Insomnia severity and its impact on health-related quality of life and pain in individuals diagnosed with persistent spinal pain: A prospective cohort study

BACKGROUND: Insomnia is prevalent among individuals with persistent spinal pain and may exacerbate symptom burden. However, current evidence is limited by heterogeneity in study design and low certainty, and the magnitude and temporal stability of associations with patient-reported outcomes remain insufficiently understood. Moreover, it is unclear whether clinically applicable instruments can distinguish patient subgroups with differing symptom trajectories and burden. METHODS: This prospective cohort study investigated associations between insomnia severity (Insomnia Severity Index) and health-related quality of life (EQ-5D-5L Index), pain intensity, and pain-related disability (Brief Pain Inventory) in individuals with persistent spinal pain. Participants were followed for 12 months with assessments at baseline, 3, 6, and 12 months. Mixed-effects models estimated differences across insomnia severity levels and tested interaction with time. RESULTS: Higher insomnia severity was associated with lower health-related quality of life and higher pain intensity and disability over time, with differences exceeding thresholds for clinical relevance. Compared with no insomnia, severe insomnia was associated with -0.25 lower EQ-5D-5L (95% CI -0.31 to -0.20), higher pain intensity (2.49, 95% CI 1.89 to 3.08), and greater disability (physical: 2.79, 95% CI 2.10 to 3.48; affective: 4.43, 95% CI 3.75 to 5.10). No evidence of effect modification by time was observed. CONCLUSION: Among individuals with persistent spinal pain, insomnia severity is consistently associated with worse patient-reported outcomes over 12 months, underscoring its clinical relevance. These findings support addressing sleep disturbances within integrated and individualized management of persistent spinal pain and suggest potential value for risk stratification and symptom profiling.