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Association between high nocturnal blood pressure and white matter change and its interaction by obstructive sleep apnoea among normotensive adults

Lee, Sungheea; Thomas, Robert Josephb; Kim, Hyuna; Seo, Hyung Sukc; Baik, Inkyungd; Yoon, Dae Wuia; Kim, Se Joonge; Lee, Seung Kua; Shin, Chola,f

doi: 10.1097/HJH.0000000000000290
ORIGINAL PAPERS: Blood pressure measurement

Objectives: A reverse dipping pattern, characterized by higher night-time blood pressure (BP) than daytime BP, is associated with the increased risk for cerebrovascular disease, cardiovascular events and all-cause mortality. However, little has known about the association between white matter change (WMC) and reverse dipping pattern, particularly in normotensive adults. We aimed to examine whether WMC is associated with BP dipping patterns as measured with a 24-h ambulatory BP monitoring and whether obstructive sleep apnoea (OSA) is involved in this relationship

Methods: A total of 703 normotensive adults were from an ongoing longitudinal study in a general population. WMC was measured with brain MRI. BP dipping patterns were defined as the ratio of the change in night-time and daytime SBP. OSA was categorized with the apnoea-hypopnea index, as measured with polysomnography. To avoid the influence of hypertensive medications, we only included normotensive adults for the final analysis. To examine the associations between WMC and dipping patterns, we built logistic models. To elucidate the role of OSA, we also conducted both modification and mediation tests.

Results: Reverse dipping pattern was significantly associated with WMC (odds ratio 1.49, 95% confidence interval 1.02–2.18). Further, OSA modified the association between dipping patterns and WMC (P = 0.0118). No mediation effect of OSA was assessed.

Conclusion: In 703 normotensive adults, the reverse dipping pattern showed a significant association with WMC, after adjusting for covariates. Further, according to the presence of OSA, the association between reverse dipping and WMC was varied.

aInstitute of Human Genomic Study, School of Medicine, Korea University Ansan Hospital, Ansan, Republic of Korea

bDepartment of Medicine, Division of Pulmonary, Critical care & Sleep, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA

cDepartment of Radiology, School of Medicine, Korea University, Ansan Hospital, Ansan

dDepartment of Foods and Nutrition, College of Natural Sciences, Kookmin University, Seoul

eDivision of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam

fDivision of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University, Ansan Hospital, Ansan, Republic of Korea

Correspondence to Chol Shin, MD, PhD, Division of Respiratory and Critical Care, Department of Internal Medicine, Ansan Hospital, Korea University, 516 Gojan-1-dong, Danwon-gu, Ansan-si, Gyeonggi-do 425-707, South Korea. Tel: +82 31 412 5603; fax: +82 31 412 5604; e-mail: chol-shin@korea.ac.kr

Abbreviations: ABPM, ambulatory blood pressure monitoring; AHI, apnoea-hypopnea index; BP, blood pressure; OSA, obstructive sleep apnoea; WMC, white matter change

Received 4 February, 2014

Revised 28 May, 2014

Accepted 28 May, 2014

© 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins