We hypothesized that ankle-brachial index (ABI) increased with age as a result of arterial stiffness, and decreased when flow-limiting atherosclerotic stenosis occurred in the lower limbs. As arterial stiffness is associated with proteinuria, we investigated the relationship between ABI and prevalence of proteinuria.
A cross-sectional study of ABI and proteinuria with 13 193 participants aged 21–89 years (53% women) from health checkups between July 2003 and March 2010 was conducted. ABI was measured using the automatic oscillometric method, and stratified into four groups: ABI ≤0.9 (low); 0.9< ABI <1.0 (borderline low); 1.0≤ ABI <1.2 (normal); and 1.2≤ ABI <1.4 (high normal).
In participants with ABI at least 1.0, ABI was positively correlated with SBP, pulse pressure, and brachial-ankle pulse wave velocity. In participants with ABI less than 1.0, all indices were negatively correlated with ABI. The prevalence of proteinuria, defined as ≥1+ by dipstick, was significantly higher in low (23%) and high normal ABI (10%) compared with borderline low (6%) and normal ABI (7%). In participants at least 60 years, proteinuria was significantly associated with only low ABI [odds ratio (OR) 3.22, 95% confidence interval 1.34–7.41] compared with normal ABI before and after multivariable adjustment. In participants less than 60 years, adjusted OR for proteinuria was only significantly associated with high normal ABI (OR 1.32, 95% confidence interval 1.01–1.74).
High normal ABI in younger participants may be a result of arterial stiffness and associated with proteinuria.
aFaculty of Medicine, Department of Cardiovascular Medicine, Nephrology, and Neurology, University of the Ryukyus
bOkinawa General Health Maintenance Association
cDialysis Unit, University Hospital of the Ryukyus, Okinawa, Japan
Correspondence to Dr Akio Ishida, Faculty of Medicine, Department of Cardiovascular Medicine, Nephrology and Neurology, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa 903-0215, Japan. Tel: +81 98 895 1150; fax: +81 98 895 1416; e-mail: email@example.com
Abbreviations: ABI, ankle-brachial index; baPWV, brachial-ankle pulse wave velocity; eGFR, estimated glomerular filtration rate; LEAD, lower extremity artery disease; MBP, mean blood pressure; PP, pulse pressure
Received 30 August, 2013
Revised 16 January, 2014
Accepted 5 March, 2014