Ankle-Brachial Index Predicts Early Stage CKD
VANCOUVER, B.C.—The ankle-brachial index (ABI) is a good predictor of stage 1 chronic kidney disease (CKD) among patients with hypertension, researchers reported at the World Congress of Nephrology.
A team at the Federal University of Ceara in Fortaleza, Brazil, prospectively studied 225 hypertensive patients who had an average age of 63 years. The study population was 74.7% female. The investigators, led by Ricardo Pereira Silva, MD, measured each patient's ABI two times during a medical visit and calculated a mean value. They considered an ABI below 0.9 to be abnormal. The researchers estimated patients' glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease study formula.
The researchers identified an abnormal ABI in 61 patients (27.1%). Sixty-seven patients (29.7%) had diabetes mellitus. An abnormal ABI was significantly more common in patients with diabetes than those without the disease (31% vs. 19%).
Dr. Silva's group identified CKD in 153 patients (72.8%). In this group, CKD stages 1, 2, 3, 4, and 5 were present in 27.5%, 59.2%, 12.3%, 0.5%, and 0.5% of subjects, respectively. CKD was present in 90.3% of those with an abnormal ABI and 77.1% of those with a normal ABI, a significant difference between the groups. Patients with an abnormal ABI had a significantly higher frequency of CKD stage I (33.8% vs. 18.4%), but abnormal ABI was not associated with CKD stages 2-5.
Additionally, the frequency of CKD increased according ABI values. The researchers found CKD in 57.3%, 60%, 70%, 50%, and 100% of patients with an ABI below 0.9, 0.8, 0.7, 0.6, and 0.5, respectively.
ABI determination is an easy and inexpensive way to identify arterial disease, so it may be determined for all hypertensive patients, Dr. Silva said. In addition, CKD occurs frequently among hypertensive patients. “So, we have an easy and cheap method that can predict early stage CKD among hypertensive patients,” Dr. Silva said.