The creation and validation of the Jamaica Personality Disorder Inventory

To describe the creation and validation of the Jamaica Personality Disorder Inventory (JPDI) screening questionnaire. Using the phenomenological triad of power management, dependency and psychosexual issues, drafts of the JPDI were piloted on patients from psychiatric and medical wards. The JPDI consisted of 38 close-ended, yes/no questions. Validation was conducted in a sample of 200 patients, using the International Personality Disorder Examination-Screening Instrument (IPDE-S), the Brief Screen for Depression and consultant psychiatrists' Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) personality disorder interview. Construct validity was assessed through principal component factor analysis; Spearman correlation was used to assess criterion-related and discriminant validity; Cronbach's alpha was used to assess reliability of the entire scale as well as the resulting factors. The Multitrait Multimethod Matrix (MTMM) was used to assess discriminant and construct validity. Factor analysis revealed eight clusters consisting of 30 of the 38 questions, which had close congruence with the clinical triad. Cronbach's alpha for the entire scale was α = 0.79, ranging from a high 0.70 to 0.82 to low 0.63 to 0.45. The JPDI exhibited a sensitivity of 95.06% and a specificity of 67.71%. Significant correlation of scores for the JPDI and IPDE-S (r = 0.432, p = 0.000) and the JPDI and the DSM IV-TR diagnosis (r = 0.598, p = 0.000) established concurrent validity for the JPDI. Correlations (r = 0.293, p = 0.000) suggested that the JPDI possessed predictive validity. The complete sample matrix of the MTMM provided evidence of both convergent and discriminant validity, and thereby, construct validity. The JPDI demonstrated reliability, and criterion-related and discriminant validity.