The Vytorin kerfuffle has receded to a slow burn, but that hasn’t stopped the disease management blog from mulling over what can be learned about the population-based dimensions of lipid management.
First some lipid orthodoxy, then the stuff of head cramps and then some discussion of a potentially under recognized ingredient in the Vytorin saga. If you’re already familiar with statins and lipids move 4 paragraphs down.
There is a direct link between blood cholesterol levels and the later development of atherosclerosis. Statins block the body’s ability to manufacture cholesterol. Multi-year studies involving statins have shown they lower cholesterol, reduce the progression of astherosclerosis, decrease the incidence of heart attack and save lives.
In general, there is a correlation between the amount of statin taken, the degree of blood cholesterol lowering and the subsequent risk of atherosclerosis-related diseases like heart attack. The more you take, the better the risk reduction for heart attack. But here is the rub: not everyone responds to statins the same way and some individuals taking statins still get heart attacks. According to one reference, a maximum dose of one statin will result in about only 70% of adults having the kind of low blood cholesterol level that in turn correlates the greatest reduction in heart attacks. The remaining 30% have a lower risk, but it’s not optimum.
Enter ezetimibe. This is a new agent that works differently than statins. It blocks the absorption of dietary cholesterol. While taking it leads to decreases in blood cholesterol, there are no studies (unlike statins) proving that the lower blood cholesterol from ezetimibe in turn leads to a lower frequency of heart attacks. However, based on what we know about blood cholesterol, it’s not unreasonable to believe that it could but there is no proof. Hence its potential role for the 30% of persons for whom statins are not enough.
The tension between populations and individuals is what gives the disease management blog a head cramp: if a population has a high frequency of cholesterol testing and statin usage, or (even better) if blood cholesterol levels are dropping thanks to statin use, you can confidently predict that the frequency of heart attacks will go down. Some individuals on statins, however, will still get heart attacks, just like some individuals on blood pressure medicines will still have high blood pressure. It's not unusual for physicians to struggle with reconciling that lower individual risk when making treatment decisions.
Why the head cramp you ask? There isn’t a managed care organization (MCO) seeking accreditation with the National Committee for Quality Assurance (NCQA) that isn’t doing its best to reduce the number of persons at risk for a heart attack using HEDIS measurements of cholesterol levels. While there are interventions that increase measurement rates and lower cholesterol levels at a “population” level, MCOs typically apply their maximum leverage at the individual patient-physician level, using what can euphemistically be called feedback and incentives. The result? Since physicians can easily recall that last statin-taking heart attack victim and 30% of their patients don’t get to target cholesterol levels anyway, the additional MCO leverage lowers the threshold for them to prescribe ezetimibe, even though the lower cholesterol has only a potential role in the reduction of heart attacks.
Enter the ENHANCE trial. Even though ezetimibe lowers blood cholesterol, this study used something completely different and more meaningful: thickening in the inside of the carotid arteries. This is a surrogate marker for the development of atherosclerosis, which is a arguably a stronger predictor for heart attack risk than a cholesterol level. Compared to statin alone, the addition of ezetimibe (combining ezetimibe with a statin in one pill is called “Vytorin”) - even though cholesterol levels were lower – had no impact on the progression of atherosclerosis. That means it’s less likely have any impact on heart attacks or saving lives.
The disease management blog speculates that at least some of Vytorin's growth was powered by physicians being leveraged by MCOs that were less interested in meaningful population-based improvements like heart attack reduction and more interested in their shorter term HEDIS rates. There is no proof of course, but if you ask a typical PCP, you might get a yes. Ask me and I will say yes. Ask NCQA and they will take credit for post-MI beta blocker prescribing: why not let their participants share some of the credit for Vytorin with Merck and Schering Plough?? Pending proof (which may still come) that Vytorin prevents heart attacks, a rigorous population-based approach would be to not give any credit for cholesterol lowering thanks to this drug. There are also implications for the physician feedback and incentives described above.
Even though statins reduce heart attack risk, it doesn’t have a 100% success rate. Compared to other interventions, however, it has a very good track record and lots of statin prescribing is good. Measurement of this at a population level is meaningful.
Considering the potential role of ezetimibe from a population perspective makes it a heluva lot easier to discern what it is known to do (lower cholesterol) and what it isn’t known to do (prevent heart attacks).
MCOs' running amok by leveraging NCQA HEDIS at the individual patient-physician level, where the benefit of statins are less readily discernible, may lead to short term measurement improvements (lower cholesterol). The potential price is the use of unproven treatments like Vytorin with no evidence from a population perspective that anyone is benefiting.
And here’s the punchline: ever wonder why disease management organizations are not more intimately involved in their customers’ HEDIS improvement activities? The disease management blog thinks that these companies – thanks to risk corridors that place a premium on hard money outcomes at a population level – understand the role of HEDIS. Good disease management leads to better clinical outcomes and better HEDIS rates. Improving HEDIS rates does not necessarily mean good disease management.