Psychometric performance of the CFQ-R-8D compared to the EQ-5D-3L and SF-6D in people with cystic fibrosis

Journal of Patient-Reported Outcomes

Table 2 Known-group validity based on clinical and demographic variables at baseline and follow-up for the SF-6D trial

		CFQ-R-8D				SF-6D				CFRSD
Variable	Groups	N	Mean	SD	ES^b	N	Mean	SD	ES^b	N	Mean	SD	ES^b
ppFEV₁—baseline	Normal ≥ 70%	111	0.833	0.10	0.27	111	0.822	0.12	0.18	111	32.31	12.39	−0.40
	Mild 40 to < 70%	284	0.801	0.12	0.49	284	0.801	0.12	0.34	284	36.92	10.62	−0.43
	Severe < 40%	45	0.743	0.12		45	0.761	0.12		45	41.84	11.18
			F(2,437) = 9.6				F(2,437) = 4.4				F(2,437) = 13.1
			P < 0.001				P = 0.013				P < 0.001
ppFEV₁—24 weeks^c	Normal ≥ 70%	110	0.843	0.11	0.27	110	0.834	0.12	0.19	110	29.68	13.70	−0.48
	Mild 40 to < 70%	251	0.809	0.12	0.44	251	0.81	0.12	0.35	251	35.82	11.44	−0.64
	Severe < 40%	45	0.754	0.15		45	0.766	0.13		45	43.96	11.67
			F(2,403) = 8.3				F(2,403) = 5.0				F(2,403) = 23.5
			P < 0.001				P = 0.007				P < 0.001
Pulmonary exacerbations—20–24 weeks (≥ 4)^c	No	368	0.822	0.12	0.70	368	0.822	0.12	0.68	368	34.27	12.79	−0.50
	Yes	48	0.733	0.13		48	0.736	0.12		48	40.79	12.78
			t(414) = 4.6				t(414) = 4.5				t(414) = −3.3
			P < 0.001				P < 0.001				P = 0.001
Age groups—baseline	14 to < 18 years	66	0.842	0.10	0.39	66	0.839	0.11	0.36	66	28.14	12.42	−0.84
	≥ 18 years	375	0.796	0.12		375	0.796	0.12		375	37.69	10.65
			t(439) = 2.9				t(439) = 2.8				t(439) = −6.7
			P = 0.004				P = 0.006				P < 0.001

CFQ-R-8D indicates Cystic Fibrosis Questionnaire–Revised–8 Dimensions; CFRSD: Cystic Fibrosis Respiratory Symptom Diary; ES: effect sizes; ppFEV1: percent predicted forced expiratory volume in 1 second; SF-6D: Short Form 6 dimensions
^aPooled treatment and placebo arms
^bES was calculated by comparing the utility values for adjacent sub-groups in the clinical measures. Small ES ≥0.2 to <0.5; medium ES ≥0.5 to <0.8; large ES ≥0.8
^c20-24 weeks and 24 weeks indicate follow-up at 20 to 24 weeks and follow-up at 24 weeks, respectively