13. mean arterial BP (taken to be 1/3 of the difference in mm Hg between diastolic BP and systolic BP, added to the diastolic BP) of 130 mm Hg or greater; (if the mean arterial BP is 130 mm Hg or greater but can be reduced by treatment to < 130 mm Hg, with systolic BP in the 150 169 mm Hg range, the patient may be entered).