Two years after their “thumbs up” to statins, The Cochrane Collaboration revised their data and came to starkly different conclusions. The group did another meta-analysis, using four additional trials. These trials did not offer much, if any, evidence to urge the authors to deviate from their 2011 conclusions.
As Dr. John Briffa reports: “In 2013, the same Cochrane group updated their data and concluded that overall 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).”
What explains this about-face? Cochrane included data from another meta-analysis, Cholesterol Treatment Trialists’ (CTT) Collaboration, published in 2012. As Dr. Briffa notes, this analysis found that “statins have significant benefits in low risk individuals that greatly exceeded known risks of treatment.”
Very well then. Perhaps the 2011 Cochrane report was overly skeptical and cautious.
However, Dr. Briffa challenges this conclusion: “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 relevant appraisal would be simply to calculate if, compared to placebo, statins actually reduce the risk of health outcomes.” In other words, the CTT authors used statistical slight of hand, not actual science, to come to their conclusions. The Cochrane authors sloppily accepted this bad science and incorporated it into their analysis.
Critics of the Cochrane and CTT analyses lashed out at this sloppy science in the British Medical Journal (BMJ) in 2013. Dr. Briffa summarizes what they said: “the BMJ authors used the data from the CTT meta-analysis and found that risk of death was not reduced by statins at all. So, the CTT authors had extrapolated the data in a way that showed a benefit that actually does not exist in reality.”
Briffa continues: “They also draw your 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 judgment regarding the overall effects 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 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 for overall benefit.”
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