What are the odds that your blood pressure medication will really help you?

The answer might surprise you, not to mention a lot of people who have been labeled chronically ill.

Because that’s what it really amounts to:

Hypertension is a chronic disease, or rather a chronic condition.

When that label comes at an arbitrarily defined threshold of blood pressure then you are absolutely justified to seek an answer to this post’s title question. Particularly when economic interests are involved.

Such as the annual US$ 20 Billion market for anti-hypertensive medication.

That market virtually grew overnight when in 2017 the American College of Cardiology and the American Heart Association lowered the threshold for hypertension from 140/90 to 130/80 mmHg.

31 million Americans “became” chronically diseased “overnight”. The prevalence of hypertension among adults aged 40 and over jumped from 37% to close to 60% [1].

 Here is why I don’t agree with this threshold-fixing.

The True Risk Of Elevated Blood Pressure

Lowering elevated blood pressure, whatever “elevated” means, should reduce cardiovascular death (mortality) and disease (morbidity).

Only it doesn’t, a least not in the way it is portrayed to the public.

The gospel coming from, among others, the Framingham study tells us that there is a continuous increase of death risk as a function of blood pressure. With no detectable lower bound down to systolic pressure of 115 mmHg.

Courtesy of a study by Port et al. [2], the graph below shows how this statement is typically presented as a result of a statistical method that we call a logistic regression.

 

 

What this picture does not tell you is that the choice of statistic (logistic regression) produces a smoothed line over the raw data.

 That’s a problem when those raw data look like this:

 

 

It is easy to see that the smooth line of the first graph does not describe the reality very well.

Cardiovascular and non-cardiovascular deaths show no significant upwards trend until about 160 mmHg. From then on the risk increases exponentially.

In such a situation a splined logistic regression is the more appropriate statistic model to use. That’s the type that accounts for a segmentally different relation between death and blood pressure.

When applying the more appropriate statistic there is no more significant association between death and “hypertension” up to the age-adjusted 70th percentile of blood pressure.

You are probably less interested in the finer points of statistics, than you are interested in a tool to help you answer the question: what is that 70th percentile for my age and gender.

 Calculate Your Personal Risk

You can calculate your age-adjusted 70th percentile of systolic blood pressure using the following formula:

• For men: 120 + (2/3 x age); example for a 50-year old man: 120 +(2/3 x 50) = 153 mmHg
• For women: 114 + (5/6 x age); example for 50-year old woman: 114 +(5/6 x 50) = 156 mmHg

You can find the Port paper from the bibliography below and even download it from the journal Lancet, one of the most respected medical journals.

 I bet, when you compare your 70th percentile threshold with your actual blood pressure your worries, if you have any, may become a lot more moderate.

 OK, so much about death, but what about cardiovascular disease? You don’t want to get that either.

The answer is surprisingly similar.

The Numbers Needed to Treat and to Harm

A very recent study looked at the number needed to treat (NNT) and the number needed to harm (NNH) in the context of blood pressure medication [3].

The NNT describes how many people need to take a drug to prevent one single event (in our context: heart attack, stroke etc.) compared to not taking the drug.

The NNH tells you how many people will need to take the drug to observe one harmful event or side effect.

Ideally the NNT is as small as possible, and the NNH as large as possible.  

In our case, no benefit of taking BP lowering medication was observable (over 3.5 years of monitoring) for people with a systolic blood pressure  (SBP) <140 mmHg.

At a SBP between 140 mmHg and 159 mmHg, the NNT was 47 and the NNH was 39. That is, 47 people need to be treated to prevent 1 major adverse cardiovascular event (MACE), whereas the remaining 46 would have experienced no event, even if they didn’t take the drug.  

And for every 39 drug-treated individuals there is one harmful event or side effect.

It has always escaped me why those who should inform the lay public about the benefits and harms of what they prescribe, shy away from these very illustrative numbers.

An earlier meta-analysis of studies which investigated the outcomes in treated vs. untreated hypertension (140-160 mmHg systolic & 90-100 mmHg diastolic) concluded that there was no benefit from treatment for heart disease, stroke or total cardiovascular events.

Oh, yes, and almost 10% of treated patients discontinued treatment, because of negative side-effects.

Mind you, this meta-analysis was performed by evidence-based medicine’s non-profit white knight, the Cochrane Collaboration [4].

Hypertension: Not To Be Taken Lightly

The latest iteration of the European Society Of Hypertension (ESH) guideline for managing arterial hypertension  reflects this cumulative evidence. It sets the “red line” for drug treatment at 140/90 mmHg.

But it also makes one thing very clear:

Elevated blood pressure is a warning not to be taken lightly. For 9 out of 10 hypertensive persons, their condition is self-inflicted. Too much weight, too little exercise and a lot of other unhealthy habits are the dominant causes of hypertension.

Which also means, correcting these causes may very well drive your blood pressure down, too.

That’s why all the guidelines agree on lifestyle change as the first line of defense against the potentially debilitating consequences of long-standing hypertension.

So, if you succeed in managing your blood pressure through lifestyle adjustments, you wouldn’t need to worry about the odds of your drugs helping, or harming, you in the first place.

Hashtags

#hypertension

#hypertensionawareness

#NNT

 

References

[1]     Kaul S. Evidence for the Universal Blood Pressure Goal of <130/80 mm Hg Is Strong: Controversies in Hypertension - Con Side of the Argument. Hypertension 2020;76:1391–9. doi:10.1161/HYPERTENSIONAHA.120.14648.

[2]     Port S, Demer L, Jennrich R, Walter D, Garfinkel A. Systolic blood pressure and mortality. Lancet 2000;355:175–80. doi:10.1016/S0140-6736(99)07051-8.

[3]     Mao Y, Ge S, Qi S, Tian QB. Benefits and risks of antihypertensive medication in adults with different systolic blood pressure: A meta-analysis from the perspective of the number needed to treat. Front Cardiovasc Med 2022;9:1–12. doi:10.3389/fcvm.2022.986502.

[4]     Diao D, Wright JM, Cundiff DK, Gueyffier F. Pharmacotherapy for mild hypertension. Cochrane Database Syst Rev 2012;8:CD006742. doi:10.1002/14651858.CD006742.pub2.