ABSENCE OF AN ASSOCIATION BETWEEN SHORT-TERM BLOOD PRESSURE VARIABILITY AND MILD RENAL DYSFUNCTION IN ESSENTIAL HYPERTENSIVE PATIENTS.

Abstract

Introduction: Studies investigating the prognostic implications of short-term blood pressure (BP) variability (STBPV), expressed as standard deviation (SD) and assessed by noninvasive 24-h ambulatory BP monitoring (ABPM), yielded conflicting results. In last years further indices of STBPV have been proposed. Among these, the 24-h BP average real variability (ARV) seems to be associated with an increased cardiovascular risk more closely than the SD. Little is known about the association between mild renal dysfunction (MRD) and STBPV, and particularly between 24-h BP ARV and MRD. Aim: To analyse, in a group of essential hypertensives, the relationships between MRD and STBPV, expressed as SD of day and night-time BP and as 24-h BP ARV and between these latter, 24-h albumin excretion rate (AER) and estimated glomerular filtration rate (eGFR). Methods: We enrolled 178 untreated essential hypertensives, with and eGFR > 60 ml/min/1.73 m2. All the patients underwent 24-h ABPM. BP readings were performed automatically at 15 min intervals during the day and at 20 min intervals during night-time resting. Moreover, 24-h AER was determined and eGFR calculated using the CKDEPI equation. Subjects belonging to the I and II stages of the KDIGO classification of chronic kidney diseases (CKD) were considered as having MRD. Results: No significant difference was found between subjects with MRD (n = 43) and those without it, regarding all the indices of STBPV examined, except for SD of daytime diastolic BP that was higher (p 0.02) in patients with MRD. However, this difference lost statistical significance after adjustment for age, average daytime diastolic BP, waist circumference and triglycerides. Among the STBPV indices studied, only SD of daytime systolic BP showed a weak (p = 0.03) inverse correlation with eGFR, that disappeared after adjustment for age, gender and average systolic daytime BP in multiple regression analysis. Both 24-h systolic and diastolic ARV did not show significant correlations neither with 24-h AER nor with eGFR. Conclusions: Our results seem to suggest that in essential hypertensive patients, STBPV, even when expressed by 24-h ARV, does not influence early renal abnormalities.