Table 1.

Summary of the data extraction from the nine included studies. Data within parentheses are CIs if not stated otherwise.

	Simony et al. (33)*	Grauers et al. (5)	Andersen et al. (6)*	Inoue et al. (32)	Kesling & Reinker (31)	Carr (30)	Fisher & DeGeorge (29)	Tang et al. (7)	Yang et al. (22)
Study type (twin/family)	Twin	Twin	Twin	Twin	Twin	Twin	Twin	Family	Family
Study size	21 pairs	526 pairsa	135 pairs	21 pairs	5 pairsb	6 pairs	14 pairs	1149 individuals	2732 individuals
Country of origin for study	Denmark	Sweden	Denmark	Japan	USA	UK	USA	HongKong	China
Scoliosis diagnosis	Radiographs	Self-assessment	Self-assessment	Radiographs	Radiographs	Radiographs	Radiographs	Radiographs	Radiographs
Zygosity determined by	DNA	Question-naire	Question-naire	DNA	Blood chemistry	DNA	Blood chemistry, clinical
Data on curve size available	Partly	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Concordance for monozygotic twins (pairwise)	0.40 (0.10 to 0.70)	0.11	0.13 (0.05 to 0.27)	0.92	0.50c	0.67	1.00d
Concordance for monozygotic twins (probandwise)	0.45 (0.16 to 0.74)	0.17	0.25 (0.17 to 0.37)	0.96c	0.33c	0.33c	0.50c, d
Concordance for dizygotic twins (pairwise)	0.05 (−0.05 to 0.15)	0.04	0.00 (0.00 to 0.03)	0.62	1.0c	0.0	0.57d
Concordance for dizygotic twins (probandwise)	0.10 (−0.03 to 0.23)	0.08	0.00	0.77c	0.5c	0.0c	0.36c, d
Tetrachoric correlations for monozygotic twins (dichotomous trait)		0.41 (0.33 to 0.49)
Tetrachoric correlations for dizygotic twins (dichotomous trait)		0.19 (0.09 to 0.29)
Correlations for monozygotic twins (continuous trait)				0.84 (0.53 to 0.95)			0.49 (−0.56 to 0.94)c
Correlations for dizygotic twins (continuous trait)				0.52 (−0.32 to 0.90)			−0.96 (−0.99 to −0.70)c
Broad sense heritability	0.70c	0.44c	0.13c	0.79c		0.67c	1.0c
Narrow sense heritability		0.38 (s.e.= 0.10)						0.88 (s.e. = 0.11)	0.49 (s.e. = 0.03)
Quality assessment	Good	Fair	Fair	Fair	Fair	Good	Good	Good	Fair

*These studies partly overlap; ^aAdditional cohort with 152 twin pairs with separately presented data. MZ pairwise concordance 0.08, DZ pairwise concordance 0; ^bFive pairs with available data; ^cCalculated data (see methods section); ^dConcordance rate calculated with 10 degree Cobb as threshold for affected.