Sleep disturbances as predictors of hospitalization for back disorders-a 28-year follow-up of industrial employees.

Study Design: A prospective cohort study.
Objective: To study the relationship of sleep disturbances with severe back disorders leading to hospitalization.
Summary of Background Data: Sleep disturbances are associated with persistent pain syndromes, but little is known about their relationship with back disorders.
Methods: The first hospital admission for back disorders from 1973 to 2000 was studied in a cohort of metal industry workers (n = 902). The occurrence of sleep disturbances at baseline was categorized as: none; 1 type (either difficulties in falling asleep/waking up at night or nightmares); or both types. Cox proportional hazards regression was used to estimate the time between the assessment of risk factors and first hospital admission for back disorders.
Results: Those individuals who had 1 type of sleep disturbance had a 2.1-fold (95% confidence interval 1.1-3.8) risk of back-related hospitalization, and those with both types of disturbance a 2.4-fold (1.2-4.6) risk, compared with those with no sleep disturbances. The hazard ratios were 2.1; 1.0-4.6 and 2.9; 1.2-7.1, respectively, when patients with chronic back disease or recurrent back symptoms at baseline were excluded from the analyses.
Conclusion: These findings suggest that sleep disturbances are predictive of hospitalization for back disorders. The mechanism underlying this association warrants further study.