Two new research papers add more fuel to the never-ending debates about cholesterol and cardiovascular disease. You would think that after decades of intensive global study and the use of truckloads of cholesterol-lowering drugs by millions of patients, we'd be able to settle this.
At the heart of the controversy (yes, purposeful use of “heart”) is something most doctors and patients take as gospel: Lower cholesterol = lower risk of heart problems. This, in a highly simplified form, is what's called the “cholesterol hypothesis.” It sits at the center of modern preventive heart care, has launched a thousand low-fat diets, has made cholesterol-lowering statins into the best-selling drugs in history . . . and is looking more and more questionable.
The JAMA piece tracked more than 31,000 patients who were taking statins, comparing outcomes to LDL-C levels (low-density lipoprotein cholesterol – the infamous “bad cholesterol” doctors focus on in blood tests). To their surprise, they found that patients who were getting their LDL-C down to the lowest levels – below 70mg/dL, the target for many statin regimens – did no better than patients who only got them down between 70 and 100. Anything below about 90 seemed to do nothing to prevent heart attacks. Lower was not necessarily better. A strike against the cholesterol hypothesis.
The BMJ Open paper went the next step. A systematic review of existing studies led authors to the conclusion that lower LDL-C not only didn't seem to do much to lower all-cause mortality in patients over 60 years of age, but might actually be bad for older patients. As LDL-C levels went down, cardiovascular mortality went up. “This finding is inconsistent with the cholesterol hypothesis,” the authors, with notable understatement, concluded. “Since elderly people with high LDL-C live as long or longer than those with low LDL-C, our analysis provides reason to question the validity of the cholesterol hypothesis.” Strike two.
Both studies are already being raked over the coals. There is a lot of money at play around the cholesterol hypothesis, there are plenty of counter-studies that show that lowering cholesterol goes along with lower risks of heart disease, and no amount of new research seems to solve the issue.
But the fact that decades of study leave us here does make you wonder – not only about the cholesterol hypothesis, but about the ability of “evidence-based medicine” to come to definitive conclusions when the benefits are small and the stakes are high.