Low ankle-brachial index and the development of rapid estimated GFR decline and CKD.

BACKGROUND

Low ankle-brachial index (ABI) is associated with increases in serum creatinine level. Whether low ABI is associated with the development of rapid estimated glomerular filtration rate (eGFR) decline, stage 3 chronic kidney disease (CKD), or microalbuminuria is uncertain.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS: Framingham Offspring cohort participants who attended the sixth (1995-1998) and eighth (2005-2008) examinations.

PREDICTOR

ABI, categorized as normal (>1.1 to <1.4), low-normal (>0.9 to 1.1), and low (≤0.9).

OUTCOMES

Rapid eGFR decline (eGFR decline ≥3 mL/min/1.73 m(2) per year), incident stage 3 CKD (eGFR <60 mL/min/1.73 m(2)), incident microalbuminuria.

MEASUREMENTS

GFR was estimated using the serum creatinine-based CKD-EPI (CKD Epidemiology Collaboration) equation. Urinary albumin-creatinine ratio (UACR) was determined based on spot urine samples.

RESULTS

During 9.5 years, 9.0% (232 of 2,592) experienced rapid eGFR decline and 11.1% (270 of 2,426) developed stage 3 CKD. Compared to normal ABI, low ABI was associated with 5.73-fold increased odds of rapid eGFR decline (95% CI, 2.77-11.85; P<0.001) after age, sex, and baseline eGFR adjustment; this persisted after multivariable adjustment for standard CKD risk factors (OR, 3.60; 95% CI, 1.65-7.87; P = 0.001). After adjustment for age, sex, and baseline eGFR, low ABI was associated with a 2.51-fold increased odds of stage 3 CKD (OR, 2.51; 95% CI, 1.16-5.44; P = 0.02), although this was attenuated after multivariable adjustment (OR, 1.68; 95% CI, 0.75-3.76; P = 0.2). In 1,902 free of baseline microalbuminuria, low ABI was associated with increased odds of microalbuminuria after adjustment for age, sex, and baseline UACR (OR, 2.81; 95% CI, 1.07-7.37; P = 0.04), with attenuation upon further adjustment (OR, 1.88; P = 0.1).

LIMITATIONS

Limited number of events with low ABI. Outcomes based on single serum creatinine and UACR measurements at each examination.

CONCLUSIONS

Low ABI is associated with an increased risk of rapid eGFR decline, suggesting that systemic atherosclerosis predicts a decrease in kidney function.