Clinical Prediction of Functional Outcome after Ischemic Stroke: The Surprising Importance of Periventricular White Matter Disease and Race

Brett Kissela; Christopher J. Lindsell; Dawn Kleindorfer; Kathleen Alwell; Charles J. Moomaw; Daniel Woo; Matthew L. Flaherty; Ellen Air; Joseph Broderick; Joel Tsevat

doi:10.1161/STROKEAHA.108.521906

Table D

Factors influencing 3 month outcomes. Each stage of the modeling process is shown. The variable removed at each step is indicated by an asterisk (*).

		β	95% CI ( β )	P-value	R²
Initial model (maximum correlation coefficient −0.412)
n=305	Age	0.01	(0.00 – 0.02)	0.047	0.486
	Partnered	−0.04	(−0.30 – 0.22)	0.747
	Smoker	−0.17	(−0.44 – 0.10)	0.222
	Diabetes	0.22	(−0.04 – 0.48)	0.101
	Prior stroke*	−0.03	(−0.31 – 0.26)	0.862
	Severe PVWMD	0.49	(0.07 – 0.91)	0.021
	Pre-stroke Rankin	0.22	(0.13 – 0.31)	<0.001
	Post-stroke Rankin	0.54	(0.42 – 0.66)	<0.001
	Estimated NIHSS	0.04	(0.01 – 0.06)	0.010
	Thrombolytics	−0.34	(−0.86 – 0.19)	0.214

Step 2
n=305	Age	0.01	(0.00 – 0.02)	0.044	0.486
	Partnered*	−0.04	(−0.30 – 0.22)	0.752
	Smoker	−0.17	(−0.44 – 0.10)	0.215
	Diabetes	0.22	(−0.04 – 0.48)	0.103
	Severe PVWMD	0.49	(0.07 – 0.91)	0.021
	Pre-stroke Rankin	0.22	(0.13 – 0.30)	<0.001
	Post-stroke Rankin	0.53	(0.41 – 0.65)	<0.001
	Estimated NIHSS	0.04	(0.01 – 0.06)	0.010
	Thrombolytics	−0.33	(−0.86 – 0.19)	0.216

Step 3
n=331	Age	0.01	(0.00 – 0.02)	0.042	0.492
	Smoker*	−0.18	(−0.43 – 0.07)	0.160
	Diabetes	0.25	(0.01 – 0.49)	0.043
	Severe PVWMD	0.47	(0.07 – 0.87)	0.022
	Pre-stroke Rankin	0.19	(0.11 – 0.28)	<0.001
	Post-stroke Rankin	0.54	(0.43 – 0.65)	<0.001
	Estimated NIHSS	0.04	(0.01 – 0.06)	0.006
	Thrombolytics	−0.37	(−0.86 – 0.13)	0.144

Step 4
n=331	Age	0.01	(0.00 – 0.02)	0.015	0.489
	Diabetes	0.27	(0.02 – 0.51)	0.032
	Severe PVWMD	0.46	(0.06 – 0.86)	0.025
	Pre-stroke Rankin	0.20	(0.11 – 0.28)	<0.001
	Post-stroke Rankin	0.55	(0.43 – 0.66)	<0.001
	Estimated NIHSS	0.04	(0.01 – 0.06)	0.004
	Thrombolytics*	−0.40	(−0.89 – 0.10)	0.115

Final model
n=332	Age	0.01	(0.00 – 0.02)	0.008	0.484
	Diabetes	0.27	(0.02 – 0.51)	0.031
	Severe PVWMD	0.47	(0.07 – 0.87)	0.021
	Pre-stroke Rankin	0.20	(0.12 – 0.28)	<0.001
	Post-stroke Rankin	0.56	(0.46 – 0.67)	<0.001
	Estimated NIHSS	0.03	(0.00 – 0.05)	0.016

Note: repeating these analyses without imaging data (excluding pvwmd) results in the same final model and an R² of 0.485 – one might assume knowing pvwmd status on all cases would have improved this R²