blood pressure goal in kidney dz

there seems to be several recent recommendations suggesting higher BP goals than JNC7.  the american diabetes assn set the new goal at 140/80, given the results of the ACCORD trial. the european society of cardiology came out with guidelines which i sent out before (see htn guidelines european soc htn 2013 in dropbox, or doi:10.1093/eurheartj/eht151 ), which in brief set their goals as:

    --systolic bp < 140 in patients with low-to-mod cardiovasc risk and those with diabetes (best data) as well as those with hx stroke/TIA, coronary art dz, diabetic or nondiabetic chronic kidney dz, without differentiating the presence of proteinuria (less good data) 

    --in elderly <80yo with SBP >160, decrease SBP to 140-150 range

    --in fit elderly <80, SBP <140 should be considered (though i would add to check orthostatics in elderly esp with the lower goal, as well as checking symptoms). in fragile elderly, individualize goal

    --in elderly >80yo and SBP>160, goal of 140-150 range

    --DBP <90 in all, <85 in diabetics but 80-85 is safe

the quality of date for these recommendations is quite variable, as they note.

specifically for kidney disease,  KDIGO (kidney disease-- improving global outcomes) came out with guidelines in 2012 suggesting goal of 140/90 in patients without proteinuria and 130/80 if either micro or macroalbumenuria present. in this light, there was a recent retrospective analysis in the annals looking at massive VA database of patients with chronic kidney dz and all-cause mortality, stratified by achieved systolic and diastolic blood pressures (see bp goal kidney dz annals 2013 in dropbox, or Ann Intern Med. 2013;159(4):233-242. doi:10.7326/0003-4819-159-4-201308200-00004).  650K almost all men stratified into 96 different blood pressure groupings (from <80/40 to >210/110) in 10mmHg increments.  they used eGFR calculations using the Chronic Kidney Disease Epidemiology Collaboration equation. findings:

    --average age 73.8, 2.7% female, mean BMI 29

    --pretty sick population with 43% having CAD, 43% diabetes,15% cerebrovasc dz, 15% CHF and mean eGFR 50.  62% CKD stage 3A (eGFR 45-59) or 3B (30-45). not much albumenuria, with microalb/creat ratio median of 40.

    --mean baseline SBP 135 and DBP 72 (though not explicitly stated, this is pretty undoubtedly the mean baseline on lots of meds)

    --240K deaths recorded

    --the best mortality outcomes were with syst bp 140-160 and diast bp 80-90. no diff in group with proteinuria (though not much proteinuria overall) - see graph in article

    --"U"-shaped curve, with mortality pretty similar if DBP 60 or 100. SBP 120 or 180.

    --so, their conclusion: optimal bp in the 130-159/70-89 range. and "it may not be advantageous to achieve ideal SBP at the expense of lower-than-ideal DBP in adults with CKD"

impressive with huge numbers of people and lots of deaths, so able to stratify by many blood pressure groupings. but:

    --this is observational retrospective study, without even clean information on blood pressures prior to being put on meds

    --eGFR is not so accurate, esp in older group

    --the issue of diastolic hypotension is pretty murky. the higher mortality in those with lower DBP may well represent the group of patients with isolated systolic hypertension initially with a wide pulse pressure (several studies show that pts with high pulse pressures have much higher mortality, presumably related to the fact that they have stiff arteries from atherosclerotic dz). even the intervention studies in the elderly with isolated systolic hypertension (eg SHEP) are not so easy to interpret, since those with initially low DBP do worse in both the intervention and placebo groups!!-- is it because of the low DBP itself (reflecting more advanced atherosclerotic disease and arterial stiffness) or because of lowering the DBP too much (and decreasing coronary blood flow in patients at high risk of CAD). given these concerns, the SHEP trial concluded that there may be increased mortality with DBP<60 (but as noted, this is true in the untreated group as well). in fact, the achieved bp in SHEP was 143/68, with significant decrease in stroke and close to significant decrease in cardiovasc dz.  other studies suggest increased risk of stroke if DBP<65. my caveat here is that most patients with isolated systolic blood pressure put on antihypertensives have much more significant lowering of their systolic than diastolic pressures (and the goal of the hypertension in elderly of achieving SBP in the 140-150 range is usually attained without lowering DBP too much). the decrease in clinical events by lowering the systolic blood pressure at least to the 140-150 range is consistent throughout the studies, but we should make sure that we treat the individual patient (watching for signs of decreased coronary perfusion, decreased mental functioning, orthostatic hypotension, etc) and use that as the ultimate guide. there are no data that i know of for treating patients with baseline high systolic pressures and very low diastolics, such as 180/55, though i would do so cautiously. (if any of you know of studies, please let me know and i will send it around).

so, this study is interesting and seemed to get a lot of play, but really does not add that much insight.  i am mostly mentioning it to bring up the complicated issue above.