Abstract / Summary
Chronic pain is common among people with opioid use disorder (OUD), yet pain-related disability, the degree to which pain restricts functioning and participation in daily life, has received little empirical attention as a primary OUD outcome. Drawing on Critical Disability Studies (CDS), Structural Vulnerability Theory, and the biopsychosocial model of pain, this thesis examines the structural, psychosocial, and health-related correlates of self-identified pain-related disability among current and former injectable opioid agonist treatment (iOAT) clients in British Columbia, Canada. This cross-sectional secondary analysis used baseline data from PORTIA, a longitudinal cohort study conducted in British Columbia's Lower Mainland between 2022 and 2024 (N = 139). Self-identified disability (excluding substance use disorder) was categorized as no disability, non-pain-related disability, or pain-related disability, consistent with the Accessible Canada Act definition of disability. Firth's bias-reduced logistic regression examined structural, psychosocial, and healthcare-related predictors using a domain-by-domain approach. Approximately half of participants (49.6%) reported pain-related disability. Two independent associations emerged. Consistent food access was independently associated with significantly lower odds of both pain-related (OR = 0.22, 95% CI: 0.05–0.92) and non-pain-related disability (OR = 0.20, 95% CI: 0.05–0.88) relative to no disability, suggesting that material deprivation is associated with disability regardless of type. Reduced physical functioning was specifically associated with pain-related disability (OR = 0.92 per point, 95% CI: 0.88–0.96), supporting the biopsychosocial model's proposition that pain-related disability is grounded in measurable physical impairment. Psychosocial variables were not independently associated with disability status. Although 42% of participants met probable PTSD criteria, this high prevalence did not vary across disability groups, reflecting a pervasive structural background condition rather than a differentiating factor. Among participants with disability (n = 115), disability discrimination was independently associated with lower odds of pain-related versus non-pain-related disability (OR = 0.36, 95% CI: 0.16–0.82), indicating that discrimination was more common among those with non-pain-related disability, aligning with CDS accounts of how social legibility shapes ableist exposure. These findings highlight material deprivation and embodied structural disadvantage as key contributors to pain-related disability among people with severe OUD and support integrating food security assessment and physical rehabilitation into iOAT care.