Functional Assessment of Chronic Illness Therapy-Fatigue is a reliable and valid measure in patients with active ankylosing spondylitis

Cella, David; Lenderking, William R.; Chongpinitchai, Peter; Bushmakin, Andrew G.; Dina, Oluwaseyi; Wang, Lisy; Cappelleri, Joseph C.; Navarro-Compán, Victoria

doi:10.1186/s41687-022-00508-0

Journal of Patient-Reported Outcomes

Table 2 Correlations to assess the convergent validity of FACIT-F versus other PRO measures in patients with active AS

From: Functional Assessment of Chronic Illness Therapy-Fatigue is a reliable and valid measure in patients with active ankylosing spondylitis

	Study 1*		Study 2^†
	Baseline	Week 12	Baseline	Week 16
Correlations with FACIT-F Experience domain
PtGA	− 0.48	− 0.39	− 0.40	− 0.53
Total back pain due to AS	− 0.49	− 0.46	− 0.36	− 0.54
Nocturnal spinal pain due to AS	− 0.45	− 0.49	− 0.30	− 0.52
SF-36v2 Physical Functioning	0.59	0.57	0.53	0.60
SF-36v2 Role-Physical	0.57	0.68	0.58	0.70
SF-36v2 Bodily Pain	0.57	0.62	0.50	0.69
SF-36v2 General Health	0.51	0.59	0.51	0.63
SF-36v2 Vitality	0.77	0.85	0.75	0.85
SF-36v2 Social Functioning	0.63	0.69	0.62	0.72
SF-36v2 Role-Emotional	0.46	0.62	0.50	0.66
SF-36v2 Mental Health	0.60	0.71	0.64	0.72
SF-36v2 PCS	0.56	0.60	0.44	0.62
SF-36v2 MCS	0.61	0.74	0.64	0.76
BASFI	− 0.49	− 0.52	− 0.44	− 0.56
BASDAI	− 0.59	− 0.60	− 0.49	− 0.62
EQ-5D Utility Index	0.48	0.51	0.52	0.59
ASQoL	− 0.72	− 0.75	− 0.66	− 0.74
Correlations with FACIT-F Impact domain
PtGA	− 0.46	− 0.46	− 0.39	− 0.45
Total back pain due to AS	− 0.55	− 0.55	− 0.38	− 0.50
Nocturnal spinal pain due to AS	− 0.43	− 0.57	− 0.37	− 0.51
SF-36v2 Physical Functioning	0.72	0.67	0.63	0.64
SF-36v2 Role-Physical	0.69	0.75	0.63	0.71
SF-36v2 Bodily Pain	0.62	0.64	0.54	0.68
SF-36v2 General Health	0.50	0.55	0.51	0.53
SF-36v2 Vitality	0.70	0.75	0.62	0.71
SF-36v2 Social Functioning	0.72	0.76	0.71	0.74
SF-36v2 Role-Emotional	0.60	0.73	0.56	0.66
SF-36v2 Mental Health	0.62	0.71	0.65	0.70
SF-36v2 PCS	0.64	0.64	0.50	0.61
SF-36v2 MCS	0.65	0.75	0.65	0.72
BASFI	− 0.61	− 0.62	− 0.56	− 0.60
BASDAI	− 0.59	− 0.66	− 0.52	− 0.58
EQ-5D Utility Index	0.58	0.61	0.56	0.63
ASQoL	− 0.80	− 0.82	− 0.76	− 0.78
Correlations with FACIT-F total score
PtGA	− 0.49	− 0.45	− 0.41	− 0.51
Total back pain due to AS	− 0.55	− 0.54	− 0.39	− 0.54
Nocturnal spinal pain due to AS	− 0.46	− 0.56	− 0.36	− 0.54
SF-36v2 Physical Functioning	0.70	0.66	0.62	0.65
SF-36v2 Role-Physical	0.67	0.75	0.64	0.74
SF-36v2 Bodily Pain	0.63	0.66	0.55	0.72
SF-36v2 General Health	0.53	0.59	0.53	0.60
SF-36v2 Vitality	0.76	0.82	0.71	0.80
SF-36v2 Social Functioning	0.72	0.76	0.71	0.76
SF-36v2 Role-Emotional	0.57	0.71	0.57	0.69
SF-36v2 Mental Health	0.65	0.74	0.68	0.74
SF-36v2 PCS	0.64	0.65	0.51	0.65
SF-36v2 MCS	0.67	0.78	0.68	0.77
BASFI	− 0.59	− 0.60	− 0.54	− 0.61
BASDAI	− 0.62	− 0.66	− 0.53	− 0.63
EQ-5D Utility Index	0.57	0.59	0.57	0.64
ASQoL	− 0.80	− 0.82	− 0.76	− 0.80

Correlations between 0.4–0.8 were considered to be indicative of convergent validity
All correlations were statistically significant (p < 0.0001)
AS, ankylosing spondylitis; ASQoL, Ankylosing Spondylitis Quality of Life; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; EQ-5D, EuroQol-5 Dimension; FACIT-F, Functional Assessment of Chronic Illness Therapy-Fatigue; MCS, Mental Component Summary; PCS, Physical Component Summary; PRO, patient-reported outcome; PtGA, Patient Global Assessment of Disease Activity; SF-36v2, Short Form-36 Health Survey version 2
*NCT01786668 (phase 2 study)
^†NCT03502616 (phase 3 study)

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