Creatinine clearance and signs of end-organ damage in primary hypertension

A reduction in renal function is associated with high cardiovascular morbidity and mortality in hypertension. The aim of the present study was to investigate the relationship between creatinine clearance and subclinical organ damage in 957 never previously treated, middle-aged patients with primary hypertension. Renal function was estimated by means of the serum creatinine level using the Cockcroft-Gault formula; left ventricular hypertrophy (LVH) was determined according to electrocardiographic criteria; and retinal vascular changes were evaluated by direct ophthalmoscopy. Creatinine clearance was, on the average, 83+/-21.2 ml/min, and the prevalence of LVH and retinopathy was 13 and 49%, respectively. Creatinine clearance was inversely related to the duration of disease (r=-0.132, P<0.0001), systolic blood pressure (r=-0.110, P=0.001), serum glucose (r=-0.090, P=0.007), total cholesterol (r=-0.196, P<0.0001), and LDL-cholesterol (r=-0.196, P<0.0001). Patients in the lower quintile of creatinine clearance showed a higher prevalence of electrocardiogram (ECG) determined LVH (P=0.04), as well as retinal changes (P=0.02). The risk of having LVH or retinal vascular changes increases significantly with each s.d. decrease in creatinine clearance, regardless of traditional cardiovascular risk factors. Moreover, patients with ECG-determined LVH and retinal changes showed lower creatinine clearance as compared to those with lesser degrees of target organ involvement (P<0.01). In conclusion, a mild reduction in creatinine clearance is associated with preclinical end-organ damage in patients with normal creatinine and primary hypertension. These data may help explain the high cardiovascular mortality observed in patients with renal dysfunction. Routine evaluation of creatinine clearance could be useful for identifying patients at higher cardiovascular risk.