Assessing the psychometric properties of a supplementary PK Scale embedded in the Minnesota Multiphasic Personality Inventory -Adolescent (MMPI-A) in detecting post-traumatic stress disorder (PTSD)

This study explored the validity of the Minnesota Multiphasic Personality Inventory-Adolescent (MMPI-A; Butcher et al., 1992) PK Scale (Cashel, Ovaert and Holliman, 2000) to assess symptoms of Post-Traumatic Stress Disorder (PTSD) within an inpatient adolescent sample. The present research sought to expand upon the Cashel et al. (2000) study by assessing the predictive and comparative validity of the MMPI-A PK Scale. Information was gathered from the archival data of 631 adolescents who were referred to the assessment service of Four Winds Hospital. Adolescents were 13-18 years old and predominantly female (57.9%). The MMPI-A PK Scale significantly related to the following self-reported traumas measured by the Children\u27s Trauma Questionnaire (CTQ; Bernstein & Fink, 1998): emotional abuse (r = .31, p \u3c .01), sexual abuse (r = .14, p \u3c .01) and physical abuse (r = .08, p \u3c .05), respectively. Significant negative relationships between emotional neglect (r = .23, p \u3c .01) and physical neglect (r .09, p \u3c .05) were also found. The MMPI-A PK Scale significantly related to the Trauma Content Index (TC/R; Armstrong & Loewenstein, 1990), which was applied to Rorschach protocols (r = .14, p \u3c .01) scored using Exner\u27s Comprehensive System (CS; Exner, 2003). The relationships between the MMPI-A PK Scale and features associated with the presence of trauma, as measured by the Trauma Symptom Checklist for Children (TSCC; Briere, 1996), were explored. The MMPI-A PK Scale correlated highest with the Depression (DEP) clinical scale of the TSCC (r = .69, p \u3c .01). The relationship between the MMPI-A PK Scale and the Posttraumatic Stress (PTS) clinical scale of the TSCC (r = .59, p \u3c .01) was also significant and indicative of a moderate correlation. As a measure of PTSD symptoms, the MMPI-A PK Scale evidenced low to typical predictive validity (AUC = .696) when compared to the PTS scale. Other significant relationships between the MMPI-A PK Scale and the clinical scales of the TSCC were discussed. The MMPI-A PK Scale, as a diagnostic measure, performed similarly to the PTS scale. ROC analyses compared both the MMPI-A PK Scale and the PTS to discharge chart diagnosis. Both measures evidenced low to typical predictive validity (AUC = .613 and AUC = .621, respectively). The sensitivity and specificity of the MMPI-A PK Scale was also reviewed and compared to the sensitivity and specificity of the other measures. Implications, limitations and additional directions for future research were discussed