Factor Structure of the Pain Disability Index in Workers’ Compensation Claimants With Low Back Injuries

Abstract 

Tait RC, Chibnall JT. Factor structure of the Pain Disability Index in workers’ compensation claimants with low back injuries. Arch Phys Med Rehabil 2005;86:1141–6.

Objective

To examine the factor structure of a telephone-administered Pain Disability Index (PDI) and the effects of race and sex on the PDI.

Design

Computer-assisted telephone interviews of a cohort with occupational low back injuries.

Setting

General community.

Participants

Missouri workers’ compensation claimants (N=1329) with low back injuries.

Interventions

Not applicable.

Main Outcome Measures

PDI, levels of pain severity, Social Security Disability Insurance status, and the Fear-Avoidance Behavior Questionnaire.

Results

Results for the total sample and by race/sex group indicated support for a 2-factor model of the PDI corresponding to voluntary activities (eg, social, occupational, recreational) and obligatory activities (eg, activities of daily living, eating, sleeping). Additional psychometric analyses of the voluntary and obligatory subscales indicated adequate reliability and construct validity overall and in each of the race/sex groups. African Americans reported more pain-related disability on both subscales than whites. Women reported more disability on the voluntary subscale than men.

Conclusions

The results support use of the PDI as a bidimensional measure of pain-related disability, with strong psychometric properties. They also support its administration by telephone.

Key Words:  Disability evaluation , Low back pain , Occupational medicine , Rehabilitation , Workers’ compensation