Reliability and Validity of the Pain Anxiety Symptom Scale in Persian Speaking Chronic Low Back Pain Patients.

STUDY DESIGN: Psychometric testing of the Persian version of Pain Anxiety Symptom Scale 20.

OBJECTIVE: The aim of this study was to assess the reliability and construct validity of the PASS-20 in nonspecific chronic low back pain (LBP) patients.

SUMMARY OF BACKGROUND DATA: The PASS-20 is a self-report questionnaire that assesses pain-related anxiety. The Psychometric properties of this instrument have not been assessed in Persian-speaking chronic LBP patients.

METHODS: One hundred and sixty participants with chronic LBP completed the Persian version of PASS-20, Tampa Scale of Kinesiophobia (TSK), Fear-Avoidance Beliefs Questionnaire (FABQ), Pain Catastrophizing Scale (PCS), trait form of the State-Trait Anxiety (STAI-T), Oswestry Low Back Pain Disability Index (ODI), Beck Depression Inventory (BDI-II), and Visual Analogue Scale (VAS). To evaluate test-retest reliability, 60 patients filled out the PASS-20, 6 to 8 days after the first visit. Test-retest reliability (intraclass correlation coefficient [ICC], standard error of measurement [SEM], and minimal detectable change [MDC]), internal consistency, dimensionality, and construct validity were examined.

RESULTS: The ICCs of the PASS-20 subscales and total score ranged from 0.71 to 0.8. The SEMs for PASS-20 total score was 7.29 and for the subscales ranged from 2.43 to 2.98. The MDC for the total score was 20.14 and for the subscales ranged from 6.71 to 8.23. The Cronbach alpha values for the subscales and total score ranged from 0.70 to 0.91. Significant positive correlations were found between the PASS-20 total score and PCS, TSK, FABQ, ODI, BDI, STAI-T, and pain intensity.

CONCLUSION: The Persian version of the PASS-20 showed acceptable psychometric properties for the assessment of pain-related anxiety in Persian-speaking patients with chronic LBP.

LEVEL OF EVIDENCE: 3.