Table 2.

Quality assessment result of observational studies (n = 93) using the Newcastle-Ottawa Scale:

	Study	Representativeness of the sample (One Point)	Sample Size (One Point)	Non-Respondents (One Point)	Ascertainment of the exposure (One Point)	Study controls for other variable (Two Point)	Assessment of Outcome (One Point)	Statistical Test (One Point)	Adequate Follow up time (One Point)	Score
1	Cai et al., (2020)	1	1	1	0	0	0	1	1	5	Moderate
2	Z. Zhu et al., (2020)	1	1	1	1	1	1	1	0	7	Low
3	Choudhury et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
4	Lai et al., (2020)	1	1	1	1	2	1	1	0	8	Low
5	Liu et al., (2020)	1	1	1	1	1	1	1	0	7	Low
6	Yin et al., (2020)	1	1	0	1	1	1	1	0	6	Moderate
7	J. Zhu et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
8	Guo et al., (2020)	1	1	1	1	2	1	1	0	8	Low
9	Xiao et al., (2020)	1	1	1	1	1	1	1	0	7	Low
10	Wang et al., (2020)	0	1	1	1	1	1	1	0	6	Low
11	Wang et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
12	Zhang et al., (2020)	1	1	1	1	1	0	1	0	6	Moderate
13	Mo et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
14	Huang et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
15	García-Fernández et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
16	Szepietowski et al., (2020)	0	1	1	0	1	1	1	0	5	Moderate
17	Cui et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
18	Du et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
19	Zhou et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
20	Jiang et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
21	R. Zhang et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
22	S. X. Zhang et al., (2020)	0	1	1	0	1	1	1	0	5	Moderate
23	Wan et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
24	Taghizadeh et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
25	S. X. Zhang et al.,(2020a)	0	1	1	1	1	0	1	1	6	Moderate
26	Salman et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
27	Zhpu et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
28	Pan et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
29	Ning et al.,(2020)	1	1	1	1	1	1	1	0	7	Low
30	Y. Liu et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
31	Otgonbaatar et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
32	Li et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
33	Lv et al., (2020)	1	1	1	1	2	1	1	0	8	Low
34	Hu et al., (2020)	1	1	1	1	2	1	1	0	8	Low
35	B. Wang et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
36	W. Zhang et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
37	Weilenmann et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
38	Sahin et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
39	Rossi et al., (2020)	1	1	1	1	2	1	1	0	8	Low
40	Kaveh et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
41	Guixia and Hui, (2020)	0	1	1	1	1	0	1	0	5	Moderate
42	Al Amer et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
43	Shechter et al., (2020)	1	1	1	1	2	1	1	0	8	Low
44	Naser et al., (2020)	1	1	0	1	1	1	1	0	6	Moderate
45	Que et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
46	Jahrami et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
47	Koksal et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
48	Tu et al., (2020)	1	1	1	1	1	1	1	0	7	Low
49	Yang et al., (2020)	1	1	0	1	1	1	1	0	6	Moderate
50	Chekole et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
51	Fang et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
52	Jia et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
53	Zerbini et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
54	Pouralizadeh et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
55	Gallopeni et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
56	Li et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
57	Chorwe-Sungani, (2020)	0	1	1	1	1	0	1	0	5	Moderate
58	Saricam, (2020)	0	1	1	1	1	0	1	0	5	Moderate
59	Arafa et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
60	Silwal et al., (2020)	1	1	1	0	0	0	1	1	5	Moderate
61	Li et al., (2020)	1	1	1	1	1	1	1	0	7	Low
62	Hong et al., (2020)	1	1	1	1	2	1	1	0	8	Low
63	Hoedl et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
64	Xiaozheng et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
65	Zhan et al., (2020)	1	1	1	1	1	1	1	0	7	Low
66	AlAteeq et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
67	Khanal et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
68	Bachilo et al., (2020)	0	1	1	0	1	1	1	0	5	Moderate
69	Wanigasooriya et al., (2020)	1	1	1	0	0	0	1	1	5	Moderate
70	Leng et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
71	Aksoy and Koçak, (2020)	0	1	1	0	1	1	1	0	5	Moderate
72	Hendy et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
73	Zhan et al., (2020b)	1	1	1	1	2	1	1	0	8	Low
74	Skoda et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
75	Nie et al., (2020)	1	1	1	0	0	0	1	1	5	Moderate
76	Zhu et al., (2020)	1	1	1	1	1	1	1	0	7	Low
77	Chen et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
78	Tselebis et al., 2020)	0	1	1	0	1	1	1	0	5	Moderate
79	Prasad et al., 2020)	0	1	1	1	1	0	1	1	6	Moderate
80	Lee et al., 2020)	0	1	1	1	1	0	1	0	5	Moderate
81	Azoulay et al., (2020)	0	1	1	0	1	1	1	0	5	Moderate
82	Xiong et al., (2020)	0	1	1	0	1	1	1	0	5	Moderate
83	Sampaio et al., (2020)	0	1	1	1	1	0	1	1	6	Moderate
84	Buselli et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
85	Salopek-Žiha et al., (2020)	0	1	1	0	1	1	1	0	5	Moderate
86	Wasim et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
87	Ahn et al., (2020)	0	1	1	1	1	0	1	0	5	Moderate
88	Zheng et al., (2020)	1	1	1	1	2	1	1	0	8	Low
89	Gorini et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
90	An et al., (2020)	0	1	0	1	2	1	1	0	6	Moderate
91	Zhang et al., (2020)	0	1	1	1	1	1	1	0	6	Moderate
92	Ruiz-Fernández et al., (2020)	0	1	1	0	1	1	1	0	5	Moderate
93	Han et al., (2020)	1	1	1	1	2	1	1	0	8	Low