Parameter | LBP1^{*} | LSUM | LBP_1Q |
---|---|---|---|

σ_{AD}^{2} | 0.399±0.049, h^{2}=0.435^{†} | 28.315±2.665, h^{2}=0.682^{†} | 3.608±0.288, h^{2}=0.566^{†} |

σ_{RS}^{2} | 0.519±0.042 | 13.238±1.515 | 2.763±0.202 |

α_{0} | −0.0763±0.0282 | −18.056±2.224 | −0.8557±0.3754 |

β_{EXCERCISE} | – | NS | 0.6919±0.1337 |

β_{WEIGHT} | – | 0.0859±0.0203 | 0.0276±0.0054 |

β_{AGE} | – | 0.4831±0.0326 | – |

R_{AD} | 0.3662±0.0842 (p<0.001) | 0.3318±0.0705 (p<0.001) | |

R_{RS} | 0.0910±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; σ

_{AD}^{2}, σ_{RS}^{2}are variance components attributable to genetic and random environmental effects on each variable separately; α_{0}and β are regression parameters, intercept and slope for the corresponding significant covariates; R_{AD}and R_{RS}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.