Tuesday, October 17, 2006
Until 2004, an LDL cholesterol level of less than 130 milligrams a deciliter was considered low enough. But the updated guidelines recommend that high-risk patients reduce their level even more — to less than 100 — while patients at very high risk are given “the option” of reducing LDL cholesterol to less than 70. Patients often have to take more than one cholesterol-lowering drug to achieve those targets.
Except that it has quickly gone from being an "option" to being a mandate, at least among cardiologists. I routinely get scolding letters from cardiologists for not adding more drugs to my patients already complicated regimens to achieve LDL levels of less than 70. I have to agree with the authors of the review:
“This paper is not arguing that there is strong evidence against the LDL targets, but rather that there’s no evidence for them,” said Dr. Rodney A. Hayward, a study author, adding that this was largely because of the way clinical trials had been devised and carried out.
“If you’re going to say, ‘Take two or three drugs to get to these levels,’ you need to know you’re doing more benefit than harm,” said Dr. Hayward, who is director of the Veterans Affairs Center for Health Services Research and Development and a professor at the University of Michigan Medical School. He said he was particularly concerned because there was little long-term safety data about the drug combinations used to lower cholesterol.
The review is really a critique of the evidence used by the National Cholesterol Education Program Adult Treatment Panel III when they issued their guidelines. The crux of the argument in favor of chasing LDL levels to less than 70 amounts to this:
Recent clinical trials nonetheless have documented ... that for every 1% reduction in LDL-C [low-density lipoprotein cholesterol] levels, relative risk for major CHD [coronary heart disease] events is reduced by approximately 1%. HPS [Heart Protection Study] data suggest that this relationship holds for LDL-C levels even below 100 mg/dL [2.59 mmol/L].
The authors of the review then proceed to demolish every "recent clinical trial" cited by the NCEP. In addition, they fail to find any other trials that support the conclusion. Instead, they find diminishing with ever lower levels, "just as when a piece of paper is serially torn in half and half is thrown away, the halves that are thrown away get smaller and smaller."
They also point out that the studies compare patients who reached LDL levels of <70 to all those who did not reach that level. The problem is that the "all those who did not" is a very wide and ranging category - from people who are just a few units away from the goal (and thus at smaller risk) to those who are a hundred units away (and at higher risk of having heart disease):
In medicine, modest deviations from "ideal" levels (for example, a hemoglobin A1c level of 7.5% vs. a goal of <7% or a sodium level of 132 mmol/L vs. a goal of 135 to 145 mmol/L) often result in trivial risk. Marked deviations from treatment targets, however, are often associated with dramatic and often logarithmic increases in risk. In fact, a recent report from the Framingham Heart Study suggested that this is true for a variety of cardiovascular risk factors, including cholesterol levels. If the only comparison made is between those who reach the strict goal and all others, we can mistakenly think that not achieving the treatment goal results in moderate risk when almost all of the risk is caused by more substantial deviations from the goal.
And finally, thankfully, they address the downsides of treatment. Every treatment has its risks and cholesterol lowering drugs are no different:
The articles we reviewed often advocated for tight LDL cholesterol goals without discussing possible risks, patient burden, and societal costs associated with the treatments needed to reach those goals. This is particularly important because achieving moderate clinical control is often easy whereas achieving the ideal goal often requires substantial costs and patient burden, such as polypharmacy. Many treatments also carry at least some risk for harm. Therefore, failure to recognize this phenomenon can result in promoting unsafe treatment recommendations for those with small to moderate deviations from the proposed treatment goal.
Which is exactly what medicine has been doing for the past several years, not only in cholesterol management, but in diabetes management and hypertension management.
P.S. The review is also a very good lesson in how to interpret studies critically. It could be a template for a class in critical reading of research papers.
P.P.S. DB's MedRants points out the implications for pay for performance.
posted by Sydney on 10/17/2006 08:53:00 PM 1 comments
I recently saw a blurb about a study being undertaken to look at the physical and mental side effects of statins. It seems a surprising number of people have strong reactions to these medications, that are being ignored and written off as due to age. Given some of the dosage levels and combinations you do not have to be a doctor to understand the very real possibility of producing a negative reaction.
By 9:13 AM, at