Clinical Locomotion Science, University of Southern Denmark, Campusvej 55, 5230 Odense M, and Nordic Institute of Chiropractic and Clinical Biomechanics, Clinical Locomotion Science, Forskerparken 10A, 5230 Odense M, Denmark.
OBJECTIVE: To assess the relative contribution of genetic and environmental factors to different definitions of spinal pain and consequences of spinal pain. METHODS: The Danish Twin Registry contains detailed survey information on spinal pain and its consequences in twins ages 20-71 years. A classic genetic epidemiologic analysis was performed in order to establish heritability for a number of phenotypes, including location of pain, radiation of pain in the extremities or chest, pain duration, and combinations of pain in >1 spinal area. Consequences included reduced physical activity, sick leave, care seeking, change of work, and disability pension. The analysis included a biometric analysis based on the effect of shared genetic and common environmental factors. Furthermore, a bivariate twin model was fitted to identify genetic and environmental correlations. RESULTS: Altogether, data on 15,328 twin individuals (44% monozygotic and 56% dizygotic) from complete twin pairs were included. Genetic susceptibility explained approximately 38% of lumbar pain, 32% of thoracic pain, and 39% of neck pain. For patterns of pain, estimates were 7% for lumbar/thoracic, 24% for lumbar/cervical, 0% for thoracic/cervical, and 35% for pain in all 3 areas. Moderate to high genetic correlations indicated a common genetic basis for many spinal pain syndromes. In general, heritability was higher for women, and only a minor age effect was seen. CONCLUSION: Heritability estimates for pain in different spinal regions are quite similar and there is a moderate to high genetic correlation between the phenotypes. This may indicate a common genetic basis for a high proportion of spinal pain.