester Science Park, Lloyd Street North, Manchester, M15 6SZ, United Kingdom c School of Psychological Sciences, University of Manchester, Oxford Road, Manchester, M15 9PL, United Kingdom Received 8 April 2006; received in revised form 14 April 2006; accepted 25 April 2006 Available online 13 November 2006
Abstract The aim of this study was to investigate the reliability, validity and structure of the Psychotic Symptom Rating Scales (PSYRATS) in 257 subjects presenting with acute first episodes of schizophrenia or related disorders. The PSYRATS have been shown to assess dimensions of hallucination and delusions reliably and validly in chronically psychotic patients but not in first episode patients. Item reliability was investigated and subscale performance compared to the PANSS. The PSYRATS had good inter-rater and retest reliability. Validity was good, as assessed by internal consistency, sensitivity to change, and in relation to the PANSS. There was evidence of two delusion factors and three for hallucinations. The scales are useful complements to existing measures of symptom severity. © 2006 Elsevier B.V. All rights reserved. Keywords: First episode; Schizophrenia; Delusions; PSYRATS
1. Introduction Only a few structured assessments and interviews which assess dimensions of psychotic symptoms have been reported (e.g. Oulis et al., 1995; Wessely et al., 1993). Often little attention was paid to their psychometric properties and the investigations have mainly been focused on patients experiencing chronic psycho⁎ Corresponding author. Tel.: +44 161 291 5888; fax: +44 161 292 5882. E-mail addresses:
[email protected] (R. Drake),
[email protected] (G. Haddock),
[email protected] (N. Tarrier),
[email protected] (R. Bentall),
[email protected] (S. Lewis). 0920-9964/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2006.04.024
sis and little of this work has been done with recent onset psychosis. Watching the development of symptoms from first presentation is likely to be particularly informative since these symptoms are close to their origin and some will resolve never to return. The Psychotic Symptom Rating Scales (Haddock et al., 1999) are semi-structured interviews designed to assess the subjective characteristics of hallucinations and delusions (see Appendix). The auditory hallucinations subscale (AHS) has 11 items: for frequency, duration, controllability, loudness, location; severity and intensity of distress; amount and degree of negative content; beliefs about the origin of voices; and disruption. The delusions subscale (DS) has six items: duration and frequency of preoccupation; intensity of
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distress; amount of distressing content; conviction and disruption. The scales had excellent inter-rater reliability and good validity in sufferers from chronic schizophrenia (Haddock et al., 1999). The aim of the current study was to examine the psychometric properties of the PSYRATS in first episode, acutely psychotic patients.
affective psychoses and scored 4 or more on the PANSS hallucinations or delusions items. Nine were male and 4 female. The psychiatrists rated each of the 13 patients either simultaneously or on watching an interview video-taped by one of them. 3. Results
2. Method 3.1. Sample 2.1. Sample Patients were recruited from consecutive admissions to acute inpatient and day-patient facilities from geographically defined areas in the north of England over 26 months. They were recruited as part of a trial to assess the effectiveness of CBT for recent onset psychosis (Lewis et al., 2002; Tarrier et al., 2004). Inclusion criteria were: DSM-IV (APA, 1994) schizophreniform disorder, schizophrenia, schizoaffective disorder, delusional disorder or psychosis not otherwise specified; and age 16–65. Exclusion criteria were: organic brain disorder; psychosis purely due to substance use; and little fluency in English. A sub-sample, (see Section 3.1), was used to assess the retest reliability. 2.2. Procedure 2.2.1. Validity Patients were recruited and assessed within 14 working days of and re-interviewed 6 weeks later (Lewis et al., 2002) using the PANSS (Kay et al., 1989) and PSYRATS (Haddock et al., 1999) by three psychiatrists trained by GH and SL. The PANSS was chosen to assess validity of the PSYRATS even though the scales differ in structure and content. However, it was thought that the PANSS was the closest and most widely used scale with which to make comparisons to judge validity.
Two hundred fifty-seven first episode sufferers were recruited. One hundred nineteen (77%) were followed up at six weeks (Lewis et al., 2002). The first 103 first episode patients recruited to the study who had full PSYRATS data at five and six weeks were used in the test–retest analysis. Differences from the overall sample in demographics or symptoms were small and non-significant but fewer were substance dependent at baseline (10% compared to 17%, chi sq. p < 0.01). 3.2. Inter-rater reliability Average Intra-Class Correlations (ICCs; two way random effects models; Bartko and Carpenter, 1976) between raters for subscales and totals were excellent (DS 0.99 to 1.00, AH 0.99 to 1.00, total PSYRATS 0.99 to 1.00). ICCs for DS items ranged from 0.58 to 1.00, apart from ‘conviction in delusions' which had an ICC of 0.24. For AHS items ICCs ranged from 0.74 to 1.00 apart from ‘location of voices’ which had an ICC of 0.42 between 2 of the raters. Bland–Altman plots (Bland and Altman, 1986) were good for all pairings of raters on each subscale and the total: the largest discrepancy was 13% for 2 raters on the PSYRATS total. 3.3. Test–retest reliability
2.2.2. Test–retest reliability A sub-group of trial participants (see Section 3.1) were interviewed weekly for the first six weeks. PSYRATS scores for the 5th and 6th week interviews were compared to establish test–retest reliability, since symptoms between these points were relatively stable.
