Table 3. Haemocytometric COVID-19 prognostic score cut-off values.

	Variable	Precondition	1 Point	2 Points	3 Points	4 Points
Primary Variables	IG/L*100	IG* ≥ 0,09	≥10	≥20	≥40	≥45
	NLR	none	[<7,7 and LYMPH† < 1,07 and N/L²≥7,5] or [≥7,7 < 16,5 and LYMPH† < 0,65]	[≥7,7 < 16,5 and LYMPH† ≥ 0,65]	[≥7,7 < 16,5 and LYMPH† ≥ 1,07]	≥16,5
	RE-MONO/M [%]	none	[≥5 < 15 and RE-MONO‡ < 0,03]	[≥5 < 15 and Re-MONO‡ ≥ 0,03]	n/a	≥15
	AS-LYMPH/L [%]	none	[≥5 and LYMPH§ < 10]	≥10	n/a	≥15
	DELTA-He [pg]	RET¶ ≥ 6.0	[< −1 ≥ −2] or [<0,4 ≥ −1 and RET¶ ≥ 20.0]	[< −2 ≥ −4]	n/a	< −4
	NRBC [/µL]	HGB** ≥ 9 and RET¶ < 90	n/a	≥ 20	n/a	≥40
Secondary Variables	HGB [g/dl]	none	≥17
	HYPO-He [%]	Micro-R†† < 10	≥1,9
	PLT [10³/µL]	none	<85
	IPF# [10³/µL]	none	≥25

Note: For the primary variables, one point = value above the cut-off value for the best AUC; two points = value above the cut-off value for the best AUC and ≥80% specificity; three points = value above the cut-off value for the best AUC and >90% specificity; and four points = value above the cut-off value for the best AUC and >95% specificity. The cut-off values for the secondary variables were chosen exclusively based on observed extremes of values in critical disease, with the maximum award of 1 point per variable.

The prognostic score values were calculated automatically using a pre-set algorithm, using the above cut-off values to assign points per individual parameter. The aim is to have the formula for the calculation incorporated into the Laboratory Information System software in use in individual laboratories.

Abbreviations: IGLR, immature granulocytes-to-lymphocyte ratio; NLR, neutrophil-to-lymphocyte ratio; AS-LYMPH%/L, antibody synthesising lymphocytes as a proportion of lymphocytes; RE-MONO%/M, reactive monocytes as a proportion of monocytes; DELTA-He, difference in haemoglobinisation of reticulocytes and red blood cells; NRBC, absolute nucleated red blood cell count; HGB, haemoglobin; HYPO-He, percentage of red blood cells that are hypochromic; PLT, platelet count; IPF, absolute immature platelet count; N/L², neutrophil-to-lymphocyte squared ratio.

* Unit of measure for IG (absolute immature granulocyte count) is x 10³/µL.

† Unit of measure for LYMPH (absolute lymphocyte count) is x 10³/µL.

‡ Unit of measure for RE-MONO (absolute reactive monocyte count) is x 10³/µL.

§ Unit of measure for LYMPH% (percentage lymphocyte count).

¶ Unit of measure for RET (absolute reticulocyte count) is x 10³/µL.

** Unit of measure for HGB (haemoglobin) is g/dL.

†† Unit of measure for Micro-R is %.