Mapping the EQ-5D index from the cystic fibrosis questionnaire-revised using multiple modelling approaches

Table 4 Summary of observed and predicted values by EQ-5D group and FEV ₁ severity

Observed EQ-5D range	N	Observed EQ-5D	OLS models		Tobit models		TPM models
Observed EQ-5D range	N	Observed EQ-5D	Domain (3)	Item (5)	Domain (3)	Item (5)	Domain (3)	Item (8)
−0.349 - 0.099	23	−0.028	0.294 (0.321)	0.197 (0.225)	0.293 (0.320)	0.185 (0.214)	0.274 (0.307)	0.160 (0.196)
0.1 - 0.299	41	0.227	0.420 (0.211)	0.337 (0.149)	0.421 (0.209)	0.335 (0.148)	0.418 (0.214)	0.320 (0.134)
0.3 - 0.599	38	0.511	0.505 (0.130)	0.518 (0.106)	0.502 (0.136)	0.517 (0.113)	0.524 (0.135)	0.532 (0.100)
0.6 - 0.699	92	0.660	0.620 (0.106)	0.643 (0.093)	0.621 (0.110)	0.643 (0.098)	0.649 (0.115)	0.655 (0.092)
0.7 - 0.799	71	0.756	0.747 (0.084)	0.736 (0.088)	0.749 (0.093)	0.737 (0.097)	0.778 (0.099)	0.761 (0.089)
0.8 - 0.899	59	0.841	0.794 (0.109)	0.804 (0.097)	0.792 (0.103)	0.804 (0.100)	0.817 (0.101)	0.816 (0.099)
0.9 - 1	77	1	0.895 (0.107)	0.938 (0.088)	0.900 (0.100)	0.949 (0.051)	0.916 (0.084)	0.948 (0.052)
ANOVA			F = 107.30	F = 176.10	F = 105.70	F = 183.84	F =104.81	F = 202.73
ANOVA			p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001
FEV ₁
Severe < 41%	92	0.552	0.550 (0.157)	0.548 (0.132)	0.548 (0.158)	0.550 (0.133)	0.565 (0.157)	0.561 (0.121)
Moderate 41-70%	136	0.695	0.684 (0.119)	0.694 (0.107)	0.683 (0.120)	0.693 (0.101)	0.703 (0.120)	0.702 (0.099)
Mild > 70%	105	0.741	0.755 (0.113)	0.748 (0.097)	0.760 (0.116)	0.751 (0.090)	0.781 (0.111)	0.757 (0.076)
ANOVA			F = 24.38	F = 19.29	25.39	F = 18.43	F = 23.83	F = 16.76
ANOVA			p< 0.001	p< 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001

OLS, ordinary least squares; TPM, two-part model; FEV₁, percentage of predicted Forced Expiratory Volume in 1 second.
Model 3 = CFQ-R domains that are statistically significant at the 10% level + statistically significant squared terms; Model 5 = All CFQ-R items excluding the health domain items; TPM Model 8 = All CFQ-R items excluding the health domain items + age and gender.

ISSN: 1477-7525