Monday, November 23, 2015

Which patients should SPRINT to a systolic goal of 120?

- Jennifer Middleton, MD, MPH

Two weeks ago, I wrote about the controversy surrounding the early closure of SPRINT. That same day, the SPRINT research group published the results of their study; for SPRINT participants, a systolic blood pressure (SBP) goal of 120, compared to 140, resulted in lower risk of several cardiovascular events including mortality, but we should proceed with caution before applying these findings to our patients.

SPRINT was a randomized controlled trial that enrolled over 9000 community-dwelling participants across 102 clinical sites in the United States. Participants had to be at least 50 years old, have a SBP between 130 and 180, and had to have "an increased risk of cardiovascular events," which the research group defined as prior cardiovascular disease (CVD) excluding stroke, chronic kidney disease (CKD), a 10-year Framingham risk score of at least 15%, or age of at least 75 years. Participants were excluded if they had diabetes or a history of a stroke. The research group provided a suggested protocol for antihypertensive medications. Participants in the intensive group had a mean SBP of 121.4 mmHg, and participants in the control group had a mean SBP of 136.2 mmHg.

The researchers' primary outcome was a composite of myocardial infarction, acute coronary syndrome, stroke, heart failure, or death from CVD, and the rate of the composite outcome was lower in the intensive group (hazard ratio 0.75 [0.64-0.89]). The number needed to treat to prevent a primary outcome event was 61. The intensive treatment group also had a higher likelihood of worsening renal function, and since the study was stopped early, it's impossible to know how likely it is that those renal effects would be irreversible. Other adverse events more common in the intensive treatment group: hypotension, syncope, and electrolyte abnormalities.

The study population may not be generalizable to your practice; it's important to note that these findings should not be extrapolated to suggest that all of our adult patients should aim for SBPs below 120. Certainly, that may be a reasonable goal for patients over the age of 50 with "an increased risk of cardiovascular events," but I suspect that many of our patients over the age of fifty with hypertension (and without diabetes) do not have those risk factors. Those patients who do meet the study parameters should still engage in patient-centered decision making regarding the risks of intensive treatment.

Dr. Lin commented on other challenges of applying this study to our patients; office blood pressure measurements, for example, are rarely done with the level of precision they were measured with in SPRINT. Aggressively adjusting medication doses based on what may be inaccurate office BP readings could potentially cause patients significant harm. Most of the time, the JNC 8 guidelines are likely to be more applicable to the patients in our offices than SPRINT's narrowly defined parameters.

Has SPRINT changed how you treat hypertension?

2 comments:

  1. Inaccuracy of blood pressure measurements lacking adequate precision to allow for medication dosage adjustments is something that we can individually change as a national priority. Three bp readings done after five minutes of sitting using an accurate standardized, computerized sphygmomanometer should be something we as professionals, who see hypertensive patients as few as 4 times annually, manage with adroit. This was apparently done for this study 9000 times. If nothing else SPRINT can change how we review and insist on standardization of data collection in the management of hypertensive patients.

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