dr. saver: the incidence of stroke approximately doubles for every decade over the age of 45. two-thirds of all strokes occur over the age of 65. but stroke is also not uncommon in mid-adult life, or even in childhood. and there are more strokes in patients under the age of 45 than there are cases of multiple sclerosis. the risk factors for stroke, in certain respects, resemble the risk factors for other cardiovascular diseases. dr. saver: high blood pressure, hypertension, is the number one modifiable risk factor for stroke. high blood pressure increases the risk of stroke fivefold compared to people who don't have high blood pressure. the conventional definition for high blood pressure is having a systolic blood pressure-- the upper number-- that's 160 or higher, and the diastolic blood pressure, or lower number, that's 85 or 90 or higher. if you have blood pressure in that range, then to work with your physician in lowering the blood pressure. usually the first steps are lifestyle changes: d

reporter: which brings us to the main cost-saver, reducing the priciest part of health care: hospital stays, especially for the sickest among us, who, says drm ferris of partners, account for the biggest portion of all costs. >> about 50% of the total is accounted for by 5% of the patients. they're so complicated that, left to their own devices, they will bounce between providers, and that movement between providers, uncoordinated, leads to waste in the system. >> reporter: so, partners assigns care managers to coordinate the treatment of high-risk cases. the elderly, for example, fall so frequently that, in 2010, over two million were treated in the e.r. >> and emergency room doctors really don't have a lot of choices; they're going to admit that patient. but when someone who knows the patient shows up in the emergency room and says, "actually, i know this person; it's okay; she'll be safe going home; i'm going to follow up closely with her," that changes the equation. >> reporter: in a 2006 trial run, partners care managers reduced high-risk patient hospitalizations by 20%... ( ambulance siren ) ...keeping patients out of the hospital. th