Mary Bitta1, Yanga Thungana2, Hannah H Kim3, Christy A Denckla4, Amantia Ametaj5, Mahlet Yared6, Claire Kwagala7, Linnet Ongeri8, Rocky E Stroud8, Edith Kwobah9, Karestan C Koenen4, Symon Kariuki10, Zukiswa Zingela2, Dickens Akena7, Charles Newton11, Lukoye Atwoli12, Solomon Teferra6, Dan J Stein13, Bizu Gelaye14. 1. Clinical Research-Neurosciences, KEMRI/Wellcome Trust Research Programme, Centre for Geographic Medicine Research (Coast), Kilifi, Kenya; Department of Psychiatry, University of Oxford, Oxford, UK. Electronic address: mbitta@kemri-wellcome.org. 2. Department of Psychiatry, Walter Sisulu University, Mthatha, South Africa. 3. Department of Social and Behavioral Sciences, Harvard T. H. Chan School of Public Health, Boston, MA, USA. 4. Department of Social and Behavioral Sciences, Harvard T. H. Chan School of Public Health, Boston, MA, USA; Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA; Stanley Center for Psychiatric Research at Broad Institute of MIT and Harvard, Cambridge, MA, USA. 5. Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA. 6. Department of Psychiatry, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia. 7. Department of Psychiatry, Makerere University, Kampala, Uganda. 8. Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA; Stanley Center for Psychiatric Research at Broad Institute of MIT and Harvard, Cambridge, MA, USA. 9. Department of Mental Health, Moi teaching and Referral Hospital, Eldoret, Kenya. 10. Clinical Research-Neurosciences, KEMRI/Wellcome Trust Research Programme, Centre for Geographic Medicine Research (Coast), Kilifi, Kenya. 11. Clinical Research-Neurosciences, KEMRI/Wellcome Trust Research Programme, Centre for Geographic Medicine Research (Coast), Kilifi, Kenya; Department of Psychiatry, University of Oxford, Oxford, UK. 12. Department of Mental Health, Moi teaching and Referral Hospital, Eldoret, Kenya; Medical College East Africa, The Aga Khan University, Nairobi, Kenya. 13. SA MRC Unit on Risk & Resilience in Mental Disorders, Dept of Psychiatry & Neuroscience Institute, University of Cape Town, Cape Town, South Africa. 14. Department of Social and Behavioral Sciences, Harvard T. H. Chan School of Public Health, Boston, MA, USA; Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA; Stanley Center for Psychiatric Research at Broad Institute of MIT and Harvard, Cambridge, MA, USA; The Chester M. Pierce, MD Division of Global Psychiatry, Massachusetts General Hospital, Boston, MA, USA.
Abstract
BACKGROUND: Self-reporting of psychotic symptoms varies significantly between cultures and ethnic groups. Yet, limited validated screening instruments are available to capture such differences in the African continent. METHODOLOGY: Among 9,059 individuals participating as controls in a multi-country case-control study of the genetic causes of psychosis, we evaluated the psychometric properties of the Psychosis Screening Questionnaire (PSQ). We applied multi-group confirmatory factor analysis and item response theory to assess item parameters. RESULTS: The overall positive endorsement of at least one item assessing psychotic symptoms on the PSQ was 9.7%, with variability among countries (Uganda 13.7%, South Africa 11%, Kenya 10.2%, and Ethiopia 2.8%). A unidimensional model demonstrated good fit for the PSQ (root mean square error of approximation = 0.009; comparative fit index = 0.997; and Tucker-Lewis Index = 0.995). Hypomania had the weakest association with single latent factor (standardized factor loading 0.62). Sequential multi-group confirmatory factor analysis demonstrated that PSQ items were measured in equivalent ways across the four countries. PSQ items gave more information at higher levels of psychosis, with hypomania giving the least discriminating information. LIMITATIONS: Participants were recruited from general medical facilities, so findings may not be generalizable to the general population. CONCLUSION: The PSQ demonstrated a unidimensional factor structure in these samples. Items were measured equivalently across all study settings, suggesting that differences in prevalence of psychotic symptoms between countries were less likely to represent measurement artifact. The PSQ is more reliable in screening for psychosis in individuals with higher degrees of psychotic experiences-hypomania excluded-and might decrease the false-positive rate from mild nonspecific psychotic experiences.
BACKGROUND: Self-reporting of psychotic symptoms varies significantly between cultures and ethnic groups. Yet, limited validated screening instruments are available to capture such differences in the African continent. METHODOLOGY: Among 9,059 individuals participating as controls in a multi-country case-control study of the genetic causes of psychosis, we evaluated the psychometric properties of the Psychosis Screening Questionnaire (PSQ). We applied multi-group confirmatory factor analysis and item response theory to assess item parameters. RESULTS: The overall positive endorsement of at least one item assessing psychotic symptoms on the PSQ was 9.7%, with variability among countries (Uganda 13.7%, South Africa 11%, Kenya 10.2%, and Ethiopia 2.8%). A unidimensional model demonstrated good fit for the PSQ (root mean square error of approximation = 0.009; comparative fit index = 0.997; and Tucker-Lewis Index = 0.995). Hypomania had the weakest association with single latent factor (standardized factor loading 0.62). Sequential multi-group confirmatory factor analysis demonstrated that PSQ items were measured in equivalent ways across the four countries. PSQ items gave more information at higher levels of psychosis, with hypomania giving the least discriminating information. LIMITATIONS: Participants were recruited from general medical facilities, so findings may not be generalizable to the general population. CONCLUSION: The PSQ demonstrated a unidimensional factor structure in these samples. Items were measured equivalently across all study settings, suggesting that differences in prevalence of psychotic symptoms between countries were less likely to represent measurement artifact. The PSQ is more reliable in screening for psychosis in individuals with higher degrees of psychotic experiences-hypomania excluded-and might decrease the false-positive rate from mild nonspecific psychotic experiences.
Authors: John J McGrath; Sukanta Saha; Ali Al-Hamzawi; Jordi Alonso; Evelyn J Bromet; Ronny Bruffaerts; José Miguel Caldas-de-Almeida; Wai Tat Chiu; Peter de Jonge; John Fayyad; Silvia Florescu; Oye Gureje; Josep Maria Haro; Chiyi Hu; Viviane Kovess-Masfety; Jean Pierre Lepine; Carmen C W Lim; Maria Elena Medina Mora; Fernando Navarro-Mateu; Susana Ochoa; Nancy Sampson; Kate Scott; Maria Carmen Viana; Ronald C Kessler Journal: JAMA Psychiatry Date: 2015-07 Impact factor: 21.596
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