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Statins effects: benefits
For the specific benefits of statin drugs, we need to turn to the only source we have: clinical trials and statistical studies. According to one large statistical study on the effects of statin drugs (Vrecer et al., International Journal of Clinical Pharmacology and Therapeutics, 12/2003), which used the data from 16 statin studies ranging from 1985 to 2002, with over 63,000 total participants (58 years of age average, 21% woman), statin drugs - simvastatin (Zocor), pravastatin (Pravachol) and lovastatin (Mevacor) - cause fairly consistent reduction in blood levels of "bad" cholesterol (29%) and triglycerides (12%), while also slightly elevating "good" cholesterol (6%).
Since there is no known mechanism with which statins affect triglycerides directly, their reduction may be result of statins having some antioxidant properties. Out of seven studies that have measured triglycerides, six are small, but all of them have triglycerides reduced in the statin group, and elevated in the placebo group. This also suggest a possible pattern in which placebo group have larger proportion of folks on high sugar/fat diets.
effect on cardiovascular disease? Numbers in the table below
indicate that, according to study data, statins reduce the risk of major coronary event
and coronary death roughly 30% in both, primary and secondary
prevention treatment. Effect on the risk from stroke and
non-cardiovascular death is small or negligible. The
Needed to Treat) indicates how many people need to be treated in
order to have a single specific - in this case positive -
Statistical results for primary (patients w/o symptoms of cardiovascular disease) and secondary prevention (patients with existing cardiovascular disease) statin treatment. Primary prevention results are from the Vrecer statistical study (based on four direct studies, 7290 patients on statins, 7267 on placebo, 4.8 years average treatment duration), and those for secondary prevention is obtained from the data for the three studies (8814 patients on statins, 8803 on placebo, 5.7 years average treatment duration) classified as such in the Vrecer study. *NNT=100/(%S-%P)
Taking a closer look, we can say that the numbers for coronary death in the primary prevention, as well as those for stroke, are statistically unreliable due to their low incidence level, combined with relatively small sample size. This is clearly indicated by discrepancies between the studies. For instance, the rate of coronary deaths in the Scandinavian Simvastatin Survival Study is 70% higher in the placebo group, while in the Cholesterol and Recurrent Events Study it is only 24% higher (both studies were for the secondary prevention treatment, same mean age, similar treatment length and generally similar level of risk factors; the only difference is that the latter study used pravastain).
Also, stroke incidence is higher in these two studies for the placebo group, 39% and 45%, respectively, while 23% lower in the third secondary prevention study (LIPID study, pravastatin).
Likewise, the incidence of major coronary event for woman is 70% higher in the placebo group in the Cholesterol and Recurrent Events Study, while only 15% so in the LIPID study (with more than double the number of participants). Statistically insufficient sample size is even more pronounced with women, who make about 1/6 of the participants. For some reason, researchers seem to tend to neglect this fact, extract the average and plainly state that, say, statins work for woman as well.
These discrepancies may also result from not making sure that the overall health - including all cardiovascular risk factors - is similar in both, treatment and placebo group, the manner in which the studies were conducted, or something else. For instance, drop-outs, mostly due to side effects, are commonly ~20%, on average, with statin users; this gradually diminishes the size of statin group, and with it the total of cardiovascular problems recorded.
On the other hand, compliance is also, for the same reason (side effects), generally lower in the statin group which, in effect, lowers the actual dose, as well as the actual number of statin users.
Were these - and other - factors always properly factored in? No one can tell. What regularly isn't monitored, and should be, is nutritional status - in particular that for the major antioxidant nutrients - of the participants. It can make significant impact on the results. A large, quality, truly independent direct study of statin effects would take into account all relevant factors. Unfortunately, no such study has been produced thus far.
What is much less uncertain than benefits are the adverse side effects caused by statins.
Side effects of statins