Advertisement
Canadian Journal of Cardiology

Down the Rabbit Hole: Hypertension Guidelines, Goals and Gulfs Across the 49th Parallel

  • Ross D. Feldman
    Correspondence
    Corresponding author: Dr Ross D. Feldman, IH Asper Institute- CR1056, St Boniface Hospital, 369 Tache Ave, Winnipeg, Manitoba 2RH 2A6, Canada. Tel.: +1-204-235-3324; fax: +1-204-233-8783.
    Affiliations
    Cardiac Sciences Program, IH Asper Institute, St Boniface Hospital and the University of Manitoba, Winnipeg, Manitoba, Canada
    Search for articles by this author
      Alice: Would you tell me, please, which way I ought to go from here?The Cheshire Cat: That depends a good deal on where you want to get to.Alice: I don’t much care where.The Cheshire Cat: Then it doesn’t much matter which way you go.Alice: …So long as I get somewhere.The Cheshire Cat: Oh, you’re sure to do that, if only you walk long enough.Lewis CarrollAlice in Wonderland
      Back in the day, guidelines processes were mainly viewed as a “gentleman’s sport.” They were mostly carried out by academics in ivory towers and although they occasionally led to hurt feelings, had little lasting effects—either good or bad. Producing the guidelines was usually viewed as the “end game” and, absent extensive implementation programs and media plans, they rarely generated much attention. Especially in hypertension, and certainly in Canada; that has changed over the past 20 years. This was largely because of the institution of the Canadian Hypertension Education Program annual updates (now the Hypertension Canada guidelines) and increasingly robust dissemination, implementation, and media outreach programs. This guidelines program has been viewed as at least 1 factor contributing to Canada’s “best in class” hypertension control rates.
      One of the guiding principles of the Canadian hypertension guidelines process has been to engender as little change as possible from year to year—or at least only gradual change, that was driven primarily by compelling clinical trials evidence, rather than by expert opinion. Mediating guidelines changes by evolution, not revolution, sought to minimize confusion and resistance by end users and hence to facilitate uptake and application to practice. This go-slow approach was sharply accelerated after the publication of the landmark SPRINT, Systolic Blood Pressure Intervention Trial (SPRINT) trial results,
      • Group S.R.
      • Wright Jr., J.T.
      • Williamson J.D.
      • et al.
      A randomized trial of intensive versus standard blood-pressure control.
      and their incorporation into the 2016 Hypertension Canada guidelines.
      • Leung A.A.
      • Nerenberg K.
      • Daskalopoulou S.S.
      • et al.
      Hypertension Canada’s 2016 Canadian Hypertension Education Program guidelines for blood pressure measurement, diagnosis, assessment of risk, prevention, and treatment of hypertension.
      The SPRINT-driven shift in blood pressure (BP) targets that occurred could only be viewed as unprecedented—at least by Canadian standards. Overnight, BP targets for those at highest risk decreased by at least 20 mm Hg (including those with a Framingham Risk Score [FRS]) of > 15%) and in those older than the age of 75 years by 30 mm Hg systolic, to the SPRINT goal of 120 mm Hg. In that context, the report by Leung and colleagues,
      • Leung A.A.
      • Chang H.-J.
      • McAlister F.A.
      • et al.
      Applicability of the Systolic Blood Pressure Intervention Trial (SPRINT) to the Canadian population.
      which tabulates the effect of the SPRINT-driven shift in BP targets on those with hypertension, is especially timely and important. The authors point out that as applied in the United States, implementation of the “SPRINT” thresholds and targets would prevent 100,000 deaths annually. However, this would be at a cost, including more than 34,000 episodes of syncope and more than 88,000 occurrences of acute kidney injury. Using the rule of one-tenth for translating US estimates to Canada this still would represent substantial life-saving—but with a significant cost, of which we and our patients need to be mindful when deciding together to aim for the SPRINT target of 120 mm Hg.
      Notably, the evolutionary approach of the Canadian guidelines process and its effective implementation program with subsequent fairly uniform acceptance by end users has been in sharp contradistinction to the more revolutionary American Joint National Committee (JNC) process. Over the past 30 years US hypertension guidelines agencies often came out with recommendations supporting dramatic swings regarding BP targets and preferred therapies. These guidelines have typically been linked with only very limited implementation plans and subsequently (and predictably) with limited evidence of effectiveness in uptake to practice. Further, the effect of the JNC hypertension guidelines processes (and now its successor the American Heart Association [AHA]/American College of Cardiology [ACC] process) have been hampered by the often concurrent publication of competing guidelines with very different management recommendations—most recently the American College of Physicians (ACP)/American Academy of Family Physicians (AAFP) hypertension guidelines for adults older than 60 years of age.
      • Qaseem A.
      • Wilt T.J.
      • Rich R.
      • et al.
      Pharmacologic treatment of hypertension in adults aged 60 years or older to higher versus lower blood pressure targets: a clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians.
      Primarily in response to SPRINT, the 2017 AHA/ACC guidelines

      Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines [e-pub ahead of print]. Hypertension https://doi.org/10.1161/HYP.0000000000000066, accessed April 2, 2018.

      recommend a systolic BP threshold and target of 130 mm Hg for their high-risk patients including those 75 years of age or more and with an atherosclerotic cardiovascular disease (ASCVD) risk score of > 10%. Further, the AHA/ACC guidelines recommend a diagnosis of hypertension for all patients with BP > 130/80 mm Hg. In contrast, the 2017 ACP/AAFP guidelines maintain more traditional cutoffs for prehypertension, level 1, and level 2 hypertension. Additionally, the ACP/AAFP guidelines espouse an even higher systolic BP target of 140 mm Hg for their high-risk patients older than 60 years of age (and 150 mm Hg for everyone else), effectively ignoring any of the learnings from SPRINT. This plethora of competing US guidelines with dramatically differing recommendations led one well-known US hypertension expert (Frans Messerli) to comment that “most physicians know that guidelines are more for lawyers than for doctors” (https://www.medscape.com/viewarticle/875830#vp_3, Medscape February 8, 2017).
      Consideration of the differences between the AHA/ACC and Hypertension Canada guidelines (or between competing US guidelines) might be instructive in appreciating the differences between US vs Canadian processes. From my perspective, US hypertension guidelines have always been more expert-based and less evidence-bound than Canadian guidelines. This difference in the philosophy in crafting guidelines on either side of the 49th parallel might well underlie the differences in targets between the AHA/ACC guidelines and Hypertension Canada guidelines, and might underlie the discrepancies in targets between competing US guidelines processes (Table 1). Whereas the Hypertension Canada targets were SPRINT-based, the AHA/ACC targets can only be viewed as SPRINT-inspired. The AHA/ACC guidelines advocate for a target BP that was not tested in SPRINT (130 mm Hg not 120 mm Hg) and uses a risk cutoff that is lower than recommended in SPRINT (10% vs 15%) and with a risk calculator that overestimates risk to an even greater extent than the FRS. Notably in this range the ASCVD score has been shown to overestimate risk by 186% and 71% in men and women, respectively.
      • DeFilippis A.P.
      • Young R.
      • Carrubba C.J.
      • et al.
      An analysis of calibration and discrimination among multiple cardiovascular risk scores in a modern multiethnic cohort.
      Further, the AHA/ACC BP target is not on the basis of automatic office BP measurements— the primary means of BP monitoring used in SPRINT.
      Table 1Comparison of guidelines recommendations for management of high-risk patients with hypertension
      GuidelineHypertension CanadaACC/AHAACP/AAFP
      BP target for high-risk patients (SBP), mm Hg120130140
      Recommended BP monitorAutomated office blood pressure devicesNot specifiedNot specified
      10-Year CV risk, % for definition of “high risk”15%10%Not specified
      Recommended CV risk estimatorFramingham Risk ScoreACC/AHA pooled risk equations estimator (ASCVD)Not applicable
      AAFP, American Academy of Family Physicians; ACC, American College of Cardiology; ACP, American College of Physicians; AHA, American Heart Association; ASCVD, atherosclerotic cardiovascular disease; BP, blood pressure; CV, cardiovascular; SBP, systolic BP.
      Set against this morass of management guidelines for hypertension in the United States is the interesting analysis by Goupil and colleagues, reported in this issue of the Canadian Journal of Cardiology.
      • Goupil R.
      • Lamarre-Cliché M.
      • Vallée M.
      The 2017 American College of Cardiology/American Heart Association vs Hypertension Canada high blood pressure guidelines and potential implications.
      In it, they compare the effect of applying the AHA/ACP guidelines vs Hypertension Canada’s in terms of the numbers of Canadians: (1) diagnosed with hypertension; (2) treated for hypertension; or (3) having a different BP target. The answers are quantitatively interesting, respectively: (1) 8.7% more; (2) 3.4% more; and (3) 17.2% more. However, qualitatively these findings are absolutely predictable. As noted previously, the higher numbers labelled as hypertensive and targeted for treatment follows from the AHA/ACC guidelines which advocates a much lower threshold for the diagnosis for hypertension, and uses a lower risk threshold for which to apply the high-risk label (ie, 10% according to the ASCVD risk score), albeit while espousing a higher target BP for high-risk patients (130 mm Hg).
      What can we learn from these important reports in aggregate? First, that regardless the guidelines we use, in the post-SPRINT era there are more patients than ever who can expect clear benefit from applying lower targets for their BP control—but at the cost of increased risk of adverse effects. This underscores the reminders that undertaking these more aggressive goals should be on the basis of frank discussions with patients outlining benefits as well as risks, and that management should be on the basis of automatic office BP readings, which in this lower range, might well correspond with higher ambulatory BP readings.
      • Rinfret F.
      • Cloutier L.
      • Wistaff R.
      • et al.
      Comparison of different automated office blood pressure measurement devices: evidence of nonequivalence and clinical implications.
      • Godwin M.
      Measuring blood pressure and diagnosing hypertension in the physicians office in the age of automated devices: time for guidelines to reflect reality.
      • Rinfret F.
      • Cloutier L.
      • L’Archevêque H.
      • et al.
      The gap between manual and automated office blood pressure measurements results at a hypertension clinic.
      • Jegatheswaran J.
      • Ruzicka M.
      • Hiremath S.
      • Edwards C.
      Are automated blood pressure monitors comparable to ambulatory blood pressure monitors? A systematic review and meta-analysis.
      These studies also remind us that on a public health basis, getting the guidelines right does matter. For every adjustment in BP targets, there are benefits and there are costs—for patients as well as in our publicly-funded health care system, for all Canadians.
      However, perhaps most importantly, we should be reminded of something that neither report talks about: that it is better to have even suboptimal guidelines that are followed than it is to have “perfectly” crafted and up-to-date guidelines that are ignored. To illustrate this, I often relate the chronicle of the Intermountain Health Care System ventilator guidelines for patients with acute respiratory distress syndrome (ARDS).
      • Leonhardt D.
      Making health care better.
      These were instituted in the 1990s in an effort to increase ARDS survival rates in their intensive care units. These guidelines were instituted as “default” orders that were implemented in the absence of any customized orders from the intensive care unit physicians. When those guidelines were reviewed months after implementation, it was concluded that if not “wrong” they were at least “deeply flawed.” Notwithstanding over this period their ARDS survival rates had increased to 4 times the national average. Punchline: even mediocre guidelines are better than no guidelines. Thus, beyond considering the effect of application of either updated Canadian guidelines or the AHA/ACC guidelines or even the ACP/AAFP guidelines, we should remember that we are way past the glory days of the past millennium when guidelines development was a gentleman’s sport. Guidelines today, for hypertension or for any other disease, should be judged more for how effectively they are applied and less for how effectively they are crafted. Notwithstanding, in my admittedly biased view, in both respects Canada still owns the podium.

      Disclosures

      R.D.F. has served as President of the Canadian Hypertension Society, as Chair of the Steering Committee of the Canadian Hypertension Education Program, and as President of Hypertension Canada. He has been involved in the development, dissemination, and implementation of Canadian hypertension guidelines since 1991.

      References

        • Group S.R.
        • Wright Jr., J.T.
        • Williamson J.D.
        • et al.
        A randomized trial of intensive versus standard blood-pressure control.
        N Engl J Med. 2015; 373: 2103-2116
        • Leung A.A.
        • Nerenberg K.
        • Daskalopoulou S.S.
        • et al.
        Hypertension Canada’s 2016 Canadian Hypertension Education Program guidelines for blood pressure measurement, diagnosis, assessment of risk, prevention, and treatment of hypertension.
        Can J Cardiol. 2016; 32: 569-588
        • Leung A.A.
        • Chang H.-J.
        • McAlister F.A.
        • et al.
        Applicability of the Systolic Blood Pressure Intervention Trial (SPRINT) to the Canadian population.
        Can J Cardiol. 2018; 34: 670-675
        • Qaseem A.
        • Wilt T.J.
        • Rich R.
        • et al.
        Pharmacologic treatment of hypertension in adults aged 60 years or older to higher versus lower blood pressure targets: a clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians.
        Ann Intern Med. 2017; 166: 430-437
      1. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines [e-pub ahead of print]. Hypertension https://doi.org/10.1161/HYP.0000000000000066, accessed April 2, 2018.

        • DeFilippis A.P.
        • Young R.
        • Carrubba C.J.
        • et al.
        An analysis of calibration and discrimination among multiple cardiovascular risk scores in a modern multiethnic cohort.
        Ann Intern Med. 2015; 162: 266-275
        • Goupil R.
        • Lamarre-Cliché M.
        • Vallée M.
        The 2017 American College of Cardiology/American Heart Association vs Hypertension Canada high blood pressure guidelines and potential implications.
        Can J Cardiol. 2018; 34: 665-669
        • Rinfret F.
        • Cloutier L.
        • Wistaff R.
        • et al.
        Comparison of different automated office blood pressure measurement devices: evidence of nonequivalence and clinical implications.
        Can J Cardiol. 2017; 33: 1639-1644
        • Godwin M.
        Measuring blood pressure and diagnosing hypertension in the physicians office in the age of automated devices: time for guidelines to reflect reality.
        Can J Cardiol. 2017; 33: 963-964
        • Rinfret F.
        • Cloutier L.
        • L’Archevêque H.
        • et al.
        The gap between manual and automated office blood pressure measurements results at a hypertension clinic.
        Can J Cardiol. 2017; 33: 653-657
        • Jegatheswaran J.
        • Ruzicka M.
        • Hiremath S.
        • Edwards C.
        Are automated blood pressure monitors comparable to ambulatory blood pressure monitors? A systematic review and meta-analysis.
        Can J Cardiol. 2017; 33: 644-652
        • Leonhardt D.
        Making health care better.
        The New York Times Magazine. November 3, 2009; (Available at: http://www.nytimes.com/2009/11/08/magazine/08Healthcare-t.html. Accessed April 2, 2018)