Table 1

(A) aSAH admissions overall and monthly volumes before and during the COVID-19 pandemic. (B) SAH admissions by severity: overall and monthly volumes before and during the COVID-19 pandemic

(A)
	N	Overall volume				Monthly volume*
		Before COVID-19†	During COVID-19‡	Change	P value	N	Before COVID-19	During COVID-19	P value
		Before COVID-19†	During COVID-19‡	% (95% CI)	P value	N	Adjusted mean (SE)
Overall	165	6912	6471	−6.4 (−7.0 to −5.8)	0.0001	172	3.84 (0.75)	3.62 (0.74)	0.03
Hospital aSAH volume§
Low	56	422	471	11.6 (8.9 to 15.0)	0.101	57	0.56 (0.09)	0.64 (0.11)	0.142
Int.	53	1460	1472	0.82 (0.47 to 1.4)	0.825	56	2.28 (0.12)	2.28 (0.15)	0.977
High	56	5030	4528	−10.0 (−10.8 to −9.2)	<0.0001	59	8.14 (1.41)	7.42 (1.39)	0.008
Hospital aSAH volume stratified by hospital COVID-19 volume¶
Low	49	1788	1833	2.5 (1.9 to 3.4)	0.455	52	2.94 (1.02)	3.0 (1.03)	0.657
Int.	46	1456	1368	−6.0 (−7.4 to −4.9)	0.098	46	2.19 (0.73)	2.03 (0.68)	0.19
High	47	2275	2074	−8.8 (−10.1 to −7.7)	0.002	49	3.77 (1.18)	3.40 (1.15)	0.137

(B)
	N	Overall volume				Monthly volume*
		Before COVID-19†	During COVID-19‡	Change	P value	N	Before COVID-19	During COVID-19	P value
		Before COVID-19†	During COVID-19‡	% (95% CI)	P value	N	Adjusted mean (SE)
Mild	125	2698	2562	−5.0 (−5.9 to −4.3)	0.061	125	1.92 (0.37)	1.83 (0.36)	0.205
Mod.	125	981	900	−8.3 (−10.2 to −6.7)	0.062	125	0.60 (0.09)	0.55 (0.09)	0.204
Severe	125	1508	1490	−1.2 (−1.9 to −0.75)	0.742	125	0.87 (0.16)	0.86 (0.17)	0.78

Table 1b: Mild, moderate and severe cases were defined as Hunt-Hess grades 1–2, 3 and 4–5, respectively. 125 hospitals submitted complete data 12-month prepandemic and pandemic data on grades.
*The monthly volume analysis is adjusted for the date of peak COVID-19 volume for each country, the start date of the second wave and the continent.
†Number of admissions during 12 months before COVID-19 pandemic.
‡Number of admissions during 12 months of COVID-19 pandemic;.
§P value: low versus int. ≤0.0001; low versus high=N/A; int. versus high=N/A.
¶P value: low versus int.=N/A, low versus high=N/A, int. versus high=0.002.
aSAH, aneurysmal subarachnoid haemorrhage; int., intermediate; mod., moderate; N/A, not applicable; n, number of hospitals; SAH, subarachnoid haemorrhage.