What's in a name? The MMPI-2 PTSD scales

Area of Science:

• Psychological assessment
• Clinical psychology
• Psychometrics

Background:

• The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) includes scales PK and PS intended to assess post-traumatic stress disorder (PTSD).
• Previous research has not definitively established the specific diagnostic utility of these MMPI-2 scales for PTSD.

Purpose of the Study:

• To examine the psychometric properties and diagnostic accuracy of the MMPI-2 post-traumatic stress disorder scales (PK and PS).
• To determine if PK and PS scales effectively differentiate between individuals with anxiety disorders and those with traffic accident-related conditions.

Main Methods:

• Correlational analyses were performed on MMPI-2 data from 96 outpatient anxiety disorder subjects and 97 outpatient traffic accident subjects.
• Principal components analyses were conducted to assess the variance contributed by PK and PS scales within each group.
• Discriminant function analyses were used to evaluate the classification accuracy of PK and PS scales.

Main Results:

• The PK and PS scales demonstrated a high correlation (.96) and highly similar patterns of correlation with other MMPI-2 scales across both groups.
• Principal components analyses indicated that PK and PS scales accounted for the most variance in the first component for both subject groups.
• Neither PK nor PS scales contributed significantly to the discriminant function classification of group members, despite group differences in overall MMPI-2 profiles.

Conclusions:

• The MMPI-2 PK and PS scales appear to function as indices of general emotional distress and maladjustment rather than specific PTSD indicators.
• The findings suggest limitations in using these scales for the direct diagnosis of post-traumatic stress disorder.
• Further research is needed to refine or identify more specific measures for PTSD assessment using the MMPI-2 or other instruments.