Relative Absolute Risk

Gday!  This post is inspired by a few things:

A. Dr Andre Bonney (@keeweedoc) who tweeted earlier this week – 

B. This article that came out in the Lancet August 16th 2014 on Blood pressure-lowering treatment based on cardiovascular risk: a meta-analysis of individual patient data

The bottom line is:

“Lowering blood pressure provides similar relative protection at all levels of baseline cardiovascular risk, but progressively greater absolute risk reductions as baseline risk increases. These results support the use of predicted baseline cardiovascular disease risk equations to inform blood pressure-lowering treatment decisions.”

C.  A few discussions I have had with the male members of my family (I have 2 brothers, 3 sisters and 2 parents!) about the advice / prescriptions that they had received when undergoing cardiovascular preventative screening by their local GPs.  For the record – none have had any previous cardiovascular disease / events.

So let me introduce the 3 “cases” for this weeks discussion about risk.  For reference I have included a copy of the Australian Heart Foundation’s 

Use this to work out a basic risk of 5-year major cardiovascular event.  aust-cardiovascular-risk-charts .

“The Old Boy” – 73 yo retired farmer / amateur share-trader.  He has let himself go a bit – now 105kg, and has been shown to be “borderline T2DM” with a penchant for jam & cream on his scones!  He is a non-smoker, has a pretty healthy total: HDL cholesterol ratio of 6 and a BP of 145/90.

“Tootie” is now 45 years old and is a smoker.  He has been screened and has a cholesterol ratio of 5.5.  He doesn’t have diabetes  but his BP is a bit high for a ‘young’ active guy at 145/90.

“Trick” – he was unfortunately given this moniker after suffering with enuresis to a late age. “Trickle” being shortened to “Trick” later in his teens.  Like any good nickname in Australia – hard to shake if off!  Trick is only 30, he is fit, active and slim.  Non-smoker, no diabetes.  But he does eat a lot of junk – crazy amounts of bachelor food!  His cholesterol is high – with a TC:HDL ratio of 7.5.  His BP was also a bit up at 145/90.

So – there you go – 3 blokes with a set of traditional CV risk factors plotted out.  All of the same genetic stock basically.

Imagine that you are their GP.  Have a read through the Lancet paper above.

Now answer me these questions.

(Q1)  For each family member – would you commence an antihypertensive medication for primary prevention (assume no renal disease/albuminuria )?

(Q2)  For each family member what would you target as a single “intervention” to try and achieve in order to reduce each fellows’ absolute risk.

(Q3) Assuming no signs of malignant hypertension or end-organ dysfunction – at what blood pressure would you treat purely to reduce the BP – rather than aiming to reduce the longer term CV disease risk?  Name a number X/Y?


Food for thought.  Looking forward to hearing your thoughts.

From my favourite comic: XKCD – risk is always conditional! 


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