Blood pressure and decline in kidney function in patients with atherosclerotic vascular disease: a cohort study.

BACKGROUND: Increased blood pressure generally is associated with kidney function decrease. We evaluated the rate of kidney function decrease, the effect of blood pressure on kidney function deterioration, and the possible interaction with albuminuria in patients with vascular disease.

STUDY DESIGN: Prospective cohort study.

SETTING & PARTICIPANTS: 745 patients with vascular disease from the Second Manifestations of Arterial Disease (SMART) Study.

FACTORS: Blood pressure, hypertension presence, albuminuria (albumin-creatinine ratio > 27 mg/g).

OUTCOMES: Rate of kidney function decrease, calculated from the difference between 2 estimated glomerular filtration rate (eGFR) values divided by the individual follow-up time.

MEASUREMENTS: Participants underwent vascular screening at baseline and after a mean follow-up of 4.5 +/- 1.0 years. Rate of kidney function decrease was expressed as annual decrease in eGFR. Linear regression analysis was used to evaluate the relation between blood pressure and eGFR decrease.

RESULTS: Mean baseline eGFR was 79.3 +/- 16.3 mL/min/1.73 m(2), and mean annual decrease in eGFR was 1.00 +/- 2.71 mL/min/1.73 m(2). In 35% of patients, eGFR was stable during follow-up. Albuminuria was present in 100 patients (median albumin-creatinine ratio, 58 mg/g). In patients without albuminuria, age-, sex-, and baseline eGFR-adjusted annual eGFR decrease was 0.86 mL/min/1.73 m(2), whereas this was 1.89 mL/min/1.73 m(2) in patients with albuminuria (P < 0.05). In the presence of albuminuria, higher blood pressure was associated with greater eGFR decrease (beta = 1.29; 95% CI, 0.73-1.85 for systolic blood pressure and beta = 3.86; 95% CI, 2.34-5.38 for hypertension presence). In patients without albuminuria, no association was found between blood pressure and kidney function decrease (beta = 0.15; 95% CI, -0.05 to 0.36 for systolic blood pressure and beta = 0.12; 95% CI, -0.28 to 0.52 for hypertension presence; P for interaction term < 0.05).

LIMITATIONS: Participants might reflect a healthier subgroup of patients with vascular disease. Creatinine was measured only twice.

CONCLUSIONS: Kidney function decrease in patients with vascular disease is considerable. Blood pressure is a strong risk factor for eGFR decrease in patients with vascular disease and albuminuria.