title: Mediating effects of nocturnal blood pressure and morning surge on the contributions of arterial stiffness and sodium intake to morning blood pressure: A path analysis.
abstract: BACKGROUND
  The aim of this study was to evaluate the mediating effects of nocturnal blood pressure (BP) and morning surge on the contribution of arterial stiffness and sodium intake to morning BP in a middle-aged general population.
  
  
  METHODS
  The study included 124 subjects aged 30-59 years, from rural Yeoju County, Gyeonggi Province, South Korea. Ambulatory BP monitoring, 24 h urinary sodium excretion (24 h UNa) and brachial-ankle pulse wave velocity (baPWV) measurements were performed in all subjects.
  
  
  RESULTS
  The mean ± SD age was 48.1 ± 8.2 years and the proportion of male subjects was 41.1%. After adjusting for covariates, morning systolic blood pressure (SBP) was significantly correlated with morning surge [coefficient = 0.761, 95% confidence interval (CI) 0.651-0.872, p < 0.001], nocturnal SBP (coefficient = 0.576, 95% CI 0.454-0.698, p < 0.001) and baPWV (coefficient = 3.550, 95% CI 1.447-5.653, p = 0.001). Path analysis modeling revealed that baPWV had significant direct (0.035, p = 0.013) and indirect effects (0.042, p = 0.012) on morning SBP. The indirect effect mediated by nocturnal SBP was statistically significant (0.054, p = 0.005), but the indirect effect mediated by the morning surge was not significant. The 24 h UNa had no significant direct or indirect effects on morning SBP.
  
  
  CONCLUSIONS
  baPWV had significant direct and indirect effects on morning SBP. The indirect effect was mediated by nocturnal SBP, but not by morning surge. The 24 h UNa had neither significant direct nor indirect effects on morning SBP.
authors.affiliation: a Departments of Internal Medicine , Hanyang University, College of Medicine , Seoul , Republic of Korea.
authors.forename: Hyung Tak
authors.initials: HT
authors.lastname: Lee
authors.affiliation: a Departments of Internal Medicine , Hanyang University, College of Medicine , Seoul , Republic of Korea.
authors.forename: Jin-Kyu
authors.initials: JK
authors.lastname: Park
authors.affiliation: b Departments of Preventive Medicine , Hanyang University, College of Medicine , Seoul , Republic of Korea.
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Choi
authors.affiliation: b Departments of Preventive Medicine , Hanyang University, College of Medicine , Seoul , Republic of Korea.
authors.forename: Bo Youl
authors.initials: BY
authors.lastname: Choi
authors.affiliation: b Departments of Preventive Medicine , Hanyang University, College of Medicine , Seoul , Republic of Korea.
authors.forename: Mi Kyung
authors.initials: MK
authors.lastname: Kim
authors.affiliation: c Institute for World Health Development, Mukogawa Women's University , Hyogo , Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Mori
authors.affiliation: c Institute for World Health Development, Mukogawa Women's University , Hyogo , Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamori
authors.affiliation: a Departments of Internal Medicine , Hanyang University, College of Medicine , Seoul , Republic of Korea.
authors.forename: Young Hyo
authors.initials: YH
authors.lastname: Lim
authors.affiliation: a Departments of Internal Medicine , Hanyang University, College of Medicine , Seoul , Republic of Korea.
authors.forename: Jinho
authors.initials: J
authors.lastname: Shin
mesh_terms: D000328:Adult; D055109:Ankle Brachial Index; D001783:Blood Flow Velocity; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology* / Q000652:urine; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D063177:Pulse Wave Analysis; D056910:Republic of Korea; D012424:Rural Population; D012982:Sodium, Dietary / Q000008:administration & dosage* / Q000652:urine; D059289:Vascular Stiffness
chemical_list: D012982:Sodium, Dietary
keywords: Ambulatory blood pressure; arterial stiffness; morning blood pressure; morning blood pressure surge; nocturnal blood pressure; urinary sodium excretion