David Brill
The complexity of cardiology guidelines is growing but new recommendations are often unsupported by scientific evidence, a recent study has found.
The analysis of American College of Cardiology (ACC) / American Heart Association (AHA) clinical practice guidelines shows that the number of recommendations has risen considerably in the past 24 years.
The balance of recommendations, however, has shifted towards ‘class II’ – those that reflect a conflict of evidence or a divergence of opinion. The proportion of class I recommendations has remained largely unchanged.
Just 11 percent of all recommendations in the most recent guidelines are based on evidence level A. Almost half are based on level C – the lowest level – comprising expert opinion, case studies or standards of care.
The study, published in the Journal of the American Medical Association, was accompanied by an editorial calling for guidelines to be abolished unless the present system can be overhauled. [2009;301(8):831-41; 2009;301(8):868-9]
“Unfortunately, too many current guidelines have become marketing and opinion-based pieces, delivering directive rather than assistive statements,” wrote Drs. Terrence Shaneyfelt and Robert Centor from the University of Alabama, US.
“If all that can be produced are biased, minimally applicable consensus statements, perhaps guidelines should be avoided completely. Unless there is evidence of appropriate changes in the guideline process, clinicians and policy makers must reject calls for adherence to guidelines.”
Dr. Pierluigi Tricoci, lead author of the study, was more cautious in his response – acknowledging room for improvement with the format of guidelines but saying that they remain “important and useful” documents.
“The main message of our paper is that in cardiology, which we believe is one of the most advanced and evidence-based fields in medicine, we have a huge gap in knowledge,” said Tricoci, a cardiologist at Duke University, US. “In most situations that we find in clinical practice we don’t have enough supporting evidence that helps us make clinical decisions on what’s best for the patient.
“We hope that [this study] gives out the right message because we are not in a very good situation right now. Institutions and the government have to understand that there is a lot of research that is not well funded … we want to improve our current situation to close those gaps.”
Tricoci and colleagues reviewed 53 separate guidelines covering 22 topics. Excluding those which were never revised or updated, the number of recommendations has risen by 48 percent from the first to the latest editions of each document. The total number of recommendations rose from 1,330 in 1984 to 1,973 in 2008.
The levels of evidence vary widely between diseases. More than 20 percent of recommendations in heart failure and ST-segment elevation myocardial infarction guidelines, for example, have evidence level A. For valvular heart disease guidelines, however, just one of 320 recommendations is based on level A.
The ACC and the AHA welcomed the study’s findings in a joint statement, calling it a “valuable and important message” about the need to invest more in research.
“There are gaps in the evidence base for patient care, gaps that could be eliminated if more clinical research were funded, especially comparative effectiveness research that specifically compares one kind of diagnostic procedure or treatment with another,” said ACC president Dr. Douglas Weaver.
“Improving our evidence base can lead to even greater improvements in treatment and in saving lives.”
The balance of recommendations, however, has shifted towards ‘class II’ – those that reflect a conflict of evidence or a divergence of opinion. The proportion of class I recommendations has remained largely unchanged.
Just 11 percent of all recommendations in the most recent guidelines are based on evidence level A. Almost half are based on level C – the lowest level – comprising expert opinion, case studies or standards of care.
The study, published in the Journal of the American Medical Association, was accompanied by an editorial calling for guidelines to be abolished unless the present system can be overhauled. [2009;301(8):831-41; 2009;301(8):868-9]
“Unfortunately, too many current guidelines have become marketing and opinion-based pieces, delivering directive rather than assistive statements,” wrote Drs. Terrence Shaneyfelt and Robert Centor from the University of Alabama, US.
“If all that can be produced are biased, minimally applicable consensus statements, perhaps guidelines should be avoided completely. Unless there is evidence of appropriate changes in the guideline process, clinicians and policy makers must reject calls for adherence to guidelines.”
Dr. Pierluigi Tricoci, lead author of the study, was more cautious in his response – acknowledging room for improvement with the format of guidelines but saying that they remain “important and useful” documents.
“The main message of our paper is that in cardiology, which we believe is one of the most advanced and evidence-based fields in medicine, we have a huge gap in knowledge,” said Tricoci, a cardiologist at Duke University, US. “In most situations that we find in clinical practice we don’t have enough supporting evidence that helps us make clinical decisions on what’s best for the patient.
“We hope that [this study] gives out the right message because we are not in a very good situation right now. Institutions and the government have to understand that there is a lot of research that is not well funded … we want to improve our current situation to close those gaps.”
Tricoci and colleagues reviewed 53 separate guidelines covering 22 topics. Excluding those which were never revised or updated, the number of recommendations has risen by 48 percent from the first to the latest editions of each document. The total number of recommendations rose from 1,330 in 1984 to 1,973 in 2008.
The levels of evidence vary widely between diseases. More than 20 percent of recommendations in heart failure and ST-segment elevation myocardial infarction guidelines, for example, have evidence level A. For valvular heart disease guidelines, however, just one of 320 recommendations is based on level A.
The ACC and the AHA welcomed the study’s findings in a joint statement, calling it a “valuable and important message” about the need to invest more in research.
“There are gaps in the evidence base for patient care, gaps that could be eliminated if more clinical research were funded, especially comparative effectiveness research that specifically compares one kind of diagnostic procedure or treatment with another,” said ACC president Dr. Douglas Weaver.
“Improving our evidence base can lead to even greater improvements in treatment and in saving lives.”
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