Assessing the empirical validity of alternative multi-attribute utility measures in the maternity context

Table 4 Efficiency of multi-attribute utility measures to detect differences in self-reported health status; all women (n = 493)

Measure	Categorisation of self-reported health status	Utility score		t-test^a		Relative efficiency^b	ROC curve
		Mean	(SD)	t-statistic	p-value		Area^c	95% CI
EQ-5D	Excellent	0.964	(0.085)	9.334	<0.001	1.000	0.721*	(0.666, 0.776)
	Very good, good, fair or poor	0.837	(0.189)
SF-6D	Excellent	0.916	(0.091)	10.604	<0.001	1.291	0.798*	(0.748, 0.849)
	Very good, good, fair or poor	0.784	(0.138)
EQ-5D	Excellent or very good	0.925	(0.119)	9.156	<0.001	1.000	0.756*	(0.709, 0.802)
	Good, fair or poor	0.765	(0.213)
SF-6D	Excellent or very good	0.874	(0.108)	14.205	<0.001	2.407	0.841*	(0.804, 0.877)
	Good, fair or poor	0.712	(0.125)
EQ-5D	Excellent, very good or good	0.890	(0.145)	7.222	<0.001	1.000	0.849*	(0.790, 0.908)
	Fair or poor	0.616	(0.258)
SF-6D	Excellent, very good or good	0.830	(0.127)	10.742	<0.001	2.212	0.852*	(0.800, 0.905)
	Fair or poor	0.634	(0.119)
EQ-5D	Excellent, very good, good or fair	0.867	(0.169)	3.469	0.018	1.000	0.814*	(0.633, 0.996)
	Poor	0.366	(0.353)
SF-6D	Excellent, very good, good or fair	0.813	(0.136)	7.938	<0.001	5.236	0.847*	(0.686, 1.000)
	Poor	0.507	(0.093)

SD denotes standard deviation. ROC denotes receiver operating characteristic. CI denotes confidence interval.
^a Not assuming equality of variance as Levene test showed statistically significant differences in variances between self-reported health status groups.
^b Relative efficiency statistic is referenced to 1.0 for the EQ-5D measure. A value higher than 1.0 indicates that the SF-6D is more efficient than the EQ-5D in detecting differences between women in terms of their self-reported health status.
^c Area under receiver operating characteristic (ROC) curves; * p < 0.05 indicates that area under the ROC curve was statistically significantly greater than 0.5 and that measure has discriminatory power.