. 2017 Dec 29;17:179. doi: 10.1186/s12874-017-0454-x

Table 1.

Summary of basic characteristics of 10 included meta-analyses

Study	Year	Country	Summary OR	95% CI		Test of heterogeneity	Crude or adjusted OR to combined^a	AMSTAR score
Study	Year	Country	Summary OR	Lower	Upper	Test of heterogeneity	Crude or adjusted OR to combined^a	AMSTAR score
Lee PN [14]	2016	UK	1.22	1.09	1.37	No exact value, P < 0.001	Mixed OR	6
Chen Z [17]	2015	China	1.67	1.27	2.21	χ² = 64.71, P < 0.00001	Mixed OR	9
Macacu A [15]	2015	France	1.30	1.10	1.54	χ² = 91.85, P < 0.0001	Mixed OR	8
Chen C [16]	2014	China	1.54	1.35	1.73	I² = 7.9%, P = 0.367	All adjusted OR	9
Ma J [18]	2011	China	1.23	1.12	1.40	χ² = 32.68, P = 0.000	Mixed OR	6
Pirie K [19]	2008	UK	1.21	1.11	1.32	χ² = 13.8, P = 0.0002	All adjusted OR	6
Sadri G [20]	2007	Iran	1.38	1.16	1.65	χ² = 5.83, P = 0.32	All adjusted OR	6
Zhou XB [21]	2006	China	1.94	1.80	2.10	χ² = 20.13, P < 0.01	All crude OR	7
Johnson KC [22]	2005	Canada	1.90	1.53	2.37	No exact value, P < 0.05	Mixed OR	6
Khuder SA [23]	2001	USA	1.41	1.14	1.75	χ² = 34.6, P < 0.01	Mixed OR	7

All crude OR: using only crude OR of original studies to combining summary effect size

All adjusted OR: using only adjusted OR of original studies to combining summary effect size

Mixed OR: using mixed crude OR and adjusted OR of original studies to combining summary effect size

^a CI confidence interval, AMSTAR A measurement tool to assess systematic reviews