Comment by carbocation

Absolutely. In fact, because statins have such a powerful effect on cholesterol, there is a good chance that a bunch of the people in the low cholesterol strata are taking statins. So, at the risk of being a broken record in this thread, these results are likely to be confounded by indication. That is, the low-cholesterol groups are enriched for people who have low cholesterol because they are taking statins. And they are taking statins because a physician has deemed them to be at elevated risk of disease (or already have disease), and are thus more likely to die.