Nocturnal Fall in Blood Pressure in the Elderly is Related to Presence of Hypertension and not Age

Abstract

Morfis L, Howes LG. Nocturnal fall in blood pressure in the elderly is related to presence of hypertension and nor age.Aims: To determine whether the reduced nocturnal fall in blood pressure (BP) reported in elderly hypertensives is due to ageing or to the presence of hypertension. Methods: Twenty-four hour ambulatory BP recordings of 68 normotensive elderly were compared with those of 55 elderly treated hypertensives, aged 63–88 years. Mean night-time BPs were calculated from the average of readings during sleep and mean daytime BPs from the remaining recordings. The maximum day-night BP differences were calculated. Plasma renin, aldosterone and noradrenaline were measured. Results: Normotensive subjects were aged 72.0 ± 4.7 years and treated hypertensives 73.7 ± 4.9 years (p = 0.049). Normotensives had lower systolic BP (SBP) than hypertensives (125 ± 12mmHg versus 135 t 14 mmHg, p < 0.01). The fall in SBP at night was greater in normotensives than in hypertensives (18 ± 9 versus 14 ± 9 mmHg, p < 0.02). Non-dipping occurred in 24% of all subjects, with 59% of these being hypertensives. The nocturnal fall in SBP was not related to age (β = -0.04, p < 0.62) but was inversely related to a history of hypertension (X2 = 5.82, p = 0.02). Serum noradrenaline was significantly related to nocturnal SBP fall (0 = 0.28, p = 0.01). Conclusions: Elderly normotensives have a greater decline in nocturnal SBP than treated elderly hypertensives. The failure of SBP to fall at night appears to be more a feature of hypertension than of ageing. Early morning noradrenaline estimations are higher in patients with a greater nocturnal blood pressure fall.