Fatigue links sociodemographic risk to pain intensity and spread in 2 surgical cohorts

Why some surgical patients develop pain that extends beyond the original site of injury while others do not remains poorly understood. The recently proposed Risk of Pain Spread (ROPS) framework integrates multiple psychosocial risk factors associated with widespread pain, but its generalizability to surgical populations has not been established. Using 2 large presurgical cohorts of participants undergoing total knee arthroplasty or thoracic surgery, we evaluated the generalizability of the ROPS framework and examined relationships among psychosocial and sociodemographic factors, surgical-site pain, nonsurgical-site pain, and widespread pain using complementary latent-variable, regression, Bayesian network, and mediation analyses. Across cohorts and analytical approaches, fatigue emerged as the most consistent correlate of pain outcomes, independent of other measured risk factors. Fatigue also occupied a central position within the conditional dependency structure of psychosocial and pain variables and accounted for substantial shared variance linking sleep disturbance, depressive symptoms, neuroticism, adverse childhood experiences, and socioeconomic disadvantage with pain intensity. Nonsurgical-site pain consistently occupied a position linking pain intensity with widespread pain across complementary analyses. Together, these findings externally validate the ROPS framework in clinically relevant surgical populations and identify fatigue as a central correlate linking biopsychosocial vulnerability with pain burden.