Factor structure of psychosis screening questionnaire in Ugandan adults

Abstract

Abstract Background Psychotic disorders are common and contribute significantly to morbidity and mortality of people with psychiatric diseases. Therefore, early screening and detection may facilitate early intervention and reduce adverse outcomes. Screening tools that lay persons can administer are particularly beneficial in low resource settings. However, there is limited research evaluating the validity of psychosis screening instruments in Uganda. We aimed to assess the construct validity and psychometric properties of the Psychosis Screening Questionnaire (PSQ) in Uganda in a population with no history of a psychotic disorder. Methods The sample consisted of 2101 Ugandan adults participating as controls in a larger multi-country case-control study on psychiatric genetics who were recruited between February 2018 and March 2020. Participants were individuals seeking outpatient general medical care, caretakers of individuals seeking care, and staff or students recruited from five medical facilities that were age 18 years or older and able to provide consent. Individuals were excluded who had acute levels of alcohol or substance use, including being under inpatient hospitalization or acute medical care for one of these conditions. We used confirmatory factor analysis (CFA) and item response theory (IRT) to evaluate the factor structure and item properties of the PSQ. Results The overall prevalence screening positive for psychotic symptoms was 13.9% 95% CI (12.4,15.4). “Strange experiences” were the most endorsed symptoms 6.6% 95% CI (5.6,7.8). A unidimensional model seemed to be a good model or well-fitting based on fit indices including the root mean square error of approximation (RMSEA of 0.00), comparative fit index (CFI of 1.000), and Tucker-Lewis Index (TLI of 1.000). The most discriminating items along the latent construct of psychosis were items assessing thought disturbance followed by items assessing paranoia, with a parameter (discrimination) value of 2.53 and 2.40, respectively. Conclusion The PSQ works well in Uganda as an initial screening tool for moderate to high-level of psychotic symptoms.

Keywords

• Africa
• Psychosis screening questionnaire (PSQ)
• Psychometrics
• Construct validity
• Confirmatory Factor Analysis (CFA)
• Item response theory (IRT)