407: Physical Workload, Psychological Wellbeing, and Interacting Effects on Low Back Pain

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic primary musculoskeletal pain, Psychology, Developing methodology/technology, Pain in Special Populations

Background and Aims: Background
Low back pain (LBP) is the leading global cause of disability and is influenced by physical, psychological, and social factors (1–4). In working‑age adults, high physical workload, adverse psychological status, and social disadvantage are each linked to greater pain and poorer outcomes (5–8). However, most studies have treated these influences as separate or merely additive, rather than examining how they cluster and interact (9–11). There remains a need for population‑based analyses that model these multidimensional domains jointly and quantify their combined impact on LBP‑related outcomes in working‑age adults.

Aim of Investigation
We aim to quantify how the physical and psychological domains interact in predicting LBP-related outcomes in a large population-based representative sample of working-age people.

Methods: Methods:
Data in this study were from the North-West Adelaide Health Study, a 25-year cohort study based in the northern and western suburbs of Adelaide, South Australia. For 1,559 working-age adults from a survey follow-up stage in 2015, we applied exploratory factor analysis to demonstrate that physical workload could be represented as a latent construct characterized by twisting, bending, manual material handling and squatting at work, and psychological wellbeing can be represented a composite of overall mental wellbeing, depressive symptoms, and sleep disturbance. Subsequent structural equation modelling was then used to estimate the direct and interactive effects of these physical and psychological latent factors on the outcome, adjusting for body mass index (BMI) and additional covariates. The outcomes were related to LBP in the past 4 weeks, that is, no LBP, LBP without activity limitations, and LBP with activity limitations.

Results: Higher physical workload and poorer psychological status were independently associated with both LBP outcomes compared with no LBP. The largest effects were observed for LBP with activity limitations, and the interaction term indicated that poor psychological status strengthened the association between workload and disabling LBP. Higher BMI also increased the likelihood of pain, while financial strain mainly differentiated pain without limitations from no pain.

Conclusions: Physical workload and psychological status were each independently associated with higher odds of low back pain and together explained a meaningful proportion of variation in pain status. The SEM findings, including evidence of an interaction particularly for disabling pain, suggest that both domains, along with BMI and financial strain, are important targets for reducing low back pain and its associated limitations in working‑age adults.

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Presenting Author: Nasibeh Sorkhi Kojabad
Submitting Author: Nasibeh Sorkhi Kojabad

Senior Author: Tiffany Gill

IASP 2026 Global Year theme of Neuropathic Pain: No

• Nasibeh Sorkhi Kojabad: PhD Candidate - Adelaide University
• Tiffany Gill: PhD - Adelaide University
• Anastasia Ejova: PhD - Adelaide University