Surrogate Outcomes and the Healthcare Consumer
December 20, 2016

Surrogate Outcomes and the Healthcare Consumer

Consider this question: If your lab report shows that you have high cholesterol, do you want a drug that will lower your cholesterol levels?

Here’s another: If you are diagnosed with diabetes, do you want to be prescribed a drug that will lower your blood sugar?

What about high blood pressure? Do you want a drug that will lower it?

These aren’t trick questions. But if they are starting to feel a little too obvious, you’re right. The answers aren’t obvious at all.

It’s not the high blood pressure, elevated blood sugar, or climbing cholesterol that bother you. Most people who are initially diagnosed with these issues are blissfully symptom-free. The consequences of these conditions – stroke, heart disease, kidney failure – are what truly affect your quality or length of life.

So, do you really care if your new cholesterol drug lowers your cholesterol? Or would you rather know that it reduces your risk of heart attack?

Sadly, we usually can’t answer that question for a new drug or treatment when it enters the market. Research that includes enough people and lasts long enough to answer the “real” questions takes a lot of money and a lot of time. Instead, researchers often rely on “surrogate markers.” Lowered blood pressure is viewed as a surrogate, or stand-in, for reducing strokes. Lowered blood sugar acts as a surrogate for reducing diabetic kidney disease.

It makes sense – if high blood sugar can lead to kidney failure, then lowering blood sugar should reduce that risk.

But the reality of the situation doesn’t always play out as expected. For example, cardiac arrhythmias often cause death after a heart attack, so the CAST trial looked at the use of some very effective anti-arrhythmic agents in that setting. The drugs fleicanide and encainide performed as expected and decreased the number of premature ventricular contractions, or PVCs in patients who survived a heart attack. However, these drugs also resulted in more deaths than standard care.

It was so bad researchers ended the trial early. These are effective anti-arrhythmic agents in other situations, but use in patients with coronary artery disease is undertaken with extreme caution, if at all.

What does this mean for the healthcare consumer? It means you should question the treatments you are being offered.

Do we know if the treatment is effective in improving meaningful endpoints? Will it improve quality of life or prevent premature death?

If not, that means we are relying on surrogate endpoints. Is there another treatment that shows benefits for those meaningful endpoints? If so, why not go with the established treatment instead?

Another benefit is in health claims of treatments that don’t have to be prescribed by physicians. Foods, supplements, diet plans, and other products often make health claims (even when they aren’t supposed to). Understanding the claims they make in light of the outcomes you are looking for gives you a tool to evaluate them.

Surrogate endpoints are useful. In the absence of other treatment options they can offer some hope. They also point researchers in the direction further research needs to take. But as patients, we need to understand that a great surrogate outcome doesn’t necessarily lead to a happy ending.

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