Table 2.

Subgroup meta-analysis of serum vitamin D level and vitamin D deficiency

	Vitamin D					Vitamin D deficiency
	No. of articles	WMD (95%CI)	p	I2 (%)	pheterogeneity	No. of articles	OR (95% CI)	p	I2 (%)	pheterogeneity
Overall	17	− 9.08 (− 11.66, − 6.50)	< 0.001	87.90	< 0.001	13	4.14 (2.34, 7.35)	< 0.001	81.10	< 0.001
Design
Case–control	14	− 9.05 (− 12.46, − 5.63)	< 0.001	89.70	< 0.001	11	3.66 (2.06, 6.49)	< 0.001	78.80	< 0.001
Cross-sectional	3	− 9.82 (− 11.91, − 7.72)	< 0.001	40.20	0.188	2	6.65 (0.65, 68.27)	0.111	84.90	0.01
Sample size
≤  100	12	− 9.59 (− 13.44, − 5.74)	< 0.001	90.50	< 0.001	6	5.36 (1.29, 22.21)	0.021	76.50	0.001
> 100	5	− 8.35 (− 11.19, − 5.51)	< 0.001	75.50	< 0.001	7	3.94 (2.06, 7.54)	< 0.001	85.70	< 0.001
Controls
Matched	12	− 11.38 (− 13.99, − 8.78)	< 0.001	84.60	< 0.001	9	6.96 (3.54, 13.68)	< 0.001	80.80	< 0.001
Not matched	5	− 3.18 (− 8.35, 1.99)	0.228	84.10	< 0.001	4	1.52 (1.00, 2.32)	0.052	1.10	0.386
Male ratio
> 1/2	11	− 7.79 (− 11.47, − 4.11)	< 0.001	88.60	< 0.001	10	4.51 (2.05, 9.93)	< 0.001	83.10	< 0.001
≤ 1/2	5	− 12.03 (− 16.93, − 7.13)	< 0.001	86.00	< 0.001	3	3.24 (1.37, 7.63)	0.007	0.3767	0.012
NR	1	− 8.89 (− 10.56, − 7.22)	< 0.001
Mean age (years)
> 25	14	− 10.06 (− 12.87, − 7.24)	< 0.001	87.50	< 0.001	12	3.58 (2.04, 6.28)	< 0.001	78.30	< 0.001
≤ 25	3	− 4.49 (− 13.24, 4.25)	0.314	91.40	< 0.001	1	16.43 (6.65, 40.61)	< 0.001
Country
Nepal	1	− 9.68 (− 19.62, 0.26)	0.056			1	4.38 (1.32, 14.50)	0.016
India	5	− 8.73 (− 11.59, − 5.87)	< 0.001	81.80	< 0.001	3	2.55 (1.54, 4.21)	< 0.001	29.10	0.244
Turkey	4	− 3.37 (− 10.68, 3.94)	0.366	94.0	< 0.001	2	2.97 (0.06, 147.87)	0.585	94.1	< 0.001
Egypt	5	− 14.75 (− 22.10, − 7.39)	< 0.001	90.60	< 0.001	4	8.91 (1.20, 66.39)	0.033	86.9	< 0.001
Pakistan	1	− 9 (− 15.55, − 2.45)	0.007
Israel	1	− 10.23 (− 17.51, − 2.95)	0.006			1	6.86 (1.78, 26.36)	0.005
Italy						1	1.73 (1.08, 2.79)	0.023
USA						1	4.37 (2.71, 7.04)	< 0.001

WMD weighted mean difference, OR odds ratio, CI confidence interval