Table 1. Basic information of included studies.

Study	Year	Country	No. patients (severe/non-severe)	Follow-up (days)	Sex	Age, median [IQR] or mean ± SD	Research type	Literature quality
Wan et al. (3)	2020	China	135 (40/95)	17	Male: 72; female: 63	47 [36–55]	Retrospective study	8
Qin et al. (4)	2020	China	452 (286/166)	33	Male: 235; female: 217	58 [47–67]	Retrospective study	6
Guan et al. (5)	2020	China	1,099 (173/926)	28	Male: 640; female: 459	47.0 [35.0–58.0]	Retrospective study	9
Zhang et al. (6)	2020	China	140 (58/82)	18	Male: 71; female: 69	57 [25–87]	Retrospective study	8
Tian et al. (7)	2020	China	262 (46/216)	21	Male: 127; female: 135	47.5 [1–94]	Retrospective study	7
Zhang et al. (8)	2020	China	95 (32/63)	N/A	Male: 53; female: 42	49.0 [39.0–58]	Retrospective study	9
Chu et al. (9)	2020	China	54 (43/11)	35	Male: 36; female: 18	39 [26–73]	Retrospective study	8
Wu et al. (10)	2020	China	280 (83/197)	30	Male: 151; female: 129	43.12±19.02	Retrospective study	7
Wang et al. (11)	2020	China	138 (36/102)	34	Male: 75; female: 63	56 [42–68]	Retrospective study	7
Huang et al. (12)	2020	China	41 (13/28)	17	Male: 30; female: 11	49.0 [41.0–58.0]	Retrospective study	7
Zheng et al. (13)	2020	China	161 (30/131)	21	Male: 80; female: 81	45 [33.5–57]	Retrospective study	8
Mao et al. (14)	2020	China	214 (88/126)	34	Male: 87; female: 127	52.7±15.5	Retrospective study	7
Du et al. (15)	2020	China	109 (51/58)	N/A	Male: 74; female: 35	70.7±10.9	Retrospective study	7
Feng et al. (16)	2020	China	476 (124/352)	35	Male: 271; female: 205	53 [40–64]	Retrospective study	9
Chen et al. (17)	2020	China	21 (11/10)	N/A	Male: 17; female: 4	56.0 [50.0–65.0]	Retrospective study	8
Cai et al. (18)	2020	China	298 (58/240)	26	Male: 145; female: 153	47.5 [33–61]	Retrospective study	7