Soc Psychiatry Psychiatr Epidemiol (2007) 42:819–823
DOI 10.1007/s00127-007-0249-1
ORIGINAL PAPER
Yvette Kusel Æ Richard Laugharne Æ Sian Perrington Æ Jan McKendrick Æ Deborah Stephenson J. Stockton-Henderson Æ Madeline Barley Æ R. McCaul Æ Tom Burns
Measurement of quality of life in schizophrenia: a comparison of two scales
Received: 26 October 2006 / Accepted: 31 July 2007 / Published online: 29 August 2007
j Abstract Background People with schizophrenia have an impaired quality of life (QoL), and various QoL assessment scales are available. However it is not clear which scale should be used in different situations. We aimed to compare a patient-rated subjective QoL scale with an observer-rated QoL scale by measuring their degree of correlation and their respective associative profiles with outcome measures. Method Patients of the UK Schizophrenia Care and Assessment Program completed a patient-rated QoL ques-
Y. Kusel St. Charles Hospital London, UK Dr. R. Laugharne (&) Cornwall Partnership Trust and Mental Health Research Group Peninsula Medical School Wonford House Hospital Exeter EX2 5AD, UK Tel.: +44-1392/403-462 Fax: +44-1392/4034-21 E-Mail:
[email protected] S. Perrington Quintiles (UK) Ltd. Bracknell (Berks), UK J. McKendrick Æ D. Stephenson Eli Lilly & Co. Ltd. Basingstoke, UK J. Stockton-Henderson Crichton Royal Hospital Dumfries, UK M. Barley University of Bristol Bristol, UK R. McCaul Queen’s University Belfast, UK
j Key words quality of life – schizophrenia
Introduction Schizophrenia can often be a chronic and debilitating mental illness, producing deficits in clinical, psychosocial and economic functioning. The full impact of schizophrenia is therefore hard to assess without information from these disparate sources. Quality of life (QoL) scales have become increasingly used as outcome measures for schizophrenia, since they are designed to assess this diverse database. Indeed, Sartorious [1] proposed that QoL should be a central concern in the rehabilitation of people with severe and persistent mental illness. There is no one accepted definition of QoL, similarly there are a wide variety of QoL assessment tools [2, 3]. Some of these tools are patient-rated, whilst others are observer-rated (where the observer is often a clinician or trained researcher). Previous
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T. Burns Department of Social Psychiatry University of Oxford Oxford, UK
tionnaire (MANSA). Research staff completed the observer-rated QoL tool (QLS) as part of an assessment of symptomatology and functioning. Results The two QoL tools were moderately positively correlated (r = 0.39). Both scales were negatively correlated with positive and negative symptoms of schizophrenia and depressive symptoms, and positively correlated with functioning scores. However the two scales were influenced by different factors. The patient-rated QoL was more significantly influenced by depressive symptoms, and the observer-rated QoL was more heavily influenced by negative symptoms. Conclusions Patient-rated and observer-rated QoL are moderately related, with a number of joint determinants, but the former is sensitive to depressive influences, whilst the latter is sensitive to the negative symptomatology of schizophrenia.
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studies have found a variety of strengths of relationship between patient- and observer-rated QoL tools [4, 5]. Patient-rated QoL scales have been advocated as representing factors that matter most to the patient. However, the validity of patient-rated QoL in schizophrenia has been questioned on the grounds that disorganised thinking, lack of insight, and changes in mood may influence such subjective QoL assessments [6]. The aim of the current study was to investigate the relationship between two patient and observer-rated QoL tools in people with schizophrenia. The study was designed to examine both the relatedness of these two measures, and their respective associations with concurrent measures of clinical and social functioning.
