Table 1. . Summary of the included studies and their population characteristics.

Study	Type of study	Country	Patients (n)	Age (years), mean (± SD)		Gender (males)		Medical history		Severe COVID-19
				AIS	Non-AIS	AIS	Non-AIS	AIS	Non-AIS	AIS	Non-AIS
Annie et al. (2020)	Retrospective observational study	USA	AIS = 64 non-AIS = 9294 total = 9358	39.3 (± 9.0)	36.7 (8.5)	25	3680	Smoking (22), HTN (39), DM (21), obesity (30)	Smoking (548), HTN (1087), DM (604), obesity (1617)	NA	NA
Fan et al. (2020)	Retrospective observational study	China	AIS = 6, non-AIS = 80 total = 86	68.2 (± 2.1)	66.5 ± 11.5	5	49	Smoking (1), HTN (3), DM (2)	Smoking (11), HTN (41), DM (17)	NA	NA
Hernández-Fernández et al. (2020)	Retrospective observational study	Spain	AIS = 17, non-AIS = 1667 total = 1684	68.2 (± 13.0)	NA	13	NA	Smoking (2), HTN (10), DM (6), dyslipidemia (7)	NA	NA	NA
Zhang et al. (2020)	Single-center case series	China	AIS = 39, non-AIS = 612 total = 651	Median (IQR) 70 (67–84)	Median (IQR) 55 (37–67)	33	259	HTN (43), DM (19)	HTN (183), DM (93)	6	167
Li et al. (2020)	Retrospective observational study	China	AIS = 10, non-AIS = 209 total = 219	75.7 (± 10.8)	52.1 (15.3)	5	83	Smoking (3), HTN (9), DM (6), heart disease (3), malignancy (1)	HTN (46), DM (25), heart disease (14), malignancy (13)	9	83
Lodigiani et al. (2020)	Retrospective observational study	Italy	AIS = 9, non-AIS = 353 yotal = 362	NA	NA	NA	NA	NA	NA	3	58
Bach et al. (2020)	Retrospective observational study	USA	AIS = 20, non-AIS = 663 total = 683	63 (± 10.7)		13	384	Smoking (5), HTN (18), DM (13), dyslipidemia (8), obesity (17)	NA	NA	NA
Shahjouei et al. (2020)	Retrospective observational study	Multiple countries	AIS = 123, non-AIS = 6233 total = 6356	68.6 (13.9)	58 (14)	67	3688	Smoking (15), HTN (61), DM (32)	Smoking (385), HTN (1912), DM (1312)	NA	NA

AIS: Acute ischemic stroke; DM: Diabetes milletus; HTN: Hypertension; IQR: Interquartile range; NA: Not available.