BP tight control increases life expectancy

A secondary analysis of the SPRINT trial found that those randomized to more intensive blood pressure control were projected to live an additional 6 months to 3 years (see htn SPRINT bp inc longevity jamacardiol2020 in dropbox, or doi:10.1001/jamacardio.2019.6192)

Details:
-- the SPRINT trial randomized 9361 adults >50years old who were at high cardiovascular risk, but did not have diabetes, to an intensive systolic blood pressure goal (<120 mmHg) vs standard (<140 mmHg)
    -- high cardiac risk was defined as at least one of: clinical or subclinical cardiovascular disease (not including stroke), CKD, 10-year estimated CAD risk of 15% or more, or age >75
-- mean age 68, 64% men, 58% non-Hispanic white participants
-- this secondary analysis projected the expected lifespan of those in the program if they had continued having the same benefit from intensive blood pressure lowering over time

Results:
-- estimated residual and event-free survivals were longer at every age in the intensive vs the standard arms
-- at age 50: estimated survival was 37.3 years with intensive treatment, 34.4 years with standard treatment, difference 2.9 years (0.9-5.0 years), p=0.008
    -- on reviewing their graphs, those with intensive blood pressure control showed benefit within 5 years, which increased over the next 35 years
-- at age 65: estimated survival was 24.5 years with intensive treatment, 23.3 years with standard, difference 1.2 years (0.1-2.1 years), p=0.03
    -- on reviewing the graphs, there was benefit after about 15 years, with increasing benefit with the next 15 years
--at age 80: estimated survival was 11.9 years with intensive treatment, 11.1 years with standard, difference 0.8 years (0.0 -1.6 years), p=0.04
    -- on reviewing their graphs, there was benefit within about 5 years, with continuing benefit over the next 7 years
-- though the absolute increase in life expectancy was less with more advanced age, the relative benefits were pretty consistent at 4-9%

Commentary:
--as compared to other trials of different achieved blood pressure goals, the SPRINT trial of 9361 patients achieved the largest blood pressure differential between the groups, with achieved differences of 121.4/68.7 mmHg in the intensive group vs 136.2/76.3 mmHg in the standard group; this difference was associated with a 25% decrease in cardiovascular events as well as a 27% decrease in all-cause mortality (see http://gmodestmedblogs.blogspot.com/2015/11/tighter-blood-pressure-control-sprint.html )
     -- SPRINT was terminated early because of evident benefit, after median follow-up of 3.3 years (it was supposed to be a six-year trial)
     -- during the 1^st 4 years, there was a prolonged lifespan in the intensive group of 13 additional days.

-- An evaluation of 2636 people in the elderly subgroup (>75yo) of the SPRINT trial, who achieved a blood pressure of 123.4/62.0 mmHg vs 134.8/67.2 mmHg, found a 34% reduction in cardiovascular events and a 33% reduction in all-cause mortality: see http://gmodestmedblogs.blogspot.com/2016/05/SPRINT-trial-elderly-subgroup-study-of.html

-- study limitations:
    -- as mentioned above, there were basic limitations to the SPRINT trial and its generalizability (see the referenced blogs above), especially since diabetics were excluded, a pretty substantial portion of hypertensive patients >50yo
    -- also the SPRINT study had a rather eclectic way of measuring blood pressure, as noted in http://gmodestmedblogs.blogspot.com/2017/02/blood-pressure-guidelines-for-older.html : the staff person would tell a patient that they needed to rest for 5 minutes before taking the blood pressure, would leave the room completely, would return but not speak a word with the patient and immediately take the blood pressure. Argument has been raised in the literature that the blood pressure measured in randomized controlled trials is typically 5 to 10 mmHg lower than the clinic-based blood pressure (i.e. a randomized trial with an achieved systolic blood pressure of 123, as above, may be equivalent to a clinic-based blood pressure of 130 or so)
    -- another evident limitation is that this was mathematical modeling, extending a short study’s conclusions over decades. These authors did use their current methodology in the SOLVD study of enalapril in patients with left ventricular dysfunction: they found high concordance between the data from this 3.5 year study as projected for a 12-year survival time, and the actual 12-year survival time
    -- and, of course, the modeling does assume that patients continue taking their medications consistently over the long-term, maintain the achieved blood pressure differential (at least to the extent that that happened in the original trial). And this achieved blood pressure continued to provide equivalent decreases in cardiovascular events and all-cause mortality linearly over many years, despite aging/changes in metabolism, accretion of comorbidities (including diabetes, which was not included in SPRINT), other meds being added/drug interactions, etc

So, to me this study was reassuring, especially their finding that survival was increased in the high intensity group at all ages. I have been concerned, as noted in several prior blogs, that such a low BP goal in elderly patients might be less well-tolerated, including exacerbating cognitive impairment, given that there is likely increased risk of more advanced cerebral atherosclerotic disease and pressure drop off post-stenosis.
     -- In fact there was one trial which suggest this might happen, though this trial was of patients >65yo with baseline cognitive impairment , see http://gmodestmedblogs.blogspot.com/2015/04/too-low-blood-pressure-and-cognitive.html. And the results of the above SPRINT trial may not apply to this group.
-- and, my experience in treating elderly to a lower blood pressure goal has anecdotally been quite positive (and, I do have many elderly patients with heart failure who tolerate very well quite low blood pressures on their many meds that also decrease their blood pressure to quite a low level....)

geoff​

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