Red blood cell distribution width in heart failure: A narrative review

Table 1 Differential diagnosis of anemia based on mean corpuscular volume and red blood cell distribution width

Conditions	MCV	RDW
Chronic diseases anemia	↓	N
Heterozygous thalassemia	↓	N
Iron deficiency	↓	↑
β-thalassemia	↓	↑
Sickle cell trait	↓	N
Haemolytic anemia	N/↓	↑
Hereditary spherocytosis	N/↓	↑
Sickle cell disease	N	↑
Haemorrhage	N	N
Blood transfusions	N	↑
Chronic liver disease	N/↑	↑
Aplastic anemia	↑	N
Folate deficiency	↑	↑
Vitamin B12 deficiency	↑	↑
Myelodysplastic syndrome	↑	↑

MCV: Mean corpuscular volume; RDW: Red blood cell distribution width; N: Normal; ↓: Decreased; ↑: Increased.

Table 2 Meta-analyses exploring the association between baseline red blood cell distribution width value and heart failure

Ref.	Variable	Outcome measure	Baseline RDW
Huang et al[28], 2014	1% increase in RDW value	Risk of future death in patients with HF	HR, 1.10 (95%CI: 1.07-1.13)
		Risk of hospitalization in patients with HF	HR, 1.09 (95%CI: 1.03-1.16)
Shao et al[29], 2015	1% increase in RDW value	Risk of future MACE in patients with HF	HR, 1.19 (95%CI: 1.08-1.30)
		Risk of future death in patients with HF	HR, 1.12 (95%CI: 1.08-1.16)
Hou et al[30], 2017	1% increase in RDW value	General risk of HF	HR, 1.11 (95%CI: 1.05-1.17)
			HR, 1.11 (95%CI: 1.04-1.14)

HF: Heart failure; HR: Hazard ratio; MACE: Major adverse cardiovascular events; RDW: Red blood cell distribution width.

Table 3 Studies exploring the association between serial red blood cell distribution width changes and heart failure

Ref.	Study design	Outcome measure	Variable	Baseline RDW	Longitudinal RDW change
Cauthen et al[31], 2012	Retrospective, 6159 patients with chronic HF	1-year all-cause mortality	1% increase in RDW at diagnosis or during 1 year of follow-up	RR, 1.09 (95%CI: 1.01-1.17)	RR, 1.21 (95%CI: 1.08-1.34)
Makhoul et al[32], 2013	Prospective, 614 patients with acute decompensated HF followed-up during hospital stay	All-cause mortality during hospital stay	1% increase in RDW value at admission or during hospital stay	HR, 1.15 (95%CI: 1.08-1.21)	HR, 1.23 (95%CI: 1.09-1.38)
Núñez et al[33], 2014	Prospective, 1702 patients with HF followed-up for 18 mo	All-cause mortality during follow-up	RDW ≥ 15% at admission or during follow-up	Anemic patients: HR, 1.04 (95%CI: 1.00-1.07)Non-anemic patients: HR, 1.11 (95%CI: 1.05-1.19)	Anemic patients: HR, 1.08 (95%CI: 1.04-1.13)Non-anemic patients: HR, 1.31 (95%CI: 1.22-1.42)
Ferreira et al[35], 2016	Retrospective, 502 patients with acute decompensated HF	Hospitalization for acute decompensated HF or 180-d cardiovascular death	RDW ≥ 15% at admission and delta RDW > 0 at discharge	OR, 1.29 (95%CI: 0.71-2.33)	OR, 2.47 (95%CI: 1.35-4.51)
Muhlestein et al[34], 2016	Prospective, 6414 patients with HF followed-up during hospital stay	30-d all-cause mortality	1% increase in RDW value at admission and during hospital stay	HR, 1.09 (95%CI: 1.07-1.12)	HR, 1.09 (95%CI: 1.03-1.16)
Uemura et al[36], 2016	Prospective, 229 patients with acute decompensated HF followed-up followed for 692 d	All-cause mortality during follow-up	RDW ≥ 14.5% at admission and positive change of RDW at discharge	HR, 1.08 (95%CI: 0.99-1.19)	HR, 1.19 (95%CI: 1.01-1.41)
Turcato et al[37], 2017	Retrospective, 588 patients with acute decompensated HF	30-d all caused mortality	ΔRDW > 0.4% at 48 and 96 h	-	OR, 3.04 (95%CI: 1.56-5.94) and 3.65 (95%CI: 2.02-6.15)

HF: Heart failure; HR: Hazard ratio; OR: Odds ratio; RDW: Red blood cell distribution width; RR: Relative risk.