Table 4.

Linear regression analyses for factors associated with white matter hyperintensity severity.

Total WMH†a	B (95% CI)	β	P
Constant variable	1.289 (−2.267–4.844)		0.458
Age	0.092 (0.033–0.151)	0.543	0.004*
Sleep/waking ratio of the VLF peak†	−0.517 (−0.915–−0.120)	−0.455	0.013*
Subcortical WMH †b
Constant variable	2.524 (−2.131–7.178)		0.271
Age	0.049 (−0.028–0.127)	0.244	0.198
Sleep/waking ratio of the VLF peak†	−0.630 (−1.150–−0.109)	−0.465	0.020*
Periventricular WMH †c
Constant variable	−0.335 (−4.807–4.137)		0.877
Age	0.106 (0.035–0.177)	0.571	0.006*
Sleep/waking ratio of the VLF peak†	−0.134 (−0.346–0.077)	−0.243	0.201
Waking PI	1.701 (−1.338–4.740)	0.210	0.257

^aR² = 0.497 and P = 0.003, ^bR² = 0.391 and P = 0.017, and ^cR² = 0.369 and P = 0.024 for the linear regression equations.

^†The variables were log transformed to obtain a normal distribution. B, unstandardized coefficient and β, standardized coefficient. ^*P < 0.05, ^**P < 0.01.