The Libin Cardiovascular Institute of Alberta’s Dr. William Ghali wrote an editorial for the February 16th 2009 edition of the BMJ. Have a read:
HDL cholesterol and cardiovascular risk
Treatments can increase HDL cholesterol, but do not independently reduce risk
History tends to repeat itself, in the medical sciences as in other domains. In the linked systematic review (doi:10.1136/bmj.b92), Briel and colleagues put high density lipoprotein (HDL) cholesterol into perspective as a marker of risk, and their findings evoke memories of other risk markers.1 Like HDL cholesterol, premature ventricular contractions are a validated risk marker for cardiovascular disease. Such contractions indicate an increased risk for adverse cardiovascular outcomes in the general population and in patients presenting with cardiovascular disease.2 3 Yet specific treatments that eliminate these contractions do not decrease the risk for adverse outcomes and can even increase risk.4 Thus, modifying the known marker of increased risk does not necessarily modify the risk itself.
Briel and colleagues demonstrate this phenomenon for HDL cholesterol in a meta-regression study of 108 clinical trials that assessed more than 300 000 patients and several lipid modifying treatments.1 They found that …
Read the rest on the BMJ web-site.