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

Table 7 Post-sample predictive validity for NIHSS 'all stroke' & 'severity-specific' algorithms

Data	Model	Group	N	Min	Max	Mean	SD
Observed AQoL	Validation sample	NIHSS = 0	819	-0.04	1.00	0.546	0.334
		NIHSS = 1–5	312	-0.03	1.00	0.443	0.294
		NIHSS ≥ 6	132	-0.04	0.98	0.112	0.210
All stroke algorithm
Predicted AQoL	Index-based	NIHSS = 0	819	0.45	0.45	0.453	0.000
		NIHSS = 1–5	312	0.46	0.48	0.466	0.007
		NIHSS ≥ 6	132	0.49	0.57	0.504	0.020
	Item-based	NIHSS = 0	819	0.44	0.44	0.443	0.000
		NIHSS = 1–5	312	0.22	0.47	0.435	0.042
		NIHSS ≥ 6	132	0.22	0.47	0.428	0.061
Mean Absolute Deviation (MAD)	Index-based	NIHSS = 0	819	0.00	0.55	0.309	0.156
		NIHSS = 1–5	312	0.00	0.54	0.258	0.147
		NIHSS ≥ 6	132	0.02	0.60	0.431	0.124
	Item-based	NIHSS = 0	819	0.00	0.56	0.312	0.157
		NIHSS = 1–5	312	0.00	0.65	0.251	0.148
		NIHSS ≥ 6	132	0.04	0.65	0.114	0.359
Severity algorithms
Predicted AQoL	Index-based	NIHSS = 0*	819	0.48	0.48	0.475	0.000
		NIHSS = 1–5*	312	0.45	0.57	0.539	0.033
		NIHSS ≥ 6^	132	-0.02	0.16	0.099	0.054
	Item-based	NIHSS = 0*	819	0.46	0.46	0.461	0.000
		NIHSS = 1–5*	312	0.46	0.65	0.486	0.032
		NIHSS ≥ 6^	132	-0.08	0.20	0.096	0.046
Mean Absolute Deviation (MAD)	Index-based	NIHSS = 0*	819	0.00	0.52	0.304	0.155
		NIHSS = 1–5*	312	0.00	0.58	0.262	0.160
		NIHSS ≥ 6^	132	0.00	0.82	0.120	0.157
	Item-based	NIHSS = 0*	819	0.00	0.54	0.307	0.155
		NIHSS = 1–5*	312	0.00	0.55	0.259	0.146
		NIHSS ≥ 6^	132	0.00	0.65	0.302	0.154

*Predicted values obtained from 'low severity' algorithm. ^Predicted values obtained from 'moderate to severe severity' algorithm.

ISSN: 1477-7525