Does the heritability of chronic low back pain depend on how the condition is assessed?

Background Although the influence of genetics on chronic low back pain (LBP) has been previously examined, few studies have investigated whether the impact of genetic factors on LBP depends on how the condition is assessed. Methods We investigated the contribution of genetics and environment on chronic LBP: lifetime prevalence, pain intensity (recent and worst) and activity limitation (anytime and recent) in a cross-sectional study with 1,598 adult twins. All twins answered a self-reported questionnaire about health-related questions. We conducted classic twin analyses using structural equation models to estimate the genetic and environmental influences in LBP phenotypes. Results We found a heritability of 26% (95%CI: 0.09-0.42) for lifetime chronic LBP; 36% (95%CI: 0.18-0.52) and 25% (95%CI: 0.03-0.46) for activity limitation due to chronic LBP, related to lifetime and most recent episode, respectively; and heritability of 35% (95%CI: 0.11-0.55) for pain intensity associated with the most recent episode. Genetics showed no significant influence in pain intensity experienced during the worst LBP episode. Conclusions Genetic factors appear to significantly contribute to the variance in chronic LBP including lifetime chronic LBP, activity limitation and pain intensity associated with more recent episodes of LBP, but not for pain intensity associated with people's report of the worst pain episode. Heritability estimates was fairly similar across different LBP outcomes in a population-based twin sample, and not dependent on how it is assessed or experienced. However, we could not detect any significant heritability for a report of intensity experienced during the worst LBP episode experienced. Significance Heritability estimates were similar for different low back pain definitions, and therefore not dependent on how chronic low back pain is experienced or assessed, in the same population-based sample.