Why don’t we just put statins in the water supply and be done with it?

Statins and the risk of colorectal cancer in last week’s NEJM is a case-control study from Israel that looked at about 2000 patients with colorectal cancer and a similar number of controls, and found that “the use of statins for at least five years (vs. the nonuse of statins) was associated with a significantly reduced relative risk of colorectal cancer”. The odds ratio was about 0.50.

At the risk of sounding like a broken record, this is yet another case-control study, useful as hypothesis generating, but not much else. The authors performed their analysis adjusting for multiple co-variates, such as aspirin use, vegetable consumption, red-meat consumption, but there is no way they can sufficiently adjust for all variables to convince me.

For one thing, they don’t mention adjusting for low-saturated fat diets which patients who take statins are likely to adhere to. And there are sure to be other confounders associated with statin treatment.

The one fact that almost convinced me was that the authors found no protective effect from non-statin cholesterol lowering agents (fibrates). These are likely to be associated with most of the same confounders as statins. BUT, there were only 20 patients taking these drugs, too few to be statistically reassuring, and the reason for prescribing a fibrate rather than a statin is more likely to be hypertriglyceridemia than hypercholesterolemia, implying a different population and perhaps a different diet as well.

Medpundit is also critical of this study. I have to disagree with her main argument against it, however. She feels that the biggest flaw is that the two groups were not matched for ethnicity, with a higher percentage of Ashkenazi Jews in the cancer group. However, in their adjusted analysis, the authors specifically state that they adjusted for ethnicity. In my opinion, the biggest problem with case-control studies is not that they do not adequately adjust for known confounders, but rather that they don’t take into account confounders they have not thought of.

3 thoughts on “Why don’t we just put statins in the water supply and be done with it?

  1. Clinical Cases and Images

    This new study adds more to the Polypill concept published in BMJ in 2003 – everybody over 50 should be on ABCDE (ASA, Beta blocker, Cholesterol lowering statin, Diuretic, Enzyme inhibitor – ACEi, and Folate).

    Estrogen HRT was looking promising for a number of indications before the large RCTs were done. And then we had to call all our female patients to stop the “magic pill”.

    This is the Tamhane’s law (named after one of my colleagues): a new study is out and then the doctors run in its direction as fast as they can, prescribing the new drug left and right, Then, several years later, another new study shows no benefit or even harm. Then, the doctors run just as fast in the opposite direction. (Have a mental picture of a flock of sheep).

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