Material and methods
j Other assessment tools UK-SCAP utilised a large battery of assessment tools including: the Positive and Negative Syndrome Scale (PANSS) [13], the Montgomery-Asberg Depression Rating Scale (MADRS) [14], the Abnormal Involuntary Movement Scale (AIMS) [15], the SimpsonAngus Scale (SA) [16], the Barnes Akathisia Scale [17], and the Global Assessment of Functioning (GAF) [8]. In addition, at each six-monthly interview, the SCAP instrument was completed; this was a 100-item instrument, which was designed to measure a broad range of outcome variables. A number of these outcome variables were selected to be included in the analyses reported in this paper, including: general health status, housing status, occupational status, financial status, social contact, family contact and personal relationships. j Statistical analyses A Pearson product moment correlation coefficient was calculated to investigate the relationship between MANSA and QLS. Additional correlation and regression analyses were carried out for both QoL tools, in order to investigate the various outcome factors that were associated with each of the QoL assessments.
j Subjects
j Ethics
The study was part of UK-SCAP- a prospective, observational study of 601 patients with schizophrenia who were recruited from six sites within the UK [7]. The study lasted for a period of 2 years, with interviews occurring every 6 months. It was part of a larger study that was also undertaken within the United States of America (US-SCAP) and Australia (AUS-SCAP). The subjects for this study were 442 patients who were seen for the 18-month interview in UK-SCAP. Subjects were recruited from both inpatient and outpatient settings. Inclusion criteria for UKSCAP included: fulfilling the criteria for schizophrenia, schizoaffective disorder, or schizophreniform disorder as defined in the DSM-IV [8], 18 years of age or older, sufficient ability to communicate with the researchers in simple spoken and written English, ability to understand the nature of the study and competence to sign an informed consent form. The exclusion criteria were: involvement in controlled clinical drug trials within the 30 days prior to entry to the study, and likelihood of not being available for follow-up.
Subjects signed an informed consent from prior to entry to the study. Both the local research ethics committee, and the multiresearch ethics committee approved the informed consent form. Subjects were free to withdraw consent to the study at any time.
j Assessment of QoL Quality of Life Scale (QLS) [9] This is a 21 item scale, each scored on a seven-point interval scale. The QLS is widely used with patients with schizophrenia, and is suitable for community-based patients. Subjects were rated throughout the 2 years of UK-SCAP every six months. This observer-rated QoL tool involves a semi-structured interview by a trained researcher, which focuses on symptoms and functioning within the last month.
Results The SCAP study recruited 601 patients suffering from schizophrenia or schizoaffective disorder. A total of 442 (73.5%) completed the fourth interview. Of the patients missing for this interview, 72 (12.0%) had withdrawn from the study, 49 (8.2%) missed that visit and 38 (6.3%) were hospitalised and could not be interviewed. Of the 442 seen, 410 completed the QLS, 400 completed the MANSA and 394 both questionnaires. Patients were generally able to complete the MANSA with little or no assistance from the researchers which is inconsistent with one previous study [18]. The descriptive statistics for the QLS and the subjective questions of the MANSA are given in Table 1. Whilst 394 patients had both questionnaires completed, 26 completed neither, 16 only the QLS and six only the MANSA. The patients who completed Table 1 Summary statistics of the MANSA and QLS scores
Manchester Short Assessment of Quality of Life (MANSA) [10] The third section contains all the QoL items- 12 satisfaction ratings, scored on a seven-point interval scale, and four objective Yes/No questions. This patient-rated scale has been developed from the original Quality of Life Interview [11] and its follow-up, the Lancashire Quality of Life Profile [12]. Given the large amount of data that was already being recorded within UK-SCAP, only the third section of the MANSA needed to be administered. This was collected at the 18-month interview.
Mean SD Median Mode Range Kurtosis No. of patients
MANSA
QLS
4.58 0.77 4.67 4.25 2.00–7.00 0.29 400
3.02 1.04 2.90 2.89 0.76–5.83 )0.28 410
821 Table 2 Correlation of QOL scales with clinical outcome scales
PANSS total PANSS positive symptoms PANSS negative symptoms MADRS GAF S GAF F
Table 3 MANSA regression analysis data
MANSA
QLS
)0.37 )0.26 )0.25 )0.56 0.39 0.36
)0.57 )0.30 )0.64 )0.40 0.48 0.70
Depressive symptoms Global functioning General health Financial status Social contact Family contact Personal relationship
Scale
F Value
Significance
MADRS GAF SF12 SCAP questionnaire SCAP questionnaire SCAP questionnaire SCAP questionnaire
44.2 9.4 6.9 32.3 43.5 40.3 4.6
