|The Percival Effect
Ben Wolozin did it again. Whenever he and his colleagues turn to statins and epidemiology something unexpected happens. The data by themselves are stunning. Stunning because of the enormous sample size, stunning because of the extreme risk reduction in the simvastatin population, stunning because of the unexpected PD effect (maybe not as much unexpected to those who listened to Eliezer Masliah's talk in Salzburg). Moreover, the work shows how urgently more studies are needed to explore and validate these effects within prospective clinical trials—studies aimed to explore and validate the modes of action of statins in dementia, and studies that compare the effectiveness of different statins.
But the vast sample size came at a cost. Predominantly, the absence of a good control group, the increased likelihood of bias (because the database used does not reflect an average U.S.-American population), and missing resolution when it comes to the details.
One example that highlights this is the cardiovascular risk group (CV). Statins are given to...