The Systolic Hypertension in the Elderly Program (SHEP) was the first clinical trial to demonstrate the efficacy of low-dose antihypertensive medication in preventing stroke in older individuals with isolated systolic hypertension (ISH). The trial was multicentered, double-blind, randomized, placebo-controlled and involved 4,736 men and women, black and white, age 60 and over with ISH. Results showed a highly significant 36% reduction in nonfatal plus fatal stroke over 5 years in the group treated with active medication (low-dose chlorthalidone was step one), compared with the placebo group. Nonfatal plus fatal coronary disease and cardiovascular disease were also significantly reduced with antihypertensive medication, by 27% and 32% respectively, and total mortality was lower by 13%.