Table 2.

Age-standardised and gender-standardised prevalence of mild SCH, severe SCH and OH in the general Chinese adult population

	Prevalence % of mild SCH (95% CI)			Prevalence % of severe SCH (95% CI)				Prevalence % of OH (95% CI)
	Men	Women	Total	Men	Women	Total	Men	Women	Total
N	3964	6399	10 363	274	472	746	226	715	941
Prevalence	9.30 (8.57 to 10.09)	15.12 (14.03 to 16.27)	12.18 (11.31 to 13.10)	0.56 (0.43 to 0.74)	0.94 (0.82 to 1.08)	0.75 (0.65 to 0.87)	0.53 (0.41 to 0.67)	1.53 (1.33 to 1.75)	1.02 (0.88 to 1.18)
Age
18–29	8.74 (7.81 to 9.76)	13.58 (12.14 to 15.17)	11.14 (10.23 to 12.11)	0.59 (0.26 to 1.34)	0.67 (0.51 to 0.89)	0.63 (0.41 to 0.97)	0.13 (0.06 to 0.31)	0.77 (0.41 to 1.44)	0.45 (0.25 to 0.80)
30–39	7.08 (6.34 to 7.89)	12.22 (11.24 to 13.27)	9.59 (8.82 to 10.43)	0.36 (0.21 to 0.61)	0.66 (0.52 to 0.84)	0.50 (0.39 to 0.66)	0.31 (0.19 to 0.50)	1.11 (0.84 to 1.48)	0.70 (0.55 to 0.89)
40–49	8.32 (7.28 to 9.49)	14.67 (12.76 to 16.81)	11.43 (10.06 to 12.96)	0.29 (0.21 to 0.40)	0.94 (0.72 to 1.24)	0.61 (0.48 to 0.78)	0.51 (0.39 to 0.67)	2.05 (1.64 to 2.55)	1.26 (1.04 to 1.53)
50–59	10.15 (9.05 to 11.37)	17.87 (15.93 to 19.98)	13.94 (12.67 to 15.43)	0.82 (0.56 to 1.21)	1.31 (0.99 to 1.73)	1.06 (0.83 to 1.36)	0.71 (0.41 to 1.23)	1.93 (1.52 to 2.44)	1.31 (1.00 to 1.72)
≥60	13.54 (11.84 to 15.45)	18.94 (16.96 to 21.10)	16.30 (14.58 to 18.17)	0.90 (0.63 to 1.29)	1.35 (1.05 to 1.75)	1.13 (0.88 to 1.45)	1.28 (0.99 to 1.64)	2.12 (1.73 to 2.61)	1.71 (1.40 to 2.09)
P for trend	0.60	0.002	0.16	0.32	0.07	0.47	<0.001	0.02	<0.001
BMI (kg/m2)
<18.5	4.25 (3.00 to 6.00)	7.30 (6.51 to 8.17)	11.55 (9.8 to 13.56)	0.56 (0.16 to 1.91)	0.44 (0.20 to 0.95)	0.99 (0.37 to 2.67)	0.23 (0.09 to 0.56)	0.35 (0.21 to 0.61)	0.58 (0.36 to 0.93)
18.5–24.9	4.51 (4.05 to 5.02)	7.44 (6.89 to 8.03)	11.96 (11.01 to 12.98)	0.23 (0.18 to 0.30)	0.44 (0.38 to 0.51)	0.67 (0.58 to 0.78)	0.23 (0.18 to 0.30)	0.68 (0.57 to 0.81)	0.91 (0.78 to 1.07)
≥25	4.97 (4.60 to 5.37)	7.89 (6.95 to 8.95)	12.86 (11.71 to 14.11)	0.27 (0.21 to 0.35)	0.61 (0.47 to 0.78)	0.88 (0.74 to 1.05)	0.29 (0.22 to 0.40)	0.92 (0.77 to 1.09)	1.21 (1.02 to 1.43)
P for trend	0.60	0.002	0.16	0.32	0.07	0.47	<0.001	0.02	<0.001
Income per year, yuan
<10 000	5.09 (4.45 to 5.81)	7.8 (6.95 to 8.75)	12.89 (11.56 to 14.34)	0.18 (0.12 to 0.25)	0.52 (0.42 to 0.65)	0.70 (0.56 to 0.87)	0.34 (0.21 to 0.54)	0.89 (0.71 to 1.11)	1.23 (0.97 to 1.57)
10 000–30000	4.77 (4.11 to 5.52)	7.77 (7.19 to 8.39)	12.54 (11.62 to 13.51)	0.3 (0.21 to 0.43)	0.47 (0.37 to 0.60)	0.77 (0.64 to 0.92)	0.27 (0.16 to 0.47)	0.73 (0.59 to 0.90)	1.00 (0.79 to 1.28)
