Chronic fatigue is associated with increased disease-related worries and concerns in inflammatory bowel disease

Table 1 Main characteristics of the questionnaires used in this study

Questionnaire	Number of items and dimensions	Main characteristics
SF-36 Ware et al[11]	36 items, divided into 8 dimensions	Measure generic HRQoL Scale scores from 0-100, with higher scores indicating better HRQoL
N-IBDQ Bernlev et al[17]	32 items, divided into 5 dimensions	Measure disease-specific HRQoL Scale scores from 32-224, with higher scores indicating better HRQoL
FQ Chalder et al[14] Jelsness-Jørgensen et al[10]	11 items, divided into 2 dimensions The FQ contains 2 items asking about duration and extent of fatigue symptoms	Measure both physical and mental fatigue Scale scores from 0-33 with higher scores indicating higher levels of fatigue In addition scored as a dichotomized scale where original scores 0 + 1 = 0 and 2 + 3 = 1 Chronic fatigue defined as a score of ≥ 4 on the dichotomized scale and duration of fatigue symptoms ≥ 6 mo
RFIPC Drossman et al[7]	25 items, divided into 6 dimensions	Measure the 25 most frequently reported disease-related worries/concerns by IBD patients

IBD: Inflammatory bowel disease; SF-36: Short-Form 36; N-IBDQ: IBD questionnaire (Norwegian version); FQ: Fatigue questionnaire; RFIPC: Rating form of IBD patient concerns; HRQoL: Health-related quality of life.

Table 2 Main clinical/sociodemographic characteristics n (%)

	UC	CD
	(n = 92)	(n = 48)
Age, (yr), mean ± SD	46.9 ± 5.8	40.0 ± 15.0
Age range, (yr)	20-82	19-69
Gender
Female	43 (47)	36 (75)
Male	49 (53)	12 (25)
Disease duration, (yr), mean ± SD	8.5 ± 9.5	9.2 ± 9.6
Educational level
Second level, first stage (lower)	16 (17.4)	5 (10.4)
Second level, second stage (medium)	42 (45.7)	22 (45.8)
Third level (university)	34 (37.0)	21 (43.8)
UC extension
Proctitis	27 (29.3)
Left-sided colitis	23 (25.0)
Extensive colitis	42 (45.7)
CD extension
L1 terminal ileum		11 (22.9)
L2 colon		17 (35.4)
L3 ileocolon		18 (37.6)
L4 upper GI		2 (4.1)
Perceived IBD symptom score
No symptoms	23 (25.0)	9 (18.8)
Mild symptoms	41 (44.6)	22 (45.8)
Moderate symptoms	25 (27.2)	13 (27.1)
Severe symptoms	3 (3.2)	4 (8.3)

UC: Ulcerative colitis; CD: Crohn’s disease; IBD: Inflammatory bowel disease; GI: Gastrointestinal.

Table 3 Cohen`s d effect size calculated from crude dimensional rating form of inflammatory bowel disease patient concerns scores and presence of chronic fatigue

RFIPC factors	CD no CF	CD CF	P value	Cohen`s d	UC no CF	UC CF	P value	Cohen`s d
	(n = 34)	(n = 14)			(n = 72)	(n = 20)
Impact of disease	31.1 (20.6)	46.7 (17.7)	0.017	-0.81	25.6 (19.2)	45.7 (18.3)	< 0.001	-1.07
Expectancy	38.1 (30.5)	51.1 (23.1)	0.160	-0.48	32.6 (23.7)	55.3 (20.8)	< 0.001	-1.02
Treatment	27.5 (21.2)	38.0 (25.4)	0.146	-0.44	27.5 (22.0)	49.1 (22.5)	< 0.001	-0.97
Intimacy	20.3 (21.6)	28.3 (28.5)	0.299	-0.31	18.5 (18.9)	27.2 (20.1)	0.076	-0.44
Stigma	21.2 (24.3)	26.6 (20.2)	0.467	-0.24	17.3 (19.7)	35.0 (22.0)	0.001	-0.84
Complications	26.3 (23.6)	30.6 (18.6)	0.549	-0.20	21.2 (17.9)	35.7 (17.3)	0.002	-0.82
Sum score	29.2 (19.1)	39.6 (16.3)	0.082	-0.58	25.0 (15.9)	43.5 (14.5)	< 0.001	-1.21

Data are presented as mean (SD), calculated with independent samples t tests. RFIPC: Rating form of inflammatory bowel disease patient concerns; CD: Crohn’s disease; UC: Ulcerative colitis; CF: Chronic fatigue. Cohen`s d effect size: small, d = 0.2; medium, d = 0.5; large, d = 0.8.

