Prognostic significance of red blood cell distribution width in gastrointestinal disorders

Table 1 Published studies on role of red blood cell distribution width in inflammatory bowel disease

Ref.	No. of subjects	Study period	Activity index	Outcome measures	RDW Value	Statistics		Other laboratory studies	Main findings
						Sensitivity (%)	Specificity (%)
Clarke et al[21], 2008	156 CD	January 1st 2004 to December 31st 2005		Differential diagnosis CD vs UC	CD 14.9 UC 14.3	P = 0.027			RDW value was significantly higher in CD relative to ulcerative colitis patients
	128 UC
Cakal et al[23], 2009	74 UC, 22 CD, and 20 age/sex-matched controls		CDAI					CRP, ESR, Fibrinogen, PLT, WBC, Hb	RDW and CRP were the most significant indicators of active UC and active CD, respectively
			> 150 = active	Active UC or CD	UC 14	88	71
			Truelove-Witts scale for UC moderate and severe = active		CD 14.1	78	63
Oustamanolakis et al[28], 2011	51 CD		CDAI	Anemia (IDA/ACD)	14 (cut off)	93	81	Ferritin, Tsat, sTfR	High RDW and low RSF values were the best markers for the diagnosis of IDA
	49 UC		> 150 active	IDA				RDWR-C, RSF, IRF,
	102 age matched controls		< 150 inactive					Hb, ESR
			Simple Clinical					CRP
			Colitis Activity Index for UC
			Active ≥ 3
Yeşil et al[24], 2011	56 CD		CDAI	Active UC/CD	14 (cut off )	79 (CD)	93 (CD)	CRP, ESR, PLT, Hb	RDW was elevated in IBD and markedly increased in active disease. RDW may be a marker of active CD, whereas ESR is for active UC
	61 UC		> 150 = active			17 (UC)	84 (UC)
	44 age/sex matched controls		Truelove-Witts scale for UC
Song et al[26], 2012	101 CD	January 2003 and December 2010	CDAI	Active UC/CD	14.1 CD without anemia (cut off)	82 (CD)	83 (CD)	CRP, ESR, PLT, WBC, Hb,	RDW was associated with active CD/UC in patients with or without anemia
	120 UC		remission < 150, mild 150-220, moderate to severe ≥ 220; Mayo score for UC		13.8 UC without anemia (cut off )
			remission < 3, mild 3-6, moderate to severe ≥ 6			76 (UC)	86 (UC)
Ipek et al[25], 2015	206 active UC	January 2009 to December 2011	Endoscopic Rachmilewitz activity index > 4 = Active UC		Active UC 16.8			CRP, ESR, PLT, WBC, Hb	RDW can be used as a marker for disease activity in ulcerative colitis, but not in the non-anemic group
	104 remission UC			Active UC vs remission	Remission UC 15.5	P < 0.001
Oliveira et al[27], 2016	20 Active CD	January 1st and September 30th 2013	CDAI	RDW association with Active CD	16 (Cut off )	30	88	CRP, ESR, PLT, WBC, Hb, MCV	RDW was associated with the severity of CD. The RDW cutoff 16% showed possible clinical applicability
	99 remission CD		≥ 150 = active CD

CD: Crohn’s disease; UC: Ulcerative colitis; CDAI: Crohn’s disease activity index; CRP: C-reactive protein; ESR: Erythrocyte Sedimentation Rate; PLT: Platelets; WBC: White blood cells; Tsat: Transferrin saturation; sTfR: Soluble transferrin receptor; RSF: Red blood cell size factor; IRF: Immature reticulocyte fraction; RDWR-CV: Reticulocyte distribution width-coefficient of variation; IDA: Iron deficiency anemia; ACD: Anemia of chronic disease.