October 6th, 2014
Nissen Urges Prompt Revision of Cardiovascular Guidelines
Larry Husten, PHD
Sparked by a new study that once again finds serious flaws in the cardiovascular risk calculator at the heart of the American College of Cardiology/American Heart Association cardiovascular guidelines, Steve Nissen states that “the ACC and AHA should promptly revise the guidelines to address the criticisms offered by independent authorities.” The CV risk calculator is a key component of the guidelines, since people are generally considered candidates for statins if they have a 10-year estimated risk of CV disease of 7.5% or higher according to the equations used by the calculator.
In a study published in JAMA Internal Medicine, Nancy Cook and Paul Ridker, analyzing data from the Women’s Health Study, offer fresh evidence that the cardiovascular risk calculator used in the ACC/AHA cholesterol guideline is flawed. They found that the predicted rate of cardiovascular disease using the guideline calculator was significantly higher than the actual observed rate in the trial. They considered and ruled out several “alternative explanations” for the discrepancy, including underascertainment of events and the increased use of statins and revascularization procedures in their population.
Noting that there have been at least seven studies now finding similar flaws in the CV risk calculator, they write that “recalibration of the pooled data sets might provide a solution to this problem.”
In his invited commentary, Nissen writes that “guidelines are effective only when they involve the participation and consent of the stakeholders whose behavior they intend to govern.” Because they were developed without “transparency and public involvement,” he writes, they “represent an important failure of guideline governance and oversight process. Rather than forging a consensus on cholesterol management, the guidelines have further polarized the debate on appropriate use of statin medications.”
Nissen calculates that overestimation of CV risk would lead to millions of additional U.S. patients receiving statins. “While statins are valuable drugs, particularly in secondary prevention, they do have downsides, and prudence requires not administering drugs to patients who will likely not benefit.”
In the future, Nissen proposes, risk calculators should be published and subject to external validation before being adopted. More generally, the guideline process “should be more open and transparent and include a public comment period.”
Elliott Antman, president of the American Heart Association, had the following response to the new publications:
“These comments are the same that we heard and addressed when we published the guidelines last year. Multiple publications since that time have validated the concepts and the utility of the risk assessment tool and cholesterol guidelines. In addition, we continue to receive positive feedback from healthcare providers who use the guidelines as a tool to drive discussions with their patients about appropriate care.”
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The concerns raised by Cook and Ridker deserve further review, debate, discussion and testing, as appropriately noted by Nissen. Surely the lack of open process as used for ATP-I, II and III, is a significant drawback of the 2013 ACC/AHA guidelines, independent of their content.
In addition, three more key problems regarding the ACC/AHA guidelines remain insufficiently considered and discussed by the medical community:
1. The cutoff of 7.5% 10 year risk not only appears to be arbitrary (as noted by Nissen) but is also quite low. The new risk estimator includes stroke and so a 7.5% risk is closer to a 5% risk with the traditional Framingham risk estimator. There was much controversy over suggestions for use of statins in patients with “intermediate risk” by Framingham even at a threshold of 10%, and much more controversy at 5%.
2. The 2013 ACC/AHA guidelines state, “Nonstatin therapies do not provide acceptable ASCVD risk reduction benefits compared to their potential for adverse effects in the routine prevention of ASCVD.” There is considerable evidence for ASCVD risk reduction for non-statins in monotherapy, and there is also some strongly suggestive evidence for favorable risk/benefit for these same agents as statin adjuncts. The fact that this evidence was excluded by the ACC/AHA guideline writers was unprecedented and is unfortunate in that it has led to condemnation of a common and reasonable part of clinical practice.
3. Goals for LDL-C and Non-HDL-C lowering have always been the centerpiece for lipid guidelines in the US and worldwide. Deletion of these goals in the 2013 ACC/AHA guidelines has been met by strong disapproval by European and Canadian expert panels, as well as by US-based professional societies.
Goals for LDL may have been a centerpiece – but they were not based on a strategy trial – what has been done are trials of fixed doses of specific meds – and in some cases the meds lowered risk – and in others they did not. Targets cannot be considered Class IA evidence – that is what the panel concluded. With regard to the Nissen editorial – I am not clear why he thinks that these guidelines had less transparency than any other AHA/ACC guideline – the process of approval was the same – and the writing committee, like any ACC/AHA committee, did their work out of public view until it was time to circulate to the organizations.