Table 3. Linear regression analyses for factors associated with the log-transformed value of the white-matter hyperintensity volumes.

WMH total volume (%, log-transformed)a	B (95% CI)	β	P
Intercept	-8.135 (-10.815–-5.456)		<0.001**
Age (year)	0.032 (0.018–0.046)	0.415	<0.001**
Apnea-hypopnea index (/h)	0.008 (0.001–0.016)	0.191	0.020*
MCA PI	1.001 (0.011–1.990)	0.180	0.047*
MRIR	3.775 (1.232–6.318)	0.234	0.004**
WMH subcortical volume (%, log-transformed)b	B (95% CI)	β	P
Intercept	-7.977 (-10.528–-5.427)	0.000	<0.001**
Age (year)	0.026 (0.013–0.039)	0.356	<0.001**
Apnea-hypopnea index (/h)	0.015 (0.007–0.022)	0.336	<0.001**
MCA PI	1.002 (-0.017–2.021)	0.178	0.054
MRIR	3.964 (1.346–6.583)	0.243	0.013*
WMH periventricular volume (%, log-transformed)c	B (95% CI)	β	P
Intercept	-9.217 (-12.04–-6.394)	0.000	<0.001**
Age (year)	0.032 (0.018–0.046)	0.418	<0.001**
Oxygen desaturation index (/h)	0.006 (0.001–0.010)	0.192	0.046*
MCA PI	1.107 (0.005–2.210)	0.188	0.049*
MRIR	3.512 (1.220–5.803)	0.224	0.016**

^aR² = 0.424 and P<0.001,

^bR² = 0.676 and P<0.001, and

^cR² = 0.619 and P<0.001 for the linear regression equation.

B: unstandardized coefficient, β: standardized coefficient, CI: confidence interval, WMH: white matter hyperintensity, MCA: middle cerebral artery, PI: pulsatility index, and MRIR: mean middle cerebral artery resistance index ratio.

*P<0.05 and

**P<0.01.