Can we derive an 'exchange rate' between descriptive and preference-based outcome measures for stroke? Results from the transfer to utility (TTU) technique

Table 2 Regression algorithms for converting SF-36 scores into AQoL scores

Model	Predictor	β	SE	t	Sig.
SF-36 Scale
All stroke	(Constant)	0.1148	0.139	0.82	0.411
	PCS	0.0024	0.003	0.67	0.503
	MCS	-0.0004	0.003	-0.14	0.885
	PCS*PCS				ns
	MCS*MCS				ns
	MCS*PCS	0.0001	0.000	2.23	0.027
		0.7056		F_639,431 = 2.85	0.000
		Obs^ = 1074	Ids^# = 640	F_3,431 = 37.01	0.000
			R² _within = 0.21	R² _between = 0.59	R² _overall = 0.55
SF-36 Subscale
All stroke	(Constant)	0.0986	0.314	3.15	0.002
	Physical Function (PF)	0.0057	0.001	4.46	0.000
	General Health (GH)	0.0017	0.001	3.11	0.002
	Mental Health (MH)*PF	3.84*10^-5	9.73*10^-6	3.95	0.000
	PF*PF	-5.35*10^-5	1.19*10^-5	-4.48	0.000
	PF* Role Physical (RP)	1.29*10^-5	6.11*10^-6	2.11	0.035
	Social Function (SF)*SF	8.47*10^-6	2.56*10^-6	3.31	0.001
	Bodily Pain (BP)*RP	8.65*10^-6	4.35*10^-6	1.99	0.047
	GH*RP	-2.10*10^-5	6.35*10^-6	-3.30	0.001
		0.6298		F_639,431 = 2.01	0.000
		Obs = 1079	Ids = 640	F_8,431 = 28.78	0.000
			R² _within = 0.35	R² _between = 0.75	R² _overall = 0.72
SF-36 Item
All stroke	(Constant)	-0.1986	0.0790	-2.51	0.012
	Item 1 (general health now)	-0.0197	0.0101	-1.94	0.053
	Item 3b (moderate activities)	0.0519	0.0151	3.44	0.001
	Item 3e (one flight stairs)	0.0353	0.0160	2.21	0.028
	Item 3h (walking 1/2 km)	0.0345	0.0155	2.22	0.027
	Item 3j (bathing/dressing)	0.0768	0.0173	4.43	0.000
	Item 4a (other activities)	0.0279	0.0168	1.67	0.096
	Item 9b (nervous)	0.0157	0.0066	2.37	0.018
	Item 9f (felt down)	0.0132	0.0075	1.74	0.082
	Item 9i (tired)	0.0199	0.0065	3.04	0.002
	Item 10 (social activities, time)	0.0147	0.0064	2.31	0.021
		0.6294		F_640,429 = 1.85	0.000
		Obs = 1080	Ids = 641	F_10,429 = 21.87	0.000
			R² _within = 0.34	R² _between = 0.73	R² _overall = 0.71

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