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Validity of Simpson-Angus Scale (SAS) in a naturalistic schizophrenia population

Validity of Simpson-Angus Scale (SAS) in a naturalistic schizophrenia population

Authors :
Tuisku Katinka
Holi Matti M
Janno Sven
Wahlbeck Kristian
Source :
BMC Neurology, Vol 5, Iss 1, p 5 (2005)
Publication Year :
2005
Publisher :
BMC, 2005.

Abstract

Abstract Background Simpson-Angus Scale (SAS) is an established instrument for neuroleptic-induced parkinsonism (NIP), but its statistical properties have been studied insufficiently. Some shortcomings concerning its content have been suggested as well. According to a recent report, the widely used SAS mean score cut-off value 0.3 of for NIP detection may be too low. Our aim was to evaluate SAS against DSM-IV diagnostic criteria for NIP and objective motor assessment (actometry). Methods Ninety-nine chronic institutionalised schizophrenia patients were evaluated during the same interview by standardised actometric recording and SAS. The diagnosis of NIP was based on DSM-IV criteria. Internal consistency measured by Cronbach's α, convergence to actometry and the capacity for NIP case detection were assessed. Results Cronbach's α for the scale was 0.79. SAS discriminated between DSM-IV NIP and non-NIP patients. The actometric findings did not correlate with SAS. ROC-analysis yielded a good case detection power for SAS mean score. The optimal threshold value of SAS mean score was between 0.65 and 0.95, i.e. clearly higher than previously suggested threshold value. Conclusion We conclude that SAS seems a reliable and valid instrument. The previously commonly used cut-off mean score of 0.3 has been too low resulting in low specificity, and we suggest a new cut-off value of 0.65, whereby specificity could be doubled without loosing sensitivity.

Details

Language :
English
ISSN :
14712377
Volume :
5
Issue :
1
Database :
Directory of Open Access Journals
Journal :
BMC Neurology
Publication Type :
Academic Journal
Accession number :
edsdoj.b896bcc33b954cedb8f18b09f33e6542
Document Type :
article
Full Text :
https://doi.org/10.1186/1471-2377-5-5