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Original Research
Psychosis screening questionnaire: Exploring its factor structure among South African adults
Submitted: 06 February 2023 | Published: 17 November 2023
About the author(s)
Yanga A. Thungana, Department of Psychiatry, Faculty of Health, Walter Sisulu University, Mthatha, South AfricaZukiswa Zingela, Faculty of Health, Nelson Mandela University, Port Elizabeth, South Africa
Stefan J. Van Wyk, Department of Psychiatry, Faculty of Health, Walter Sisulu University, Mthatha, South Africa
Hannah H. Kim, Department of Social and Behavioral Sciences, Faculty of Public Health, Harvard T.H. Chan School of Public Health, Boston, United States
Amantia Ametaj, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, United States
Anne Stevenson, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, United States of America; Department of Psychiatry, Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, United States of America; and Department of Psychiatry, Faculty of Health Sciences, Stellenbosch University, Cape Town, South Africa
Rocky E. Stroud, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston; and Department of Psychiatry, Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, United States
Dan J. Stein, Department of Psychiatry and Mental Health, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
Bizu Gelaye, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston; Department of Psychiatry, Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge; and Division of Global Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, United States
Abstract
Background: Early detection of psychosis improves treatment outcomes, but there is limited research evaluating the validity of psychosis screening instruments, particularly in low-resourced countries.
Aim: This study aims to assess the construct validity and psychometric properties of the psychosis screening questionnaire (PSQ) in South Africa.
Setting: This study was conducted at several health centres in the Western and Eastern Cape provinces in South Africa.
Methods: The sample consisted of 2591 South African adults participating as controls in a multi-country case-control study of psychiatric genetics. Using confirmatory factor analysis and item response theory, we evaluated the psychometric properties of the PSQ.
Results: Approximately 11% of the participants endorsed at least one psychotic experience on the PSQ, and almost half of them (49%) occurred within the last 12 months. A unidimensional model demonstrated good fit (root mean square error of approximation [RMSEA] = 0.023, comparative fit index [CFI] = 0.977 and Tucker–Lewis Index [TLI] = 0.954). The mania item had the weakest association with a single latent factor (standardised factor loading = 0.14). Model fit improved after removing the mania item (RMSEA = 0.025, CFI = 0.991 and TLI = 0.972). With item response theory analysis, the PSQ provided more information at higher latent trait levels.
Conclusion: Consistent with prior literature, the PSQ demonstrated a unidimensional factor structure among South Africans. In our study, the PSQ in screening for psychosis performed better without the mania item, but future criterion validity studies are warranted.
Contribution: This study highlights that PSQ can be used to screen for early psychosis.
Keywords
Sustainable Development Goal
Metrics
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