Experts say the formula used to calculate risk of heart diseases in people uses very old data and overestimates risk of heart ailments
New guidelines for management of cholesterol, released by two private organizations in the US on November 13, are being criticized for promoting use of drugs even in people who don’t require them. The guidelines which have come after a long wait allegedly encourage use of drugs like statin among patients of diabetes and those facing heart risks. Apart from disagreement with certain clauses in the new criteria, a comment published in The Lancet, a journal of medicine, has questioned the risk-assessment calculator released along with the guidelines.
The American Heart Association and American College of Cardiology have released the new guidelines to reduce cholesterol among patients with certain level of risk of heart diseases. The new suggestions which focus on reducing rate of heart stroke rather than just lowering cholesterol levels in the body have been appreciated. But the means proposed to prevent heart risks have drawn flak from both doctors and experts.
The calculator that has been prepared for risk assessment and is being promoted along with the guidelines, has been criticized for overestimating the risk of heart ailments by 75-150 per cent. A comment by Paul M Ridker and Nancy R Cook of Center for Cardiovascular Disease Prevention, Divisions of Preventive Medicine and Cardiology, Brigham and Women’s Hospital, Boston, has been published in The Lancet based on their study conducted over the past few days. The authors have pointed out that last year when they were sent a draft by the National Institute of Health’s National Heart, Lung, and Blood Institute on similar guidelines to be reviewed, they had concluded that the lifestyle and habits of the population that was observed while conducting the study was a lot different from those who would be adopting them as they have been observing these people for nearly ten years now.
A year on, the same problems persist. Researchers and doctors claim that again the data from the 1990s has been used as reference to determine how various risk factors like cholesterol levels and blood pressure led to actual heart attacks and strokes.
Implications on India
In the absence of guidelines for cholesterol control in most developing nations including India, doctors, mostly private practitioners, refer to guidelines from the US and other developed nations.
"The major problem is that the studies used for calculator are not reliable. Even though the ambit of research has increased, the methodological problems are crucial and need to be addressed. The flawed risk-assessment can be problematic as we will be forced to give statin to many people who do not need them at all," said Anil Dhall, director, cardiology, Delhi Heart and Lung Institute.
"Every patient's needs are different. Doctors have to see who can be put on medicines and who cannot be. The guidelines leave less scope for treating a person according to his needs," added Dhall.
Doctors can’t take decisions independently
Researchers Ridker and Cook had found that if the new guidelines and calculator are adopted, a person with low LDL (bad cholesterol) will be put on statin therapy. Meanwhile, a person who the medical fraternity believes should be given medicines, will be left out if his cholesterol levels don’t fall in the ambit of the new norms which say that patients with an LDL of 190 mg/dL or higher will be prescribed statin therapy.
"These new criteria could result in more than 45 million middle-aged Americans, who do not have cardiovascular disease, being recommended for consideration of statin therapy. This is about one in every three American adults," says another comment published in The Lancet.
Statin therapy has its own side effects. It includes muscle ache, fatigue and slight rise in blood sugar. In rare instances, it can lead to haemorrhagic stroke and a toxic breakdown of muscle tissues. Cataracts and sexual dysfunction are also common in women. About 18 per cent of people on statin suffer from these side effects.
'Guidelines are mechanical in nature'
A Lancet comment also said that instead of focusing on behavioural change, guidelines put emphasis on medical regimen.
"Other than age, the major drivers of high global risk are smoking and hypertension, for which the interventions of choice should be to eliminate cigarette use and to lower blood pressure, rather than to write a prescription for statin therapy. This is well acknowledged in the new guidelines which also addresses lifestyle factors. However, it can create confusion for doctors and physicians who will have to consider all elements (not only cholesterol levels) which can create heart risks," reads the comment.
| Comparison of old and new guidelines
People who had LDL (bad cholesterol) equal to or above 160 should be given statin
Focussed only on LDL reduction
What the new guidelines state:
The American Heart Association and American College of Cardiology named four groups of patients who should be put on statins:
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