Heritability of neck pain: a population-based study of 33 794 Danish twins

Objectives. To determine the heritability of neck pain in a large population-based study of twins. Methods. Data on lifetime prevalence of neck pain from a population-based cross-sectional survey of Danish twins were used. To assess twin similarity, the probandwise concordance rates, zygosity-specific odds ratios and tetrachoric correlations were calculated and compared for monozygotic and dizygotic twins. Using biometric modelling (structural equation modelling), the genetic and environmental contributions of the liability to neck pain were estimated. Results. A total of 33 794 twins (response rate 73%) answered the questions regarding neck pain. Probandwise concordance rates, zygosity-specific odds ratios and tetrachoric correlations showed a significant genetic effect on neck pain. An overall additive genetic component of 44% was found. The genetic effect decreased with age, accounting for only 10% in the oldest male group and 0% in the oldest female group. There was a statistically significant difference in heritability between males and females (34 vs 52%, P < 0.0001). Conclusions. Genes play a significant role in neck pain, particularly in women. However, the genetic influence becomes gradually less important with increasing age, and environmental factors dominate almost completely in the older age groups.