Table 4

Sharing of genetic and environmental parameters between LDD and LBP: bivariate variance component analysis

σAD20.399±0.049, h2=0.43528.315±2.665, h2=0.6823.608±0.288, h2=0.566
 RAD0.3662±0.0842 (p<0.001)0.3318±0.0705 (p<0.001)
 RRS0.0910±0.080 (p=0.29)0.0815±0.0786 (p=0.41)
  • * LBP1 variable was adjusted using parameter estimates in multiple logistic regression (table 3), in which the contribution of the low back pain (LBP) status of twins was not included; Parameter estimates ± standard errors of estimates are provided in the table.

  • Contribution of the putative genetic effects (heritability estimate), adjusted for all significant covariates; σAD2, σRS2 are variance components attributable to genetic and random environmental effects on each variable separately; α0 and β are regression parameters, intercept and slope for the corresponding significant covariates; RAD and RRS are genetic and environmental correlations between LSUM and each of the two LBP variables respectively; p value in comparison with the corresponding general model in which all model parameters were estimated.

  • LDD, lumbar disc degeneration; LSUM, summary rank for four LDD traits.