High-normal blood pressure and impaired renal function. A prospective study in a population-based cohort.

Aim. The association between high-normal blood pressure and the impairment of renal function is highly controversial. We analysed the contribution of high-normal blood pressure on incident impaired renal function. Methods. The study was performed in a population-based cohort of 1307 subjects free of diabetes, cardiovascular and renal disease at baseline, who attended both at baseline and after 6-year follow-up a metabolic screening. The outcome was incident impaired renal function, defined as a glomerular filtration rate <60 mL/min/1.73 m2. Results. Incidence of impaired renal function was 2.5%, 4.5%, 8.7% and 10.8% in optimal, normal, high-normal blood pressure and hypertension, respectively. Adjusted relative odds ratio (OR) of impaired renal function were modelled using logistic regression analyses including multiple confounders. The adjusted OR were 1.6 (95% CI 0.5-5.0) for normal blood pressure, 3.4 (1.2-10.3) for high-normal blood pressure and 3.7 (1.3-10.7) for hypertension. Results were similar after excluding overweight or obese patients. Conclusion. High-normal blood pressure is an independent predictor of impaired renal function. Trials are warranted to test if therapeutic intervention on blood pressure is justified also in subjects with high-normal blood pressure to preserve renal function.