Wednesday, January 26, 2011

Cochrane Review: Statins in Low-Risk Patient Populations

Dr. Steven Novella recently posted about a Cochrane review of statins (cholesterol-lowering drugs) on SBM.  As Dr. Novella says, the question is not about whether or not statins work (they do), but whether or not their use is warranted in low-risk populations.  The Cochrane review found that 1000 low-risk patients would need to be treated in order to prevent one death per year from a cardiovascular event.  10+ million people in the US are on a statin, but I'm not sure how many of them are at a low risk of having a cardiovascular event.

At the end of his post, Dr. Novella wonders what the cost breakdown would be for something like this.  How much money is spent on the statins versus how much would have been spent on the cardiovascular events the drug helped patients avoid?  I decided to make a few quick calculations just to see what kind of ballpark figures we're looking at.  With all the talk about rising healthcare costs, I thought this would be worth looking into.  This is by no means conclusive, and like I said, I don't know how many low-risk patients are taking statins.  This is more of an intellectual exercise, as I'd expect someone with greater access to statistics concerning statin use to be able to come up with a much more accurate figure.  But I'll give it a shot anyway because I'm bored and I don't feel like studying for my exams on Monday (which, coincidentally, are over cardiology!).

First, let's look at some of the relevant costs and statistics:
  • Statin (e.g. Lipitor) prescription:  $140/mo (per Epocrates), or ~$1,700/yr
  • Acute Myocardial Infarction (Heart Attack) Treatment costs (direct):  $9,200 (in the US)
  • Stroke treatment costs (direct):  $15,000
  • CHD events, no treatment:  (918/14,011) = 6.552 %
  • CHD events, statin:  (659/13,958) = 4.721 %
  • Stroke events, no treatment:  (253/10,802) = 2.342 %
  • Stroke events, statin:  (197/10,754) = 1.832 %

Now, the problem that I have here is that I don't know how many people taking statins are at a low risk of having a cardiovascular event.   If I find somewhere to get that information, I'll be sure to update this article, but in the meantime, let's just say that 1 million of the people taking a statin are at a low risk (that's <10%).  Some statistics based on that assumption:
  • CHD events, no treatment:  65,520
    • Cost =  $602.8 million
  • CHD events, statin:  47,210
    • Cost = $434.3 million
  • Stroke events, no treatment:  23,420
    • Cost = $351.3 million
  • Stroke events, statin:  18,320
    • Cost = $274.8 million
  • Statin cost:  $1.7 billion
  • Lives saved:  1,000
  • Cost per life saved = Cost of Statin - Saved cost of CHD & stroke events = ($1,700 million - $245 million)/1,000 people = $1.46 million per life saved

Now, this cost-benefit analysis leaves many factors out.  Among them:
  • The costs shown are only "direct" costs of inpatient care (hospital stay, health care personnel fees, equipment use, etc.).  Indirect costs include other things like the cost of lost work/productivity for the patient, ongoing care, and additional prescriptions (e.g. an anticoagulant prescribed after a patient experiences an MI).
  • I'm not sure how many statin users are actually at low risk of having a cardiovascular event.  My 1 million figure was just to make the discussion easier, but I honestly have no idea what the actual figure is.
  • CHD events and stroke aren't the only costly results of cardiovascular disease that are reduced by statin use.  Other cardiovascular events may occur that have additional direct and indirect costs associated with them.
  • Some statins are going off-patent soon.  Lipitor, the statin used in this example, will be available off-patent at the end of the year.  This will drastically reduce the cost of the drug.  Zocor, another statin that is now off-patent (i.e. available as a "generic") costs $160/mo whereas the generic version is only $28/mo (according to Epocrates) -- an 82.5% savings!  You wouldn't even need everyone to switch to the generic version of Lipitor and you'd still see that cost per life saved go WAY down!

Considering the limitations of my "analysis", I wouldn't be surprised if the cost per life saved were significantly lower than calculated.  With indirect costs included, it might even be an overall savings, especially once more people switch to generic versions of these drugs!

Of course, when discussing the use of the drug, I'm not saying that the "cost per life saved" should be the chief factor governing use.  But given the state of healthcare, it's something that should at least be brought up during the discussion.  Also, when discussing medications, it's important to keep in mind the change in the absolute risk of a disease/event.  For example, Lipitor decreased the relative risk of having a CHD event by 28% in these studies, but in absolute terms, that risk was decreased from 6.6% to 4.7%.  It is a decrease, certainly, but one that must be put into context when talking about a "28% decrease" in risk!

As Dr. Novella discusses on SBM, the study isn't about whether or not statins are effective -- they're very effective in reducing cardiovascular events in high risk patients!  Rather, the data should lead us to ask ourselves whether or not it's worth $1700/yr to go from a 6.6% to a 4.7% risk of having a CHD event for a low-risk patient.  Considering the other costs involved with having any sort of cardiovascular event, and the number of lives saved, I think in general it's a good route to take.  Even so, there are other life-style changes that could be just as effective -- salt and fat restriction, diet and exercise improvements, etc.  In the end, the decision to go on a statin should be a decision made between the doctor and patient after considering the benefits, costs, risks, and alternatives to pharmacological treatment.

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