The ‘Cochrane Collaboration’ is an international collective of researchers whose self-proclaimed role is to provide accurate and robust assessments of health interventions. The group specialises in ‘meta-analyses’: the grouping together of several similar studies on interventions including drug therapies.
In 2011, Cochrane researchers assessed the evidence relating to statin use in individuals at low risk of cardiovascular disease (defined as a less than 20 per cent risk over 10 years), and concluded that there was limited evidence of overall benefit . I appeared on Channel 4 news to discuss this publication and the issues surrounding it, and you can see the discussion here.
Earlier this year, the same Cochrane group updated their data and concluded thatoverall risk of death and cardiovascular events (e.g. heart attack or stroke) were reduced by statins in low risk individuals, without increasing the risk of adverse events (including muscle, liver and kidney damage) . It seems the Cochrane reviewers had had quite some change of heart. A paper published in the BMJ on 22 October questions the evidence on which this U-turn appears to have been made .
The authors of the BMJ piece note that although the 2013 meta-analysis included four additional trials, these trials did not substantially change the findings. The change in advice was actually based on another meta-analysis, published in 2012, conducted by a group known as the Cholesterol Treatment Trialists’ (CTT) collaboration .
Among other things, the CTT authors concluded that, in low risk individuals, for each 1.0 mmol/l (39 mg/dl) reduction in LDL-cholesterol, statins reduce overall risk of death and heart attack by about 9 per cent and 20 per cent respectively. The conclusion was that statins have significant benefits in low risk individuals that greatly exceeded known risks of treatment.
However, the CTT authors took the odd step of calculating the benefits of statins according to a theoretical reduction in LDL-cholesterol levels. A much more realistic appraisal would be simply to calculate if, compared to placebo, statins actually reduce the risk of health outcomes.
The BMJ authors use the data from the CTT meta-analysis and found thatrisk of death was not reduced by statins at all. So, the CTT authors had used had extrapolated the data in a way that showed a benefit that actually does not exist in reality.
And what of the claim that statins reduce the risk of cardiovascular events such as heart attack or stroke? The data shows that about 150 low-risk individuals would need to be treated for five years to prevent one such event (i.e. only about one in 750 individuals will benefit per year).
They also draw our attention to the impact of statin treatment on ‘serious adverse events’. This outcome can be improved by statins as a result of, say, a reduced number of heart attacks, but worsened through side effects such as muscle or liver damage. The BMJ authors note that the CTT review did not consider serious adverse events (a major omission). Without knowing more about this, though, we simply cannot make a judgement regarding the overall effect of statins, and whether the net effect is beneficial or not. Interestingly, of three major trials that were included in the CTT review that assessed overall serious adverse effects, none found overall benefits from statin treatment.
So, while the CTT authors seem to have over-hyped the benefits of statins, they seem at the same time to have been quite keen to steer clear of talk of their very real risks and the absence of evidence foroverall benefit.
The BMJ authors draw our attention to the fact that every single trial included in the CTT was industry funded. Such trials are well known to report results more favourably and perhaps downplay risks than independently funded research. The BMJ authors cite specific ways in which the adverse effects of drugs seen in clinical trials can be ‘minimised’. These include:
- The exclusion of individuals from trials with known health issues likely to be exacerbated by statins or signal susceptibility to statin side effects (such as liver, kidney and muscle disease).
- The use of a ‘run-in’ period before the study starts which detects and then excludes individuals who do not tolerate statins.
- The possibility that individuals ‘drop out’ from the study because of side effects, meaning that the incidence of some side effects can be ‘lost’ from the data.
- Failure of the study investigators to assess and monitor adverse events such as muscle damage and changes in brain function.
- Failure to properly ascertain or report adverse events.
It is noted that the Cochrane authors admit the reporting of adverse effects in studies is generally poor, but also state that it’s unlikely statins have major life-threatening hazards. The authors of the BMJ piece are not convinced, though, writing: “[The] large discrepancies between the frequency of adverse events reported in commercially funded randomised controlled trials included in the CTT meta-analysesand non-commercially funded studies show that determination of harms cannot be left to industry alone.”
The BMJ piece is accompanied by an editorial from the journal’s editor, Fiona Godlee . Her comment on this issue starts:
None of this does much to bolster confidence in the published literature.
Godlee goes on to write:
Nor am I reassured by discussions at two recent meetings co-hosted by the European Federation of Pharmaceutical Industry Associations (EFPIA). Drug company AbbVie is suing the European Medicines Agency to stop summary reports of its clinical trials becoming publicly available. AbbVie’s lawyer made clear that the company considers even the data on adverse events to be commercially confidential. Despite industry’s claims to be in favour of greater transparency, EFPIA and its American counterpart PhRMA are supporting Abbvie. The BMJ and BMA have joined forces to intervene on behalf of the EMA.
If I were to summarise, I’d say that, at best, there seems to be a degree of complacency regarding the veracity of statin data on the part of both the CTT and the Cochrane researchers. There is a sense that they are happy to present the ‘positive’ findings in the best possible light, and at the same time seem relaxed about the clear gaps we have in our knowledge about potential harms. The fact that statins appear to have no overall benefit in those at low risk of cardiovascular disease should not go unacknowledged, either.
Worse still, we have evidence that drug trials can be designed, conducted and reported in ways that obscure the truth. And sometimes, even when we have data that can help us make informed decisions about the appropriateness of a treatment, some drug companies will fight tooth and nail to prevent that data seeing the light of day.
This sort of subterfuge may be good for sales and share price, but it is almost certainly bad for our collective health. On this point, the BMJ authors state than instead of doctors following guidelines and prescribing statins for individuals at low risk of cardiovascular disease, they should explain the magnitude of benefits and uncertainties regarding harm. In addition, they might also discuss the fact that the vast majority of cardiovascular disease risk is linked with lifestyle factors such as smoking, diet and physical activity. Fiona Godlee backs this approach, but states that the benefits of lifestyle change are: “something that the dominance of industry sponsored clinical trials too often obscures.”
Personally, I am delighted that the misdeeds of drug companies and some researchers can now be exposed in this way, and in a high-profile medical journal at that. In the past, I think there was much more opportunity for the industry and its hired hands to mislead us. Greater transparency means that the industry as a whole is getting more of what I believe it deserves: our contempt.
1. Taylor F, et al. Statins for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev 2011;1:CD004816.
2. Taylor F, et al. Statins for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev2013;1:CD004816.
3. Abramson JD, et al. Should people at low risk of cardiovascular disease take a statin?
4. Cholesterol Treatment Trialists’ (CTT) Collaborators. The effects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials. The Lancet 2012;380(9841):581–90.
5. Godlee F. Statins for all over 50? No BMJ 2013;347:f6412.
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