An Item Response Theory Analysis of the Psychosis Screening Questionnaire in Ethiopia.

AIM: Few psychosis screening instruments have been tested for use in Africa, yet appropriate tools can increase the detection of self-reported psychotic symptoms, improve the detection of psychosis and impact its prognosis. METHOD: The construct validity and factor structure of Psychosis Screening Questionnaire (PSQ) were tested with confirmatory factor analysis (CFA) and item response theory (IRT) in a sample of 1928 Ethiopian adults without any history of psychosis. We tested a unidimensional model with and without an item on mania. For IRT, unidimensional latent structure one-parameter logistic (1PL) and two-parameter (2PL) logistic models were tested and compared for relative fit using a likelihood-ratio test. RESULT AND DISCUSSION: The prevalence of lifetime positive screens was 2.8% in an Ethiopian sample of adults from a general medical setting. A unidimensional model demonstrated good fit for the PSQ, (CFI = 0.993, TLI = 0.986 and RMSEA = 0.025). For IRT, a 2PL model was the best fitting one. IRT tests of item difficulty and discrimination parameters showed that paranoia had the highest discrimination α = 4.59 $$ \left(\alpha =4.59\right) $$ and lowest difficulty ( ß = 2.53 $$ \beta =2.53 $$ ), likely to be endorsed at low levels of psychotic features. Thought insertion had the highest item difficulty ( ß = 2.98 $$ \beta =2.98 $$ ). Overall, the measure captures the psychosis construct at higher levels of the latent trait and may be suited for detecting moderate to severe levels of psychosis. CONCLUSION: The PSQ is found to have good construct validity in screening for psychosis among Ethiopian adults. Future studies may focus on the diagnostic validity of the PSQ comparing it with a structured clinical interview.

Psychometric properties and factor structure of the Kessler-10 among Ethiopian adults.

BACKGROUND: Many common mental disorders are underdiagnosed and undertreated in low-resource countries. The ten-item Kessler Psychological Distress Scale (K10) is a brief screening tool widely used to assess psychological distress. We evaluated the K10's performance in an Ethiopian population by assessing internal consistency and construct validity through factor structure. METHODS: K10 survey responses and sociodemographic data were collected from 1928 adults, including patients and caregivers from a general medical setting, who served as controls of a large epidemiological study. RESULTS: The K10 had good internal consistency, with a Cronbach's alpha of 0.83. Results from exploratory factor analyses showed that the K10 had a two-factor solution that accounted for approximately 66% of the variance. Confirmatory factor analyses demonstrated that a unidimensional model with correlated errors, informed by a theoretical model, was the best fitting model for the setting (comparative fit index of 0.90 and root mean square error of approximation of 0.10). LIMITATIONS: We did not assess the K10's test-retest reliability or its criterion validity (i.e., agreement with a reference measure). CONCLUSIONS: Based on internal consistency and construct validity, the K10 can effectively assess psychological distress among Ethiopian adults for population-based research and potentially clinical screening, consistent with previous findings in this setting. Further studies are needed to test its criterion validity against a reference measure of psychological distress.

Cross-country variations in the reporting of psychotic symptoms among sub-Saharan African adults: A psychometric evaluation of the Psychosis Screening Questionnaire.

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.

Measuring Traumatic Experiences in a Sample of Ethiopian Adults: Psychometric Properties of the Life Events Checklist-5.

Background: Traumatic events. e.g., road traffic accidents, violent conflicts, natural and human-made disasters, are common in sub-Saharan Africa. However, validated trauma screening tools to assess trauma at the individual level are lacking in many sub-Saharan African countries, such as Ethiopia, which limits accurate diagnosis and effective care provision. Objective: We sought to measure trauma exposure among cases and controls and evaluate the psychometric properties of the Life Event Checklist for DSM-5 (LEC-5) among Ethiopian adults. Method: This study included 4,183 participants (2,255 cases with a clinical diagnosis of psychosis and 1,928 controls without a history of psychosis) from the Neuropsychiatric Genetics of African Populations-Psychosis (NeuroGAP-Psychosis) study. We conducted exploratory factor analysis (EFA) to group the items into factors/subscales, and confirmatory factor analysis (CFA) to investigate the best model fit in Ethiopia. Result: 48.7% of participants reported exposure to at least one traumatic event. Physical assault (19.6%), sudden violent death (12.0%), and sudden accidental death (10.9%) were the three most common traumatic experiences. Cases were twice as likely to report experiences of traumatic events compared to controls (p<0.001). EFA revealed a four-factor/subscale model. CFA results indicated a theoretically-driven seven-factor model to be the preferred model by the goodness of fit (comparative fit index of 0.965 and Tucker-Lewis index of 0.951) and accuracy (root mean square error of approximation of 0.019). Conclusion: Exposure to traumatic events was common in Ethiopia, even more so for individuals with a diagnosis of psychotic disorders. The LEC-5 demonstrated good construct validity for measuring traumatic events among Ethiopian adults. Future studies that examine criterion validity and test-retest reliability of the LEC-5 in Ethiopia are warranted.