Relationship between 24 h ambulatory blood pressure and severity of white matter hyperintensities

Abstract

Objective To investigate the correlation between 24 h ambulatory blood pressure monitoring (ABPM) parameters and white matter hyperintensities (WMHs). Methods A cross-sectional analysis was performed in patients who visited the Department of Neurology, Liaoning People's Hospital, and showed WMHs on the head MRI and completed 24 h ABPM in the same period of hospitalization from September 2016 to October 2018. Periventricular white matter hyperintensities (PVWMHs) and deep white matter hyperintensities (DWMHs) were evaluated using the modified Scheltens scale respectively, and the sum of the two was used as the overall severity score of WMHs. The enrolled patients were grouped according to the tertiles of the overall WMH score. Multivariate ordinal logistic regression analysis was used to investigate independent risk factors affecting overall WMH scores. Multivariate linear regression analysis was used to investigate the influencing factors of PVWMH and DWMH scores. Results A total of 201 patients were enrolled, aged (62.7±10.3) years (range 45-88 years), 82 males (40.8%), and 123 patients (61.2%) with hypertension. The total WMH scores were 1-27. According to the tertiles, 64 patients (31.8%) were divided into lower tertile group (1-3), 65 (32.3%) in the middle tertile group (4-8), and 72 (35.8%) in the higher tertile group (9-27). There was significant difference in age between any two WMH score groups, namely, the high tertile group > middle tertile group > low tertile group (69.5±8.5 years vs. 63.1±9.2 years vs. 54.5±6.9 years; all P<0.001). The proportion of hypertension in the middle tertile group (66.2%) and the higher tertile group (69.4%) were significantly higher than those in the lower tertile group (46.9%; all P<0.05). The homocysteine in the higher tertile group was significantly higher than that in the lower tertile group (15.6[12.7-19.7]μmol/L vs. 14.1[12.5-15.9]μmol/L; P<0.05). In terms of 24 h ABPM parameters, the 24 h mean systolic blood pressure (24 h SBP) in the higher tertile group was higher than that in the lower tertile group, and the nighttime mean systolic blood pressure (nSBP) level in the higher tertile group was higher than that in the lower and middle tertile groups, the SD of daytime systolic blood pressure (dSBPSD) and the SD of the nighttime systolic blood pressure (nSBPSD) in the higher tertile group were higher than those in the lower tertile group, and dSBPSD of the middle tertile group was higher than of the lower tertile group. The above differences were statistically significant (all P<0.05). Multivariate ordinal logistic regression analysis showed that the increased age (odds ratio[OR]1.143, 95% confidence interval[CI]1.104-1.185; P<0.001), 24 h SBP (OR 1.026, 95% CI 1.005-1.048; P=0.015), dSBP (OR 1.022, 95% CI 1.001-1.043; P=0.036), nSBP (OR 1.026, 95% CI 1.006-1.046; P=0.011), dSBPSD (OR 1.119, 95% CI 1.023-1.221; P=0.013), and nSBPSD (OR 1.107, 95% CI 1.022-1.200; P=0.013) were independently positively correlated with the overall WMH score. Multivariate linear regression showed that age (β=0.607, 95% CI 0.500-0.714; P<0.001), 24 h SBP (β=0.182, 95% CI 0.075-0.289; P=0.001), dSBP (β=0.156, 95% CI 0.049-0.264; P=0.004), and nSBP (β=0.200, 95% CI 0.092-0.307; P<0.001) were independently positively correlated with the PVWMH score; age (β=0.505, 95% CI 0.387-0.622; P<0.001), 24 h SBP (β=0.132, 95% CI 0.015-0.248; P=0.027), dSBP (β=0.127, 95% CI 0.011-0.243; P=0.032), nSBP (β=0.148, 95% CI 0.031-0.265; P=0.013), and nSBPSD (β=0.133, 95% CI 0.016-0.250; P=0.027) were independently positively correlated with the DWMH score. Conclusion The increased age, ambulatory systolic blood pressure level (24 h, daytime, nighttime) and systolic blood pressure variability level (dSBPSD and nSBPSD) were independently associated with the severity of WMHs. Key words: Leukoaraiosis; Hypertension; Blood pressure; Blood pressure monitoring, portable; Cerebral small vessel diseases; White matter; Severity of illness index; Magnetic resonance imaging; Risk factors