Red cell distribution width as a biomarker of disease activity in ulcerative colitis and Crohn’s disease

Table 1 Baseline demographic, laboratory, and activity characteristics of the study population, median (interquartile range)

Variable	Ulcerative colitis (n = 365)	Crohn’s disease (n = 90)	P value
Age (years)	43.0 (32-58)	43.0 (34-55)	0.59
Sex, male (%)	58.4	53.3	0.39
Platelet (× 103/μL)	293 (241-351)	299 (244-376)	0.36
CRP (mg/L)	3.7 (1.3-10.3)	4.8 (1.5-15.6)	0.08
RDW-CV (%)	13.3 (12.9-14.5)	13.9 (13.1-15.5)	0.008
RDW-SD (fL)	41.8 (39.8-44.2)	43.4 (40.8-46.9)	< 0.001
Remission (%)	30.1	26.7	0.52
Active disease (%)	69.9	73.3

RDW-CV: Red cell distribution width-coefficient of variation; RDW-SD: Red cell distribution width-standard deviation; CRP: C-reactive protein.

Table 2 Red cell distribution width and laboratory parameters across ulcerative colitis disease activity groups, median (interquartile range)

Variable	Remission (n = 110)	Mild (n = 75)	Moderate (n = 116)	Severe (n = 64)	P value
RDW-CV (%)	13.1 (12.7-13.7)	13.2 (12.8-13.9)	13.6 (13.0-14.8)	14.2 (13.4-16.0)	< 0.001
RDW-SD (fL)	41.5 (39.5-43.5)	41.2 (39.4-43.4)	42.1 (40.1-44.3)	42.8 (40.5-45.3)	0.32
CRP (mg/L)	1.2 (0.5-3.2)	2.4 (0.8-6.4)	6.7 (2.6-15.1)	11.8 (4.9-27.8)	< 0.001
Platelets	275 (230-324)	286 (239-342)	302 (254-357)	338 (276-396)	< 0.001

Disease activity was classified according to the ulcerative colitis endoscopic index of severity. RDW-CV: Red cell distribution width-coefficient of variation; RDW-SD: Red cell distribution width-standard deviation; CRP: C-reactive protein.

Table 3 Red cell distribution width and laboratory parameters across Crohn’s disease activity groups, median (interquartile range)

Variable	Remission (n = 24)	Mild (n = 35)	Moderate (n = 24)	Severe (n = 7)	P value
RDW-CV (%)	13.8 (12.9-14.8)	13.6 (13.0-14.8)	14.3 (13.5-16.7)	15.2 (14.1-16.2)	0.02
RDW-SD (fL)	43.0 (40.2-45.4)	42.6 (40.4-46.0)	43.9 (41.1-48.6)	45.3 (41.0-48.9)	0.56
CRP (mg/L)	2.0 (0.9-7.7)	4.7 (1.7-13.0)	11.8 (4.6-32.7)	18.4 (7.2-41.5)	< 0.001
Platelets	265 (224-322)	298 (251-348)	321 (263-389)	369 (298-414)	< 0.001

Disease activity was categorized according to the Crohn’s disease activity index. RDW-CV: Red cell distribution width-coefficient of variation; RDW-SD: Red cell distribution width-standard deviation; CRP: C-reactive protein.

Table 4 Red cell distribution width comparison between remission and active disease in ulcerative colitis and Crohn’s disease, median (interquartile range)

Variable	Remission	Active disease	P value
UC: RDW-CV (%)	13.1 (12.7-13.7)	13.6 (13.0-15.0)	0.002
UC: RDW-SD (fL)	41.5 (39.5-43.5)	42.0 (40.0-44.7)	0.30
CD: RDW-CV (%)	13.8 (12.9-14.8)	14.2 (13.3-15.8)	0.25
CD: RDW-SD (fL)	43.0 (40.2-45.4)	43.4 (40.6-47.1)	0.75

RDW-CV: Red cell distribution width-coefficient of variation; RDW-SD: Red cell distribution width-standard deviation; UC: Ulcerative colitis; CD: Crohn’s disease.