Data for weeks 5 and 6 were compared. ICCs were: DS 0.70; AH 0.70. Individual items had ICCs of 0.50 to 0.74 (DS items) and 0.55 to 0.74 (AH items) over the same period. This is despite changes in AH (median − 25%) and DS (median − 14%) over the time, presumably due to treatment.
2.2.3. Inter-rater reliability Thirteen patients were selected opportunistically and interviewed using the PANSS and PSYRATS. Four were from the main trial and nine other patients were attending for treatment at South Manchester University Hospitals NHS Trust. All met DSM IV criteria for non-
3.4. Internal consistency For the DS items, each correlated between 0.17 and 0.41 with the subscale score minus that item (Kendall's tau-b). For the AHS, each item correlated between 0.63 and 0.76 with the total minus that item (Kendall's tau-b)
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apart from ‘control over hallucinations’ (Kendall's tau-b 0.16). 3.5. Concurrent validity The DS significantly correlated (Spearman's) with the PANSS delusion item (0.43), positive subscale (0.20) and total score (0.18). The AH significantly correlated (Spearman's) with the PANSS hallucination item (0.81), positive subscale (0.31) and PANSS total (0.26). 3.6. Sensitivity to change in relation to the PANSS Sensitivity to change was examined in the DS and AH over the 6 weeks from inclusion in the trial. Again these resembled the overall sample at baseline (Lewis et al., 2002). For each parameter six-week change the score was calculated as: change divided by the baseline score minus the minimum possible score. Change in the DS significantly correlated (Spearman's) with the change in the PANSS delusions item (0.80), the positive subscale score (0.75) and in the PANSS total (0.69). Only the 124 patients experiencing auditory hallucinations at baseline were included in the AH analysis. Change in the AH significantly correlated (Spearman's) with change in the PANSS hallucination item (0.88), the positive subscale (0.63) and in PANSS total (0.54). 3.7. Structure of the subscales The DS and AHS at baseline were examined with SPSS 10.0 (SPSS, 2001) using factor analysis (Principal Axis Factoring, oblique rotation; Tabachnick and Fidell, 1996) and multi-dimensional scaling (MDS; Euclidean matrices, ALSCAL subroutine). The DS frequency, duration, conviction and disruption items loaded onto one factor and amount and intensity of distress onto another. The AHS distress and negative content items loaded onto one factor; frequency and duration onto a second; and belief about voices' reality, location, control and disruption onto a third. MDS of each subscale gave 2 dimensions as the most parsimonious solutions of acceptable fit (Everritt and Dunn, 2001). There were distinct groupings of items matching the factors found on PAF. 4. Discussion The inter-rater reliability of the PSYRATS subscales was very good but that of the items was less
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consistent, perhaps as the sample was small. The test– retest reliability was high despite the fact that the sample improved between the two time points assessed (probably due to their progression through treatment), deflating the correlations between item scores. The validation and scale item analysis used a large, relatively representative first admission sample, followed-up longitudinally with limited attrition. The PSYRATS was compared to the PANSS. Change scores for both PSYRATS subscales correlated well with those for corresponding PANSS items, suggesting that the PSYRATS assess psychotic symptoms validly. The AHS correlated particularly strongly at baseline with PANSS hallucinations. Both MDS and factor analysis were used to explore the structure of the PSYRATS subscales. MDS is a more valid method than factor analysis since the items are ordinal. However, although both produce similar results, the criteria for selecting solutions on PAF are better recognised and factor analysis enhances comparison with the smaller, chronic sample in Haddock et al. (1999). The factor structure observed in both samples was similar. The PSYRATS have good reliability and validity in first episode samples and complement existing measures of outcome like the PANSS. They offer a more detailed assessment of symptom dimensions, offering researchers and clinicians a better understanding of these key psychotic symptoms and their changes in response to treatment. Exploration of the structure of these symptoms will aid development of models of aetiology and intervention. Acknowledgements The authors acknowledge the work of the members of the SOCRATES team and the support of the Medical Research Council and Stanley Medical Research Institute (for Dr. Drake). We also thank Professor Graham Dunn for his assistance. Appendix A. The PSYRATS Scale detailed in Haddock et al. (1999). All items are scored 0–4, according to general criteria: 0 1 2 3 4
No problem Minimal or occasional Minor to moderate Major Maximum severity
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Each item is scored according to detailed anchor points, e.g.: Amount Of Preoccupation With Delusions. 0 No delusions, or delusions which the subject thinks about less than once a week 1 Subject thinks about beliefs at least once a week. 2 Subject thinks about beliefs at least once a day. 3 Subject thinks about beliefs at least once an hour. 4 Subject thinks about delusions continuously or almost continuously. Subject can only think about other things for a few seconds or minutes. Scale Items: Delusion Subscale Item Item Item Item Item Item
1: 2: 3: 4: 5: 6:
Amount Of Preoccupation With Delusions Duration of Preoccupation with Delusions Conviction Amount of Distress Intensity of Distress Disruption to Life Caused by Beliefs
Auditory Hallucinations Subscale Item 1: Item 2: Item 3: Item 4: Item 5: Item 6: Item 7: Item 8: Item 9: Item 10: Item 11:
Frequency Duration Location Loudness Beliefs Re Origin of Voices Amount of Negative Content of Voices Degree of Negative Content Amount of Distress Intensity of Distress Disruption to Life Caused by Voices Controllability of Voices
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