Table 2.

Heritability of Kyphosis Angle and Other Spine Traits and Phenotypic, Genetic, and Environmental Correlations Between Kyphosis Angle and Other Spine Traits

		Heritability		Adjusted correlations between kyphosis angle and other spine traitsa
	n	Crude h2 (95% CI)	Adjusted h2 (95% CI)a	${\widehat{\rho }}_{\mathrm{P}}$ (95% CI)	p	${\widehat{\rho }}_G$ (95% CI)	p	${\widehat{\rho }}_{\mathrm{E}}$ (95% CI)	p
Kyphosis angle (degrees)	2063	0.41 (0.30 to 0.51)b	0.54 (0.43 to 0.64)b	—	—	—	—	—	—
Vertebral fracture (summary index)	1192	0.39 (0.22 to 0.57)b	0.41 (0.23 to 0.59)b	0.27 (0.21 to 0.32)	<0.01	0.39 (0.18 to 0.61)	<0.01	0.15 (−0.04 to 0.34)	0.13
Disc height narrowing (summary index)	1191	0.49 (0.32 to 0.67)b	0.49 (0.31 to 0.66)b	0.15 (0.10 to 0.21)	<0.01	0.17 (−0.05 to 0.38)	0.14	0.14 (−0.07 to 0.35)	0.19
Facet joint OA (summary index)	1191	0.56 (0.40 to 0.72)b	0.63 (0.47 to 0.79)b	0.14 (0.09 to 0.20)	<0.01	0.05 (−0.15 to 0.24)	0.64	0.28 (0.05 to 0.51)	0.02
L3 vBMD (g/cm3)	2002	0.19 (0.08 to 0.29)b	0.40 (0.28 to 0.52)b	−0.07 (−0.12 to −0.03)	<0.01	−0.23 (−0.41 to −0.04)	0.02	0.06 (−0.09 to 0.21)	0.41
T7/T8 paraspinal muscle area (mm2)	1123	0.37 (0.17 to 0.58)b	0.54 (0.32 to 0.75)b	−0.28 (−0.33 to −0.22)	<0.01	−0.46 (−0.67 to −0.26)	<0.01	−0.07 (−0.29 to 0.14)	0.51
T7/T8 paraspinal muscle density (HU)	1123	0.32 (0.11 to 0.52)b	0.35 (0.16 to 0.55)b	−0.19 (−0.24 to −0.13)	<0.01	−0.22 (−0.48 to 0.03)	0.10	−0.16 (−0.35 to 0.03)	0.11

^aAdjusted for age, sex, and weight. Bivariate models were used to estimate genetic correlations (ρ_G) and environmental correlations (ρ_E) between kyphosis angle and each spine trait based on ${\mathrm{\rho }}_{\mathrm{P}}={\mathrm{\rho }}_{\mathrm{G}}\sqrt{{{\mathrm{h}}_1}^2{{\mathrm{h}}_2}^2}+{\mathrm{\rho }}_{\mathrm{E}}\sqrt{\left(1-{{\mathrm{h}}_1}^2\right)\left(1-{{\mathrm{h}}_2}^2\right)}$ where (ρ_P) is the phenotypic correlation between traits, and h₁² and h₂² are the heritability estimates for trait 1 and trait 2, respectively.⁽⁴¹⁾

^bp < 0.001.