When this trial was being designed, there was accumulating evidence that treatment of blood pressure across a broad range of patients was beneficial for reducing cardiovascular events. it was not known however, if the same treatment benefits apply to those over 80 years old. Most HTN trials by this time had excluded patients over 80 years old and a noted inverse correlation of blood pressure and risk of death among elderly was known at the time. Although this inverse correlation may have been due to confounders associated with low BP (i.e. cancer, dementia, MI, heart failure), there were real concerns about treating patients with hypertension in this age range. A retrospective cohort analysis was mentioned in the introduction of the HYVET Trial (Oates 2007) which showed shorter survival for >80 year old patients who were treated with antihypertensive medications and had a SBP <140mmHg. Overall, it was suspected that there was benefit to treating hypertension in these patients, but the benefits were unknown and a fear of increased harm was very present.
This trial enrolled 4,761 very elderly individuals (at least 80 years old) he had persistent HTN (defined as SBP 160-199). after a two-month run in Phase, 3845 patients were randomized to active treatment with blood pressure medications or a placebo. patients in the act of treatment arm utilizing a thiazide diuretic (indapamide) and possibly an ACE (perindopril) and other antihypertensive medications, if needed, to target a goal BP of <150/80mmHg. The primary end point was the rate of fatal or nonfatal stroke (excluding TIA). Secondary end points included death from any cause, death from cardiovascular causes, death from cardiac causes, and death from stroke. The median follow-up was 2 years. Although there was no statistically-significant difference in the primary end point between the two groups (P=0.06), there was a 21% reduction in the rate of death from any cause (P=0.02). There was also a 64% reduction in the rate of heart failure (P=<0.001). The trial results did note the non-significant outcomes of a 30% reduction in the rate of fatal or non-fatal stroke, a 39% reduction in the rate of death from any stroke, a 23% reduction in the rate of death from CV causes. You may be wondering what the blood pressure reduction in the control group was, being that they used a placebo. In the placebo group, the BP was reduced by about 15/7mmHg. As expected, the active treatment group BP was reduced more — by about 30/13mmHg. Overall, the trial did show that there was benefit to treatment of HTN in patients 80 years old or older in regards to death from any cause with trends toward a reduction in stroke.
The HYVET Trial: Beckett, N. S., Peters, R., Fletcher, A. E., Staessen, J. A., Liu, L., Dumitrascu, D., ... & Belhani, A. (2008). Treatment of hypertension in patients 80 years of age or older. New England Journal of Medicine, 358(18), 1887-1898.
HYVET Trial PMID: 18378519
Useful Summaries of the HYVET Trial: Wiki Journal Club
Other Useful References:
Oates, D. J., Berlowitz, D. R., Glickman, M. E., Silliman, R. A., & Borzecki, A. M. (2007). Blood pressure and survival in the oldest old. Journal of the American Geriatrics Society, 55(3), 383-388.