Determinants of Between-Person Variation in Shoulder Pain in Individuals With Spinal Cord Injury: A Population-Based Cohort Study.

Objective: The aim of the study was to evaluate determinants of between-person variation in shoulder pain ("yes"/"no") in individuals with spinal cord injury living in Switzerland.

Design: This longitudinal study used data from the Swiss Spinal Cord Injury Cohort community surveys 2012, 2017, and 2022. Logistic regression analyses were used to identify determinants of between-person variability in shoulder pain while controlling for within-person variability.

Results: The prevalence of shoulder pain was 34.4% (95% CI = 33.0-35.9) when studying 4393 completed questionnaires. Significant determinants for between-subject variability revealed higher likelihoods for shoulder pain in females as compared with males (odds ratio: 1.57; 95% CI = 1.21-2.05), and when spasticity (1.49; 1.14-1.95), contractures (2.77; 2.21-3.48), and depression (1.39; 1.02-3.48) were present. In addition, shoulder pain presented highest likelihoods in individuals with incomplete tetraplegia (1.81; 1.32-2.48) versus incomplete paraplegia, in individuals over 26 yrs since injury (1.65; 1.15-2.37) versus up to 5 yrs since injury, and in individuals using a manual (2.17; 1.53-3.08) or electrical (2.16; 1.41-3.31) wheelchair versus no aids. There were significant interaction effects for gender with time since injury, contractures, and depression.

Conclusions: Determinants of between-subject variability in shoulder pain were female gender, lesion severity, time since injury, specific health conditions, and wheelchair use.