Role of natriuresis and frailty in blood pressure regulation in elderly people

Objective: The objective of the study is to investigate, in elderly people, the relationship between natriuresis, frailty and blood pressure (BP). Design and method: The FRASNET geriatric population (1204 subjects) is an Italian observational cohort that includes frail (35%), pre-frail (37.3%) and robust (27.7%) subjects. They have been characterised for BP, renal function, sodium intake (by Kawasaki formula), anthropometric data, cognitive status, quality of life, comorbidities, and chronic therapies. ANOVA and conditional inference tree analyses have been carried out. Results: 745 participants out of 1203 (60%) were under anti-hypertensive treatment. Increased visceral fat, male sex and lower number of medications taken are risk factors for suboptimal control of BP (71.4%). An inferential analysis evidenced (Fig. 1) a first node between male and female, a second one according to age (75 y), a third with natriuresis (217 mEq/24h). Non-frail subjects presented the highest values for both systolic and diastolic BP; the frail group presents systolic BP values below the threshold of 140 mmHg. BPs are negatively correlated with frailty status (systolic p = 0.048, diastolic p <0.001, Figure 2). Conclusions: Frailty and blood pressure follow an inverse tendency: the higher the severity of the frail status, the lower the blood pressure. The relationship between BP and natriuresis is preserved only in young women whereas in very old people (>75 y) is no more present. This evidence is supported by physiological explanations and suggest to be cautious in salt reduction intake in elderly people.