Wednesday, February 6, 2013

Do heart patients have high cholesterol?

We always hear from our doctors how high cholesterol will cause you to get heart disease. This would imply that people getting into hospitals due to heart disease, would have a high cholesterol. I would have thought that this would be the first thing to test. But the medical world works in mysterious ways.

There has been a 2008 paper where the cholesterol values of the people entering hospitals due to heart disease was collected. These people collected data from 1,36,905 hospitalizations. Luckily the paper is freely available online. Following is the most interesting image from the paper.

We can see by extrapolating from the bars, that about 50% of the people have the following ranges of Cholesterol values. Unfortunately they did not do men and women separately, as another paper has shown that cholesterol response varies a lot between men and women. I have written an article on the paper.

LDL - 75-125
HDL - 30-45
Triglycerides - 80-160

They did not measure VLDL, which is normally tracks Triglycerides.

Now one can see that the cholesterol is perfectly within guidelines given by the Doctors. The HDL is a bit lower. The paper also noted this fact but then recommended that the guidelines need to be lowered. This makes no sense, because they have not yet established that people without heart disease have lower cholesterol.

Following is an attempt to find cholesterol data for all american people, not just stricken with heart disease.

I searched for American research papers or data giving a similar graph for normal people. Unfortunately, I cannot find anything recent. The closest we have is the data from 1976-80. I also found data from 1971-74, and 1960-62. The govt has stopped collecting the data in this format. I wonder why :-). The same problem is with the BHF heart stats from UK. Unfortunately the only data which we can use is the first one, as the other two do not give the data for all adults, they segregate it into males and females. Also we want the most recent data, so we will look at the 1976-80 data.

So lets see how the data looks like. Again the range of cholesterol for 50% of the population.
TC - 179-239
HDL - 37-51
Non-HDL - 131-195
Triglycerides - 84-168

There are not too many points of comparison. Triglycerides are very similar. HDL levels are quite a bit lower in the people with heart disease. Non-HDL includes LDL and VLDL. VLDL is normally a very small number, and is directly dependent on the Triglycerides. Even if we remove a small amount for the VLDL, we still have a very low values for LDL cholesterol in the people with heart disease. Now it is also possible, that LDL has reduced for all the people, due to the dietary measures applied by the normal public. Unfortunately we cannot compare newer numbers, as the govts do not measure the current distribution of cholesterol. The numbers they collect are pretty useless for making any inferences.

If the LDL numbers have really dropped so drastically, we should see a large drop in heart disease incidence, because of the reduced LDL. Unfortunately, that is not the case.

We can see that the incidence of heart disease has remained nearly same, since 1980, from when we see the data. The mortality has reduced but that is probably due to better patient care and new surgical methods and technologies. Some of the rise in the incidence can also be attributed to better diagnosis.

Unfortunately, lack of recent data makes it difficult to have a proper conclusion. But the available data is not positive for the current cholesterol hypothesis.

1 comment:

  1. It is also true that a low cholesterol and low saturated fat diet can also give high Cholesterol level. My vegetarian friend was taking statin to reduce cholesterol.