Saturday, June 4, 2011

What to do about Niacin?

I have been getting a lot of questions regarding the use of Niacin since the media recently reported that the NIH had stopped their AIM-HIGH study. AIM-HIGH was designed to see if adding Niacin to patients on a statin who still had low HDL and high triglycerides would improve cardiovascular outcomes (heart attacks, strokes). Though we know that high triglycerides and low HDL are both strongly associated with heart disease, that Niacin will raise HDL and lower triglycerides and even few early studies did show raising the HDL with Niacin did work; this large, randomized NIH sponsored showed no evidence of improvement.  Though the actual data from the study has not been released, we do know that the NIH stopped the study a year early because there was no benefit seen and possibly some harm in the form of excess stroke.  One possibility is that patients were taking statins at doses that lowered their LDL to very aggressive levels (target range of 40-80). Some have postulated that with an LDL that low, you will never get a heart attack or stroke.  So, Niacin may indeed work, but not with super reductions of LDL's with statins.

One of the main points of from these findings is that we have to be careful when it comes to using surrogate endpoints (like LDL and HDL) for treatment.  For example, lowering the LDL with a statin reduces heart attacks and strokes. However, lowering the LDL with ezetimibe (Zetia) doesn't seem to do this (see here for more details)  This might be the case for Niacin and HDL as well. 

I have never been a big fan of Niacin because it causes pretty bad flushing, increases uric acid/gout, and most importantly raises blood glucose.  Most of my patients are diabetic/prediabetic, so raising their blood sugar is not something I am too fond of.  The other drugs that can raise HDL and lower triglycerides are fibrates. Gemfibrozil has clearly demonstrated this in a large VA study (VA-HIT).  The problem with gemfibrozil is that it can interact with statins, causing some serious side effects.  Statins are the one med that clearly works in just about everyone with increased cardiac risk.  Fenofibrate works the same way, but can be used safely with a statin.  However, when they tried to demonstrate cardiovascular improvements with fenofibrate (FIELD study), the primary outcome was not statistically significant.  One of the differences between VA-HIT and FIELD is that more patients were on statins in FIELD, since FIELD was a more recent study and regular use of statins had become standard of care.  However, in the diabetic patients with low HDL and high triglycerides, the FIELD study did show that fenofibrate reduced heart attacks and strokes. The ACCORD lipid study (another large, randomized, NIH sponsored trial), attempted to prove benefit by adding fenofibrate to all diabetics on a statin, but failed.  However, similar to FIELD, in those diabetics with low HDL and high triglycerides, fenofibrate added to a statin did reduce heart attacks and strokes. The consistency of these findings therefore have some merit. 

Bottom Line: Statins remain the first choice for patients at increased cardiovascular risk and should be used at doses that meet individual LDL goals and/or lower LDL by 30-40%.  After that, the rationale for treating low HDL/high trigs is now less clear. Before we see the actual data from the AIM-HIGH study, it would be premature to pull all patients off of Niacin.  That being said, in my opinion, Niacin's days are likely numbered.  Evidence for raising HDL and lowering triglycerides seems to be much stronger for fenofibrate, at least in diabetics, and fenofibrate does not seem to have the negative effects, specifically hyperglycemia, seen with Niacin. 

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