To cut a short test even shorter: Reliability and validity of a brief assessment of intellectual ability in Schizophrenia - A control-case family study

Eva Velthorst, Stephen Z. Levine, Cecile Henquet, Lieuwe De Haan, Jim Van Os, Inez Myin-Germeys, Abraham Reichenberg

Research output: Contribution to journalArticlepeer-review

Abstract

Background.The potential inclusion of cognitive assessments in the DSM-V and large time-consuming assessments drive a need for short tests of cognitive impairments. We examined the reliability and validity of a brief, 15-minute, version of the Wechsler Adult Intelligence Scale-III (WAIS-III).Methods.The sample consisted of patients diagnosed with schizophrenia (n=75), their siblings without schizophrenia (n=74) and unrelated healthy controls (n=84). A short WAIS-III consists of the Digit Symbol Coding subtest, and every second (or third) item of Block Design, Information, and Arithmetic. Psychometric analyses were implemented using item-response theory (IRT) to determine the best minimal item short version, while maintaining the sensitivity and reliability of the IQ score.Results.The proposed 15-minute WAIS-III gave reliable estimates of the Full Scale IQ (FSIQ) in all three groups in the sample. The 15-minute (select-item) version yielded an overall R of.95 (R2=.92) and IRT yielded an R of.96 (R2=.92). All four subtests performed well in differentiating patients, relatives, and healthy controls. Multivariate analysis showed a significant difference in FSIQ-estimate between patients, relatives, and healthy controls, F(2, 202) = 19.00, p <.0001. Regression modelling showed that the three versions of the WAIS had similar associations with functional outcome after a 3-year follow-up.Conclusions.Our proposed 15-minute version of the WAIS may serve as a useful screening device for general intellectual ability in research or clinical settings, and is recommended when a quick and accurate IQ estimate is desired.

Original languageEnglish
Pages (from-to)574-593
Number of pages20
JournalCognitive Neuropsychiatry
Volume18
Issue number6
DOIs
StatePublished - 1 Nov 2013

Bibliographical note

Funding Information:
EU-GEI is the acronym of the project ‘‘European network of National Schizophrenia Networks Studying Gene-Environment Interactions’’. The research leading to these results has received funding from the European Community’s Seventh Framework Programme under grant agreement No. HEALTH-F2-2010-241909 (Project EU-GEI).

Keywords

  • Cognitive functioning
  • Item response theory.
  • Psychometrics

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Cognitive Neuroscience

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