Table 2.

Multivariate regression model for utility of patients with AD

Parameter	Beta coefficient (β)	Standard error	95% Wald confidence interval		Hypothesis test
			Lower	Upper	Wald chi-squared	Degrees of freedom (df)	Significance
(Intercept)	1.348	0.2433	0.871	1.825	30.675	1	0.000
Severity rank = 2	0.108	0.0256	0.058	0.158	17.746	1	0.000
Severity rank = 3	0.086	0.0504	−0.013	0.185	2.925	1	0.087
Severity rank = 4	0a
Age, years	−0.005	0.0031	−0.011	0.001	2.626	1	0.105
% of males	−0.863	0.2772	−1.406	−0.319	9.686	1	0.002
Scale	0.001b	0.0006	0.001	0.003

Dependent variable: quality of life

^aSet to zero because this parameter is redundant

^bMaximum-likelihood estimate