Guidelines for CVD treatment may be based on weaker evidence

The American College of Cardiology and the American Heart Association recommendations for cardiovascular clinical practice are based on lower levels of expert opinion or evidence, according to study findings.

Researchers examined data from ACC/AHA guidelines from 1984 to September 2008. They investigated 53 guidelines on 22 topics and 7,196 recommendations.

The number of recommendations grew from 1,330 to 1,973 for guidelines with at least one revision since September 2008. Class II recommendations demonstrated the greatest increase, according to the researchers.

Sixteen current guidelines reported levels of evidence. For 2,711 recommendations, the median for guidelines classified as level of evidence A was 11%, whereas the median for guidelines classified as level of evidence C was 48% of 1,246. Level of evidence A recommendations were mostly in class I; however, there was only a median of 19% (245/1,305) of class I recommendations that had level of evidence A, according to the study.

The researchers reported that the number of recommendations without conclusive evidence is growing.

“To remedy this problem, the medical research community needs to streamline clinical trials, focus on areas of deficient evidence and expand funding for clinical research,” they wrote. “In addition, the process of developing guidelines needs to be improved with information about the impact that recommendations based on lower levels of evidence has on clinical practice. Finally, clinicians need to exercise caution when considering recommendations not supported by solid evidence.”

JAMA. 2009;301:831-841.