The structure of psychological distress

Area of Science:

• Psychological assessment
• Psychometrics
• Public health surveys

Background:

• The Psychological Distress Index (PDI) is used in the Quebec Health Survey.
• Assessing psychological distress is crucial for understanding population health.
• The PDI's factor structure and symptom inclusion require validation.

Purpose of the Study:

• To compare the factor structure of a 29-item PDI (including psychophysiological symptoms) with an 18-item version (cognitive and affective symptoms only).
• To evaluate the construct validity and associations with demographic and health indicators for both PDI versions.

Main Methods:

• Confirmatory factor analyses (LISREL VII) were performed on three samples (N=2,000).
• Logistic regression was used to assess associations with demographic variables and health indicators.
• The study focused on the factor structure of the Psychological Distress Index.

Main Results:

• Both the 18-item and 29-item versions of the PDI demonstrated satisfactory construct validity.
• Demographic associations were similar for both versions, except for age.
• The 29-item PDI showed a stronger association with health status indexes, indicating potential bias from somatic items.

Conclusions:

• The 29-item PDI, encompassing psychophysiological symptoms, offers a broader assessment but may introduce bias.
• The choice of PDI version depends on the research question and desired scope of distress measurement.
• Further research is needed to refine PDI's utility in diverse populations and health contexts.