Coronary Heart Disease & Statins Controversy (Part III) – Blog Post by Asrar Qureshi
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Continued
from Previous……
Controversy about Statins
Most
information, and excerpts, for this part have been taken from the published
article ‘Cholesterol confusion and statin controversy’ DuBroff R, de Lorgeril M. Cholesterol confusion and statin
controversy. World J Cardiol 2015; 7(7): 404-4091
Since
the statins were introduced more than twenty years ago, the case for use of
statins has been consistently built up through various clinical trials. The
first major study, the 4S study demonstrated that the use of a
cholesterol-lowering statin reduced mortality by 30%. Several more studies have
been published later elucidating the efficacy and safety of statins. The USFDA
has issued warnings about increased risk of diabetes and decreased cognition.
More importantly, studies on the relationship between cholesterol and ischemic
heart disease have not been able to show conclusively that the two have cause
and effect relationship and that lowering cholesterol will reduce mortality due
to heart disease or even all-cause mortality.
Statins
are among the top revenue generating products all over the world.
Pharmaceutical industry therefore has a direct, intense interest to keep
statins in news. More clinical studies are sponsored, published and presented
at clinical forums; patient awareness campaigns focusing on cholesterol and
heart disease are run; screening camps are arranged for prospective high cholesterol
people who could become candidate for statin prescription.
We
look at the associated facts more closely.
Relationship/ Association of Cholesterol
with Cardiovascular Disease
The
cholesterol theory aims to establish a link between cholesterol intake and
blood levels with development of cardiovascular disease. Cholesterol is
considered a risk factor for atherosclerosis and lowering cholesterol in the
blood may be seen as the best way to prevent heart disease. However, risk
factors do not affect everyone the same way and ideally, it should be
distinguished
as to who will or will not develop a disease. From the original
Framingham Heart Study Data shows that the cholesterol levels of those who
developed coronary heart disease and those who did not, were similar except
when the total cholesterol level exceeded 380mg/dL or was less than 150mg/dL.
Moreover, while cholesterol may be associated with coronary heart disease (CHD)
but that does not prove that it actually causes it. Another important fact is
that the studies designed to raise HDL (High Density Lipoprotein) or lower triglycerides
have failed to reduce CHD mortality. Whether cholesterol control should become
automatically become a treatment target, is under debate.
The
rare incidence of CHD in isolated, rural societies such as Tukisenta, New
Guinea has been attributed to low cholesterol levels. However, it is equally
plausible that the diets and lifestyles of these individuals may protect from
CHD. While we may never be certain about this, there is ample evidence that
lowering cholesterol does not consistently lower CHD mortality. It is also
recommended that the intake of dietary saturated fatty acids should be
restricted in order to lower cholesterol levels in blood. However, an
exhaustive review and meta-analysis of 72 dietary studies concluded that
reduced consumption of saturated fat does not reduce cardiovascular mortality.
Many drugs such as niacin, fibrates and bile-acid sequestrants can lower
cholesterol levels, but the recent AHA/ACC guidelines on cholesterol concluded
that these do not lower CHD mortality rates. Similarly, the results of
cholesterol-lowering statins trials demonstrate that the statins do not
consistently lower mortality rates.
Why
then there has been so much hype about statins?
Early
statin trials reported significant mortality benefits, yet serious concerns
have been raised in some studies regarding biased results, premature trial
terminations, under-reporting of adverse events, high numbers of patients lost
to follow up, and oversight by pharmaceutical company sponsor. Heightened
awareness within the scientific community regarding problems in clinical trial
conduct and analysis – exemplified by the unreported risk of heart attacks in
patients taking the pain-killers Vioxx (rofecoxib – later withdrawn) and
Celebrex (celecoxib – still selling), led to new regulatory rules for clinical
trials in 2005. It is curious to note that statin trials conducted after 2005
have failed to demonstrate consistent mortality benefit.
References.
Continued……
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