Table 4 Univariate analysis of mean rating form of inflammatory bowel disease patient concerns scores in non-chronic fatigue and chronic fatigue patients

	Mean RFIPC adjusted for age, gender and education		Mean RFIPC adjusted for age, gender, education and IBD symptoms
	No CF mean	CF mean	No CF mean	CF mean
CD (n = 48)	(n = 34)	(n = 14)	(n = 34)	(n = 14)
Impact of disease	30.7	47.6a	32.2	44.0a
Expectancy	37.3	53.0	37.8	52.0
Treatment	27.5	38.0	27.2	39.0
Intimacy	19.7	30.0	20.6	27.8
Stigma	20.9	27.3	20.8	27.6
Complications	26.4	30.3	25.9	31.8
Sum score	28.8	40.3	29.4	39.0
UC (n = 92)	(n = 72)	(n = 20)	(n = 72)	(n = 20)
Impact of disease	25.7	45.3c	26.3	43.1c
Expectancy	33.0	53.8b	33.4	52.4c
Treatment	27.9	47.8c	28.5	45.6c
Intimacy	18.7	26.7	19.0	25.6a
Stigma	17.5	34.3b	17.9	33.1c
Complications	21.4	35.0b	21.7	34.0b
Sum score	25.2	42.8c	25.6	41.2c

RFIPC: Rating form of inflammatory bowel disease patient concerns; CD: Crohn’s disease; UC: Ulcerative colitis; CF: Chronic fatigue; IBD: Inflammatory bowel disease. Significance levels are between patients reporting CF or not:

^aP≤ 0.05,

^bP≤ 0.01,

^cP≤ 0.001.

Table 5 Correlation (Spearman’s ρ) between rating form of inflammatory bowel disease patient concerns sum, fatigue questionnaire sum, Norwegian inflammatory bowel disease questionnaire total and Short Form 36 dimensions

	CD (n = 48)	UC (n = 92)
	RFIPC sum score	RFIPC sum score
FQ
TF	0.36	0.49
N-IBDQ
IBDQ Total	-0.53	-0.51
SF-36
PF	-0.34	-0.40
RP	-0.28	-0.48
BP	-0.22	-0.44
GH	-0.49	-0.43
VT	-0.32	-0.48
SF	-0.40	-0.57
RE	-0.12	-0.49
MH	-0.31	-0.50

RFIPC: Rating form of inflammatory bowel disease patient concerns; CD: Crohn’s disease; UC: Ulcerative colitis; FQ: Fatigue questionnaire; TF: Total fatigue; N-IBDQ: Norwegian inflammatory bowel disease questionnaire; SF-36: Short Form 36; PF: Physical functioning; RP: Role physical; BP: Bodily pain; GH: General health; VT: Vitality; SF: Social functioning; RE: Role emotional; MH: Mental health.

Table 6 Linear regression analysιs of the rating form of inflammatory bowel disease patient concerns sum score, Norwegian inflammatory bowel disease questionnaire total score, total fatigue, chronic fatigue, Short Form 36 subdimensions and calculation of multicolinearity

Dependent		Independent	ß	P value	Tolerance	VIF
UC	RFIPC sum	N-IBDQ total	-0.70	< 0.001	0.24	4.1
	N-IBDQ total	RFIPC sum	0.29	< 0.001	0.58	1.7
		SF-36 BP	0.14	0.032	0.57	1.7
		SF-36 VT	0.17	0.019	0.50	2.0
		SF-36 SF	0.29	< 0.001	0.39	2.6
	TF	SF-36 VT	-0.25	0.031	0.49	2.0
	CF	RFIPC sum	0.34	0.018	0.46	2.2
CD	RFIPC sum	N-IBDQ total	-0.60	0.047	0.21	4.9
	N-IBDQ total	RFIPC sum	-0.17	0.047	0.71	1.4
		SF-36 SF	0.35	0.004	0.39	2.6
		SF-36 PF	0.22	0.033	0.49	2.0
		TF	-0.31	0.015	0.34	2.9

RFIPC: Rating form of inflammatory bowel disease patient concerns; CD: Crohn’s disease; UC: Ulcerative colitis; TF: Total fatigue; CF: Chronic fatigue; N-IBDQ: Norwegian inflammatory bowel disease questionnaire; SF-36: Short Form 36; PF: Physical functioning; BP: Bodily pain; VT: Vitality; SF: Social functioning; VIF: Variance inflation factor.