To investigate whether there is an interaction between effect of treatment for hypertension and frailty in older adults , we calculated the frailty index ( FI ) for all available participants from the HYpertension in the Very Elderly Trial ( HYVET ) study , a double-blind , placebo-controlled study of antihypertensives in people with hypertension aged @ and over , and obtained frailty adjusted estimates of the effect of treatment with antihypertensive medication on risk of stroke , cardiovascular events , and mortality .