In patients aged 70 to 80 years, risk increased once systolic BP was less than 135 mm Hg or diastolic BP o75 mm Hg, while the risk increasing when systolic BP was o140 mm Hg or diastolic BP These relationships may be due to confounding and should not be used to set BP targets in this population. In preparing the evidence review for this guideline, the ERT found four studies involving elderly patients in which treating to differing targets for BP was part of the study design (Supplementary Table 67 online).149,389,391 393 The Shanghai Trial of Nifedipine in the Elderly (STONE) involved 1632 patients aged 60 79 years with a systolic BP Z160 mm Hg, or a diastolic BP Z96 mm Hg, who were randomized to nifedipine or placebo.392 The mean achieved BP was 147/85 mm Hg in the nifedipine group and 156/ 92 mm Hg in the placebo group and although there was no significant difference in all-cause mortality, there were reductions in the rates of stroke and severe arrythmia in the lower-BP nifedipine treated group. Exclusion criteria included secondary hypertension and a blood urea nitrogen level Z40 mg/dl (14.3 mmol/l). The Hypertension in the Very Elderly Trial (HYVET), involving patients 80 years of age or older, provided further assurance that BP lowering treatment of very elderly patients with a sustained BP of Z160 mm Hg is beneficial.149,391 Aiming to treat to a target BP of systolic o150 mm Hg and diastolic o80 mm Hg in the active-treatment group, the investigators achieved a BP of 145/79 mm Hg with indapa- mide plus perindopril (if needed), compared to 159/ 83 mm Hg with placebo. They demonstrated a reduction in the rates of all-cause mortality and stroke in the low-BP active-treatment group over a median 1.8 years of follow-up. 