By Lynda Szczech, MD, Immediate past president of the National Kidney Foundation
A headline such as “Your medicines can cause harm to your kidneys” gets your attention, right? But the headline of “the decision to take a medicine is a balance of risk and benefit, so talk to your doctor” may not make you want to read more. In medical research, we often find ourselves with multiple studies that disagree slightly or significantly with each other on important matters such as hospitalizations and mortality, leaving statisticians to argue, the FDA to ponder, and the public to worry and question how to react. This week saw more of the same; the focus was on statins and kidney disease.
Here are some facts:
- Treating heart disease makes you live longer.
- Statins taken to lower serum cholesterol levels prolong lives.
- Statins have side effects.
This week in the British Medical Journal, a study was published describing an increased risk of acute kidney injury in people with kidney disease taking statins for their cholesterol. The group taking higher doses had an increased risk of being admitted to the hospital for acute kidney injury then the group taking lower doses of statins. The risk was also greatest in the first 120 days of therapy and declined as time on therapy continued to one and two years. The number of people with kidney disease getting admitted with kidney injury during the first 120 days of therapy was 15.1% in those receiving higher doses of statins and 12.1% in those receiving low dose statins.
Notice, first, that the baseline risk is high. Kidney injury happens a lot in people with kidney disease. That is an important fact. Why is that the case? More than likely because people with kidney disease also have heart disease and take more medications than people without kidney disease. Second, it is important to question whether this difference between 12.1 and 15.1% is caused by the higher doses of statins. This is where the arguing and pondering come in. People with more medical problems should get more interventions to lower their risk. As we look at the difference between people getting higher doses, how much of the higher risk of events is due to the fact that they could have had higher cholesterol or worse heart problems at baseline making their doctors want to give them more statin. Is their higher dose just because they had worse heart disease and not caused by the statin dose at all? And why does the risk decline as therapy is prolonged? Is the risk also related to the event (such as a heart attack or angina) that got them the prescription in the first place? Additionally, a recent trial demonstrated that high-doses of rosuvastatin reduced the likelihood or acute kidney injury related to contrast dye from radiology studies. The group receiving the high doses of statins had a 6.7% chance of acute kidney injury as compared to a 15.1% chance in the group not receiving statins.
While we juggle those points in one hand, let’s look at the benefit in the other. We learned from the SHARP study that statins prevent major cardiac events. How then do you weigh the suggestion of a risk with a proven benefit? You don’t do it alone, that’s for sure. Learn about your kidneys. Learn about your medicines. Talk to your doctors about both. The benefit of statins shouldn’t be abandoned out of fear. But the risks shouldn’t be ignored either. There are few good outfits that are “one size fits all”. Different people will require different sizes. Think of your doctor as your tailor or seamstress. Find the size that works for you. Ask questions, listen, and repeat until clear (or at least less muddy) and your kidneys will thank you.
The balance between risk and benefit is easy to weigh when there is no risk or no benefit. In these rare circumstances, the choice is clear. So to frame: