[ed. note: Michael Jorrin, who I dubbed “Doc Gumshoe” years ago, is a longtime medical writer (not a doctor) who writes for us a couple times a month about health issues and trends. He does not typically focus on specific investment opportunities, but has agreed to our trading restrictions… as with all of our authors, he chooses his own topics and his words and opinions are his alone]
In the past month or so there have been a couple of disquieting pronouncements about health matters that rattled around the media world, not quite rivaling the happenings in the political arena as a focus of speculation and concern, but which surely have captured the attention of a good many people, including perhaps some denizens of Planet Gumshoe.
Pronouncement number one was that that for anyone whose ten-year risk of sustaining a significant cardiac incident (such as a heart attack or a stroke) is 10% or higher, systolic blood pressure should be less than 130 mmHg. Virtually all the medical organizations that focus on heart health have gone along with this recommendation, which considerably tightens previous blood pressure guidelines. Limiting that recommendation to persons with a 10% ten-year risk doesn’t amount to much, since just about every human over the age of 65 is at that risk level or greater, due to age alone. Based on that recommendation, half the population of the US would be defined as having high blood pressure.
Pronouncement number two was that women using hormonal contraceptives, whether the pill or the patch, were at a higher risk of breast cancer than women who did not use hormonal contraceptives. There was no specific recommendation associated with this announcement, but it got rapidly linked with previous concerns about hormone replacement therapy, which took a colossal hit when the early results of the Women’s Health Initiative were presented to the public. I can readily predict that many, many women would immediately think about switching contraceptive methods, with what outcomes it’s impossible at this early stage to predict.
Doc Gumshoe is here to tell you to view both of those announcements with a healthy dose of skepticism.
The 2017 blood pressure guidelines
Let’s look first at the blood pressure recommendation. This came about mostly based on the results of the Systolic Blood Pressure Intervention Trial (SPRINT), which was published in the New England Journal of Medicine on 26 November 2015 and widely discussed in the medical community (N Engl J Med 2015;376:2103-2116). The one-sentence take-away was that in non-diabetic patients at high risk for cardiovascular events, treating elevated blood pressure to a target level of 120 mmHg, compared with a target level of 140 mmHg, resulted in lower rates of signal cardiac events.
The results of the SPRINT trial reverberated through the entire cardiology community, and about two years later, on 13 November 2017 the American College of Cardiology, the American Heart Association, and about eight other prestigious medical societies came out with the recommendation to treat blood pressure in patients like those in the SPRINT trial to a target blood pressure of less than 130 mmHg. The case seems to be open and shut.
So where does Doc Gumshoe get off raising any doubts about this? Before you conclude that Doc Gumshoe is nothing more than a pig-headed contrarian, let me assure you that I am by no means alone in my skepticism; numerous eminent health professionals have voiced their doubts that the results of the SPRINT trial would be replicated in the population at large. Moreover, “at large” should be in 144-point type, since the number of people who would need to be medicated according to the new guidelines is large indeed.
Here’s what the SPRINT trial did. It was conducted at 102 clinical sites in the US, including Puerto Rico. Participants had to be at least 50 years of age, have a baseline BP between 130 and 180 mmHg, and be at increased risk for cardiovascular events, which were defined as established CV disease, or chronic kidney disease, or a 10-year risk of 15% or higher based on the Framingham risk calculator, or age 75 years or higher. Patients with diabetes or who had sustained strokes were excluded.
A total of 9,361 individuals with a baseline systolic blood pressure (BP) above 130 mmHg were enrolled and assigned to two treatment cohorts. The target BP in one group was less than 120 mmHg, while in the other group it was less than 140 mmHg. At baseline, systolic BP in the two groups was identical (139.7 mmHg), while diastolic BP was two-tenths of a millimeter of mercury apart (78.2 vs. 78.0). All the subjects were taking BP medications at baseline, an average of 1.8 medications per subject in both groups.
The procedures for recording BP were painstaking in the extreme in the effort to prevent what is called “white coat” hypertension, meaning that persons having their BP measured by a health professional tend to register significantly higher readings. Blood pressure changes quickly and by quite large intervals due to many different factors, including external physical activity, internal stress, surroundings, and miscellaneous incidental events. For example, I used to have my annual physical at the office of my excellent regular physician. I would walk briskly to his office, be greeted by his nurse/office manager, who would immediately prepare me for the examination and do a BP reading. It was invariably pretty high. Once I sneezed while the cuff was on my arm, and the BP reading went through the roof. Then I would have my going over, and my physician would discuss all the results with me. And then he would do a second BP reading, at which point the systolic BP would usually be 30 or 40 points lower.
In the SPRINT trial, BP readings were recorded as an average of three readings taken while the patient was seated in a quiet room after five minutes of rest with no staff members in the room. This was meant to assure that the BP was not elevated due to external factors, but really represented the subject’s resting, stress-free BP.
This is far from the usual standard practice.
The trend favoring the more intensive treatment regimen emerged fairly early, and the trial was suspended after about 39 months, when it emerged that the rate of significant outcome events in the intensive treatment group was about 25% lower than in the standard treatment group. Those results sounded like a big deal in the cardiology community.
However, on closer examination, how big a deal is this? The real numbers – not the relative risk numbers, but the actual results – are somewhat more modest. Of the 4,678 participants in the intensive treatment group, 243 sustained a primary outcome event, while of the 4,683 in the standard treatment group, 319 sustained such an event. During the 39 months of the study, in percentage terms, 5.2% of the intensive treatment group had a significant cardiac event, compared with 6.8% of the standard treatment group. The annual incidence of primary outcome events was 1.65% in the intensive treatment group versus 2.19% in the standard treatment group. That’s about half a percentage point difference.
Of course, that half a percentage point, applied to a potential population of a hundred million or more, would make a real and important difference in the lives of many thousands of people. The question is, could the standards employed in the SPRINT trial be duplicated in general practice across the nation?