Table 1. Main characteristics of the included studies in meta-analysis.

Study	Year	Country	Sample (n)	Male	ICI users	Age	Study type	Outcome	Treatment interval before diagnosis	NOS
Albiges et al.	2020	France	178	76	19	61 (IQR 52–71)	Retrospective	Severity and mortality	3 months	8
Bersanelli et al.	2020	Italy	9	8	9	75 (range 50–82)	Prospective	Mortality	21 weeks	6
Dai et al.	2020	China	641	302	6	Male median: 64 Female median: 63.5	Prospective	Mortality and severity	40 days	8
Lara et al.	2020	USA	121	NR	8	64 (IQR 51–73)	Retrospective	Hospitalization, severity and mortality	NR	5
Lee et al.	2020	UK	800	449	44	69 (range 59–76)	Prospective	Mortality	4 weeks	8
Lievre et al.	2020	France	1289	795	110	67 (range 19–100)	Prospective	Mortality	3 months	9
Luo et al.	2020	USA	69	33	40	69 (range 31–91)	Retrospective	Hospitalization, severity and mortality	6 weeks (n = 20); 6 months (n = 30); ongoing (n = 40).	6
Moritz et al.	2020	Germany	13	7	13	65 (range 26–88)	Retrospective	Severity and mortality	51 days	6
Noguera et al.	2020	Spain	166	96	58	63 (range 33–86)	Retrospective	Hospitalization	2 months	7
Pinato et al.	2020	UK, Italy, Spain and Germany	890	503	56	68 (range 21–99)	Retrospective	Mortality	4 weeks	6
Robilotti et al.	2020	USA	423	212	31	416 pts >18 (98%) 234 pts >60 (56%)	Retrospective	Hospitalization and Severity	90 days	5
Szabados et al.	2020	UK	4	4	4	67 (range 52–72)	Prospective	Hospitalization, severity and mortality	90 days	5
Wu et al.	2020	China	11	8	11	66 (range 29–73)	Retrospective	Severity and mortality	50 days	5

ICI: Immune checkpoint inhibitor; IQR: Interquartile range; NR: Not reported; NOS: Newcastle–Ottawa Scale; pts: Patients.