How much longer will you live if you take a statin?
About a year ago I submitted a paper to the BMJ entitled ‘Statins in secondary prevention, lives saved or lives extended.’ To be more accurate, I was the lead author of the paper. So I should say ‘we’ submitted a paper. I have to report that the paper was rejected, re-written and rejected again. In the end I couldn’t get it published.
The main aim of the paper was to point out that the most important reason why someone would take a ‘preventative medicine’ of any sort, was to increase their life expectancy. The question ‘how much longer will I live if I take this tablet for, say, five years?’ Seems a reasonable question to ask and, in turn, have answered. Interestingly no patient has ever asked me this question, so I have never had to answer it.
What we have instead is the repeated use of relative risk. Which is often framed in the following type of way: ‘Atorvastatin/Lipitor will reduce the risk of dying of a heart attack by 36%’… and suchlike. Whilst that figure is true, or at least it was true in one study funded and run by Pfizer… who sell atorvastatin, I knew that a figure like that was horribly misleading. It gave the impression of a gigantic reduction in risk. ‘Your risk of dying of heart disease will be reduced by more than a third!’ Surely you would be mad not to take it, wouldn’t you?
However, how does a figure like that pan out in the most important outcome of all. Namely, increase in life expectancy? I had done a few ‘back of a cigarette packet calculations’ on this, and I was getting some pretty unimpressive figures. But to get it absolutely right I contacted a professor of statistics at the Medical Research Council and asked him if he could work out an exact figure, using real mathematics.
We chose the two most positive studies on statins ever done. The Scandinavian Simvastatin Survival Study (4S) and the Heart Protection Study (HPS). These were secondary prevention studies. By which I mean studies done on people who had already had a heart attack or stroke, or suchlike and were at great risk of having a ‘second’ event. So these were very high risk people, where the benefits of statins would be at their greatest.
Looking at the Heart Protection Study (HPS) done in the UK, we used a technique for analysing survival time called RMST (restricted mean survival time). I won’t go into the details. The HPS study lasted for five years, and we calculated that the average increase in survival time was 15.6 days. This was at the end of five years of treatment (with a confidence interval of 5 days either side). For 4S, the figure was 17 days.
Framing this slightly differently, what this meant was that taking a statin for one year, in the highest risk group possible, would increase your life expectancy by around three days. We thought that people should know this. Unfortunately, the BMJ thought otherwise. Such is life.
However, more recently the BMJ did decided to publish another paper entitled: ‘The effect of statins on average survival in randomised trials, an analysis of end point postponement1.’ They used slightly different mathematical techniques, including the ‘quick method.’ To quote:
‘We also calculated all areas in a less technical manner, that is, by drawing one or more triangles by hand on magnified paper prints of the survival curve for each study and then calculating the areas of these triangles by standard arithmetic. This is referred to as the quick method.’
I have to admit that’s my kind of maths. Get out the pencils and draw it all out by hand. They also looked at more studies than we did, and aggregated them. Which has benefits and disadvantages. Sometimes you are not comparing like with like. However, the main results of their study, and their conclusions, were as follows:
Results: 6 studies for primary prevention and 5 for secondary prevention with a follow-up between 2.0 and 6.1 years were identified. Death was postponed between −5 and 19 days in primary prevention trials and between −10 and 27 days in secondary prevention trials. The median postponement of death for primary and secondary prevention trials were 3.2 and 4.1 days, respectively.
Conclusions: Statin treatment results in a surprisingly small average gain in overall survival within the trials’ running time. For patients whose life expectancy is limited or who have adverse effects of treatment, withholding statin therapy should be considered
Overall their findings were far less impressive, even, than ours. They calculated, approximately, a single day of increase in life expectancy for each year of taking a statin. Slightly more in secondary prevention, slightly less in primary (people who have not previously had a heart attack or a stroke).
The main take away message I believe, is the following. Statins do not prevent fatal heart attacks and strokes. They can only delay them. They delay them by about one or two days per year of treatment. For those who have read my books you will know that I have regularly suggested we get rid of the concept of ‘preventative medicine’. We need to replace it with the concept of ‘delayative medicine’.
You cannot stop people dying. You can only make them live longer. How much longer is the key question. With statins this question has been answered. You can, to be generous, add a maximum of two days per year to life expectancy.
Which means that if you were to take a statin for thirty years you could expect to live about two months longer. (Possibly three, more likely one). Assuming, and this is a big assumption, that none of the trials done have been in any way biased towards statins. Even though every single one was funded by the pharmaceutical industry. Further assuming that any benefits seen in the trials will continue for the next twenty-five years.
Why, you may ask, has the pharmaceutical industry never chosen to present the results of the statin trials in this way? In truth that is a bit of a silly question. I think anyone with a half functioning brain knows why the pharmaceutical industry has never chosen to present the result of the statin trials in this way. A 36% reduction in fatal heart attacks does sound rather better than, one extra day of life for every year you take a statin – best case scenario in primary prevention… Does it not?
1: Kristensen ML, et al. BMJ Open 2015;5:e007118. doi:10.1136/bmjopen-2014-007118