Small Effect of Genetic Factors on Neck Pain in Old Age

In Brief Study Design. Classic twin study. Objectives. To determine the heritability of neck pain in persons 70 years of age and older. Summary of Background Data. Previous studies have shown a moderate effect of genetic factors on back pain in the elderly. Genetic influence on neck pain in old age is unknown. Methods. Data on the 1-month prevalence of neck pain from twin pairs participating in the population based Longitudinal Study of Aging Danish Twins formed the basis of this analysis. To assess twin similarity, probandwise concordance rates, odds ratios, and tetrachoric correlations were calculated and compared for monozygotic and dizygotic twins. Further, heritability estimates were calculated using bivariate probit estimation. Results. A total of 2,108 twin individuals, including 1,054 complete twin pairs, answered the question related to neck pain at intake into the Longitudinal Study of Aging Danish Twins study. Low and nonsignificant probandwise concordance rates, odds ratios, and tetrachoric correlations were found for both men and women in monozygotic and dizygotic twin pairs, indicating small or negligible genetic effects. Heritability estimates adjusted for age and significant environmental risk factors (rheumatoid arthritis, osteoarthritis, disc prolapse, and coronary heart disease) showed no significant additive genetic, dominant genetic, or common environmental effects. Conclusion. Genetic factors do not play an important role in the liability to neck pain in persons 70 years of age or older. The relative contribution of genetic and environmental factors in the liability to neck pain in old age was assessed in a population-based sample of Danish twins 70 years of age and older. Genes were found to play a minor role in both men and women, and practically all of the variation in the liability to neck pain occurrence in old age can be explained by the additive effect of individual environmental factors.