Prognostic Significance of Home Arterial Stiffness Index Derived From Self-Measurement of Blood Pressure: The Ohasama Study

BACKGROUND Arterial stiffness is a stroke risk factor. The home arterial stiffness index (HASI) can be calculated from self-measured blood pressure using the same formula as the calculation of ambulatory arterial stiffness index (AASI). METHODS In 2,377 inhabitants (baseline age, 35-96 years) without a history of stroke, home blood pressure was measured once every morning for 26 days (median). HASI was defined as 1 minus the regression slope of diastolic over systolic on home blood pressure in individual subjects. The standardized hazard ratio (HR) of HASI was computed for cerebral infarction, while adjusting for sex, age, body mass index, pulse pressure, mean arterial pressure, heart rate, day-by-day variability of systolic blood pressure, smoking and drinking habits, serum total cholesterol, diabetes mellitus, and antihypertensive treatment. RESULTS A total of 191(8.0%) cerebral infarctions and 75(3.2%) hemorrhagic strokes occurred over a median of 13.8 years. Mean +/- s.d. of HASI was 0.60 +/- 0.23 units. An increase in HASI of 1 s.d. was associated with an increased HR for cerebral infarction in all subjects (1.19, P = 0.034), men (1.37, P = 0.002), and normotensive subjects (1.46, P = 0.006), but not in women or hypertensive patients (P > 0.56). For hemorrhagic stroke, HASI was not prognostic. CONCLUSIONS HASI predicted cerebral infarction independent of pulse pressure and other risk factors in men and normotensive subjects. One important role of home blood pressure measurement is early recognition of onset of hypertension in normotensive subjects who are at risk of developing hypertension. HASI provides additional benefits for such subjects.