Background: The PASS-20 is a general measure of pain-related anxiety and fear. The aim of the present study was to adapt the questionnaire for use in Spanish-speaking populations. Methods: Sample 1 comprised 216 individuals with chronic spinal pain (114 women and 102 men); sample 2 comprised 85 individuals with acute spinal pain (62 women and 23 men). The dimensionality of the PASS-20-SV items was evaluated using Exploratory Factor Analysis and an optimal implementation of Parallel Analysis (robust maximum likelihood). Data from sample 1 was used to analyse internal consistency and convergent validity. Estimated test-retest stability and predictive validity were based on data from the sample 2 participants, who completed the first administration (T1) and a second administration (T2, 6 months later). Results: The PASS-20-SV comprises two factors: pain-related anxiety and apprehension, and pain-related fear and avoidance. It has good to excellent reliability and adequate testretest stability. The results support its convergent and predictive validity. Conclusions: The Spanish Version of the PASS-20 is a valid, reliable measure of pain-related anxiety and pain-related fear in Spanish-speaking patients.
