Table 3.

A summary of the main features of 60 patients with severe COVID-19 in whom HLH was suspected and details about the fulfilment of the individual HLH classification criteria are available [35, 37, 62, 67–86]

		n/N (%)
Total cases		60 (100)
Country	USA	21 (35)
	Spain	8 (13.3)
	Greece	7 (11.6)
	UK	7 (11.6)
	France	4 (6.6)
	Italy	4 (6.6)
	Iran	2 (3.3)
	Brazil	2 (3.3)
	Belgium	1 (1.6)
	Czech Republic	1 (1.6)
	India	1 (1.6)
	Netherlands	1 (1.6)
	Switzerland	1 (1.6)
Age	Mean age (range)	55,6 (7–91)
Sex	Female	19 (31.7)
Known immuno-suppression		14/42 (33.3)
Fever (°C)	Fever (yes)	42/59 (71.1)
	38–39	12/26 (46.1)
	39–40	6/26 (23)
	> 40	8/26 (30.7)
Megalies	Hepatomegaly	1/25 (4)
	Splenomegaly	5/25 (20)
	Both	6/25 (24)
Cytopenias	Nil lineage (0)	29/56 (51.7)
	One-cell lineage	17/56 (30.3)
	Two-cell lineages	6/56 (10.7)
	Three-cell lineages	4/56 (7.1)
Haemoglobin level	> 12	22/44 (50)
	9–12	8/44 (18.1)
	< 9	14/44 (31.8)
Neutrophils count	Normal	32/35 (91.4)
	≤ 1000	3/35 (8.6)
Platelets count	Normal	25/48 (52.1)
	< 100,000	23/48 (47.9)
Ferritin levels (ng/mL)	High	56/58 (96.6)
	< 500	5/56 (8.9)
	500–1000	9/56 (16.1)
	1000–10,000	28/56 (50.0)
	> 10,000	14/56 (25.0)
Hypertriglyceridaemia (> 256 mg/dL, > 3 mmol/L)	No	19/36 (52.7)
	Yes	17/36 (47.2)
Hypofibrinogenaemia (< 1.5 mg/L, < 150 mg/dL))	No	24/33 (72.7)
	Yes	9/33 (27.2)
AST (IU/l)	< 30	3/42 (7.1)
	> 30	39/42 (92.8)
Low sIL-2R levels and/or reduced NK cell function	Present	0/0 (0)
	Absence	6/6 (100)
Haemophagocytosis Bx	Present	15/18 (83.3)
	Absence	3/18 (16.6)
HLH 2004 (number of criteria fulfilled)*	0	1 (1.7)
	1–2	30 (50)
	3–4	21 (35)
	> 5	8 (13.3)
HScore*	< 90	31 (51.6)
	100–160	22 (36.6)
	> 169	7 (11.6)
Outcome	ICU discharge	24/60 (40)
	Death	28/60 (46.6)

*Most patients have no data on several HLH criteria (especially biopsy carried out in only 30% of patients, and measurement of NK function and sCD35 levels, measured in only 5%)