>30 000	4.60 (4.18 to 5.06)	7.25 (6.56 to 8.01)	11.85 (10.86 to 12.92)	0.32 (0.22 to 0.45)	0.45 (0.37 to 0.56)	0.77 (0.60 to 0.98)	0.24 (0.18 to 0.31)	0.71 (0.58 to 0.88)	0.95 (0.8 to 1.13)
P for trend	0.02	0.006	<0.001	0.21	0.02	0.35	0.03	0.048	0.003
Location
Urban	4.57 (3.99 to 5.23)	7.44 (6.36 to 8.68)	12.01 (10.38 to 13.87)	0.35 (0.25 to 0.49)	0.39 (0.30 to 0.50)	0.73 (0.57 to 0.95)	0.23 (0.17 to 0.32)	0.73 (0.56 to 0.94)	0.96 (0.76 to 1.21)
Rural	4.83 (4.11 to 5.68)	7.52 (6.65 to 8.48)	12.35 (10.81 to 14.06)	0.22 (0.15 to 0.32)	0.55 (0.46 to 0.67)	0.77 (0.62 to 0.96)	0.30 (0.22 to 0.41)	0.78 (0.65 to 0.93)	1.07 (0.88 to 1.30)
P for difference	0.48	0.75	0.61	0.16	0.03	0.58	0.10	0.45	0.21
Inland/coastal
Inland	5.3 (4.82 to 5.84)	8.5 (7.83 to 9.23)	13.81 (12.69 to 15.00)	0.36 (0.25 to 0.52)	0.53 (0.46 to 0.61)	0.90 (0.74 to 1.09)	0.29 (0.22 to 0.38)	0.89 (0.77 to 1.02)	1.17 (1.00 to 1.37)
Coastal	3.81 (3.31 to 4.39)	5.98 (5.24 to 6.82)	9.79 (8.61 to 11.12)	0.17 (0.13 to 0.23)	0.37 (0.27 to 0.50)	0.54 (0.44 to 0.66)	0.24 (0.15 to 0.38)	0.56 (0.42 to 0.75)	0.80 (0.59 to 1.09)
P for difference	< 0.001	<0.001	< 0.001	0.008	0.02	0.002	0.43	0.005	0.02
Cigarette smoking
Never smoked	5.48 (5.06 to 5.92)	7.52 (6.97 to 8 to 10)	12.99 (12.07 to 13.97)	0.32 (0.21 to 0.50)	0.47 (0.41 to 0.54)	0.79 (0.64 to 0.98)	0.27 (0.22 to 0.32)	0.76 (0.66 to 0.87)	1.03 (0.91 to 1.16)
Smoker	3.96 (3.56 to 4.41)	6.30 (4.83 to 8.18)	10.26 (8.77 to 11.97)	0.24 (0.18 to 0.31)	0.38 (0.18 to 0.83)	0.62 (0.39 to 0.99)	0.27 (0.18 to 0.38)	0.64 (0.40 to 1.01)	0.90 (0.63 to 1.30)
P for difference	<0.001	0.20	<0.001	0.32	0.50	0.001	0.86	0.71	<0.001
Consumption of iodised salt
Yes	4.71 (4.37 to 5.08)	7.58 (7.07 to 8.13)	12.30 (11.49 to 13.15)	0.29 (0.22 to 0.38)	0.47 (0.41 to 0.53)	0.75 (0.65 to 0.88)	0.27 (0.21 to 0.35)	0.77 (0.67 to 0.88)	1.04 (0.90 to 1.20)
No	4.03 (2.75 to 5.87)	5.58 (4.01 to 7.71)	9.61 (6.85 to 13.33)	0.20 (0.09 to 0.42)	0.52 (0.29 to 0.96)	0.72 (0.48 to 1.08)	0.21 (0.10 to 0.45)	0.53 (0.29 to 0.96)	0.74 (0.43 to 1.26)
P for difference	0.57	0.03	0.16	0.21	0.72	0.95	0.73	0.27	0.42
AIT status
AIT+	8.89 (8.02 to 9.86)	10.64 (9.82 to 11.53)	19.54 (18.08 to 21.08)	1.27 (0.98 to 1.65)	1.39 (1.14 to 1.69)	2.66 (2.23 to 3.18)	1.48 (1.03 to 2.11)	2.57 (2.12 to 3.10)	4.05 (3.31 to 4.94)
AIT−	4.34 (3.97 to 4.75)	6.68 (6.10 to 7.32)	11.02 (10.11 to 12.01)	0.19 (0.13 to 0.28)	0.23 (0.18 to 0.28)	0.42 (0.33 to 0.53)	0.15 (0.11 to 0.20)	0.28 (0.24 to 0.34)	0.43 (0.36 to 0.52)
P for difference	0.14	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	< 0.001

AIT, autoimmune thyroiditis; BMI, body mass index; OH, overt hypothyroidism; SCH, subclinical hypothyroidism.