Socioeconomic status influences the relationship between fear-avoidance beliefs work and disability.

OBJECTIVE Biopsychosocial models are currently accepted for study of low back pain (LBP), but there is little evidence investigating socioeconomic status (SES) influence on disability, pain intensity, and physical impairment. The present study examined SES (income and education) and fear-avoidance model (fear-avoidance beliefs and pain catastrophizing) for their influence on disability, pain intensity and physical impairment. DESIGN Cohort study, where patients (n = 108) were referred to physical therapy for treatment of acute or sub-acute LBP and completed standard questionnaires. RESULTS SES had no statistically significant associations with disability, pain intensity, or physical impairment. Moderation analysis indicated that the interaction between fear-avoidance beliefs about work and SES accounted for significant amount of variance in disability scores (Beta = -0.24, t = -2.71, P = 0.008). The interaction indicated that people in the low SES group experienced a higher association of fear avoidance beliefs and disability at baseline, 4 weeks, and 6 months. Other moderation results between psychological factors and SES were not observed for pain intensity and physical impairment. CONCLUSIONS This study adds to the growing literature examining biopsychosocial models by considering SES. Our results suggest SES had a minimal influence on pain intensity and physical impairment, but did interact with fear-avoidance beliefs to influence disability.