The prognostic significance of abnormal circadian blood pressure (BP) patterns is well established. Research to date has focused on both nocturnal dipping and absolute night-time BP levels; however, which of these variables should be the primary target for therapy remains unclear. The aim of this study is to determine whether dipping status or absolute night-time BP levels have a stronger association with subclinical target organ damage (TOD).
The Mitchelstown Cohort was established to examine cardiovascular health in an adult population sample recruited from primary care. Night-time BP was categorized by dipping status. Subclinical TOD was defined as Cornell Product left ventricular hypertrophy (LVH) voltage criteria on ECG and urine albumin : creatinine ratio (ACR) at least 1.1 mg/mmol. Multivariable logistic regression analysis was used to assess the association between night-time BP and TOD.
Of 2047 participants, 1207 (response rate 59%), underwent 24-h ambulatory BP monitoring. We excluded 161 studies due to incomplete data. Of 1046 participants, 178 (17%) had evidence of TOD. Each 10-mmHg rise in night-time SBP increased the odds of TOD. Odds ratio (OR) ACR at least 1.1 mg/mmol 1.5 [95% confidence interval (95% CI) 1.2–1.8] and OR LVH 1.4 (95% CI 1.1–1.8).
Absolute BP level rather than dipping status may be a superior early marker of risk associated with night-time BP. Interventional studies are required to determine whether there is a benefit in specifically targeting absolute night-time BP levels to prevent clinically important outcomes.
aDepartment of Epidemiology and Public Health, University College Cork, Western Road, Cork
bDepartment of Geriatrics, Connolly Hospital, Blanchardstown, Dublin
cDepartment of Cardiology, Cork University Hospital, Wilton, Cork
dConway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
Correspondence to Dr Anne Marie O’Flynn, Department of Epidemiology and Public Health, 4th Floor, Western Gateway Building, University College Cork, Western Road, Cork, Ireland. Tel: +353 21 4205537; e-mail: firstname.lastname@example.org
Abbreviations: ABPM, ambulatory blood pressure monitoring; ACR, albumin creatinine ratio; ANOVA, analysis of variance; BP, blood pressure; CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; ECG, electrocardiogram; eGFR, estimated glomerular filtration rate; LVH, left ventricular hypertrophy; OR, odds ratio; TOD, target organ damage
Received 24 March, 2015
Revised 8 June, 2015
Accepted 8 June, 2015