Changes in pain catastrophizing, fear-avoidance beliefs and pain self-efficacy mediate changes in disability in chronic low back pain

Key points

1. 01Pain catastrophizing uniquely mediated improvement in general disability (WSAS), explaining 33% of the total effect.
2. 02Fear-avoidance beliefs and pain self-efficacy each uniquely mediated improvement in self-reported physical functioning (PFS), together accounting for 72% of the total effect.
3. 03Pain self-efficacy alone mediated improvement in observed physical performance (BPS), explaining 74% of the total effect.
4. 04The direct effect of pain intensity on disability was absent once cognitive mediators were controlled, indicating cognitive factors drive functional gains.
5. 05Results suggest pain self-efficacy and fear-avoidance beliefs represent parallel but distinct pathways to improved physical functioning.

How it was conducted

Design

Secondary mediation analysis of data pooled from a 2-arm randomized controlled trial (fear-avoidance with in-session exposure vs. fear-avoidance without)

Participants

69 adults with chronic low back pain (localized L1-S1, duration more than 3 months, on sick leave), mean age approximately 43 years

Intervention

Group-based exposure treatment based on the fear-avoidance model, consisting of psychoeducation, cognitive restructuring, and homework assignments; weekly sessions plus a booster session at 9 weeks post-treatment

Mediators tested

Pain Catastrophizing Scale (PCS), Fear and Avoidance Beliefs Questionnaire (FABQ), Arthritis Self-Efficacy Scale (ASES, 3 items)

Disability outcomes

Work and Social Adjustment Scale (WSAS), Physical Functioning Scale from SF-36 (PFS), Back Performance Scale (BPS - observer-rated)

Analysis

Parallel mediation analysis using PROCESS macro (model 4), 95% CI with 10,000 bootstrap samples; change scores from pre-treatment to booster session

What they found

• For WSAS (general disability, n=69): PCS was the only significant unique mediator; indirect effect 0.37 (95% CI 0.07 to 0.82), ES 33%, standardized indirect effect 0.12. Direct effect of API on WSAS was 0.35 (95% CI -0.39 to 1.10), not significant.
• For PFS (self-reported physical functioning, n=69): FABQ indirect effect 0.20 (95% CI 0.01 to 0.47), ES 32%, standardized 0.11; ASES indirect effect 0.25 (95% CI 0.04 to 0.55), ES 40%, standardized 0.13; combined indirect effect 0.45 (ES 72% of total effect 0.63).
• For BPS (observed physical performance, n=61): ASES was the only significant unique mediator; indirect effect 0.17 (95% CI 0.01 to 0.36), ES 74%, standardized indirect effect 0.15.
• PCS was not a significant unique mediator for PFS (indirect effect 0.02, 95% CI -0.19 to 0.18, ES 3%) or BPS (indirect effect 0.00, 95% CI -0.08 to 0.08, ES 0%).
• No statistically significant between-group differences on change scores were found (ps 0.09-0.99) except for BPS where the FA condition outperformed FA-ISE.
• At pretreatment, mean pain intensity (API) was 3.9 (FA) and 3.8 (FA-ISE); at booster session, 2.8 (FA) and 3.7 (FA-ISE).

Limitations

• No control condition without active treatment, so causal inferences about the mediators cannot be firmly established.
• Small sample size (N=69 for most analyses, 61 for BPS) limits statistical power and generalizability.
• Treatment arms were pooled due to mostly non-significant between-group differences, which may obscure condition-specific mediation effects.
• Change scores measured pre-treatment to booster session only; temporal precedence of mediator change over outcome change was not established.

Why it matters

For patients

Reducing fear and worry about pain and building confidence in daily activities may matter more for regaining function than achieving pain relief alone.

For clinicians

Targeting pain catastrophizing, fear-avoidance beliefs, and self-efficacy should be monitored as indicators of treatment progress in exposure-based CLBP programs, with self-efficacy appearing particularly important for physical performance outcomes.

For readers

This study adds process-level evidence to the fear-avoidance model, showing distinct cognitive pathways to different disability outcomes, and highlights self-efficacy as a critical but sometimes overlooked treatment mechanism.