Simple measures of kidney function and damage may be just as good at predicting who is at risk for heart failure and death from heart attack and stroke as traditional tests of cholesterol levels and blood pressure, new Johns Hopkins Bloomberg School of Public Health-led research suggests.
Publishing in the Lancet Diabetes and Endocrinology on May 29, the researchers say their data may help physicians make better decisions about whether patients need lifestyle modifications such as better diets and more exercise or treatments such as statins, medication widely used for cardiovascular disease prevention.
Most importantly, the researchers note, the information is already widely available for many patients. The most common assessment of kidney function checks the blood for creatinine, a waste product of the muscles, and reflects how well the kidneys are filtering it out (called an estimated glomerular filtration rate, or eGFR). The test is given an estimated 290 million times every year in the United States. Another key test measures albuminuria, or how much of the protein albumin leaks out of the kidney and into the urine. Higher amounts indicate the presence of kidney damage. It is also a fairly common test, particularly in patients with diabetes, hypertension and kidney disease.
“If health care providers have data on kidney damage and kidney function - which they often do - they should be using those data to better understand a patient’s risk of cardiovascular disease,” says study lead author Kunihiro Matsushita, MD, PhD, an assistant scientist in the Bloomberg School’s Department of Epidemiology. “Cholesterol levels and blood pressure tests are good indicators of cardiovascular risk, but they are not perfect. This study tells us we could do even better with information that often times we are already collecting.”
The Chronic Kidney Disease Prognosis Consortium coordinated by Professor Josef Coresh, MD, PhD, and colleagues at the Johns Hopkins Bloomberg School of Public Health analyzed data from 24 studies that included more than 637,000 participants with no history of cardiovascular disease and the results of tests of eGFR and albuminuria. They found that both eGFR levels and albuminuria independently improved prediction of cardiovascular disease in general and particularly heart failure and death from heart attack and stroke, but albuminuria was the stronger predictor. It outperformed cholesterol levels and systolic blood pressure - and even whether someone is a smoker - as a risk factor for heart failure and death from heart attack or stroke.
Several clinical guidelines already recommend that patients with diabetes, hypertension and the possibility of chronic kidney disease be evaluated for kidney function and kidney damage.
Matsushita says the new data demonstrate that other individuals not covered by the recommendations may also benefit from having their kidneys assessed. For example, he says, the ability to predict cardiovascular risk was particularly robust in black study participants when eGFR and albuminuria were considered.
Cardiovascular risk factors
There are many risk factors associated with coronary heart disease and stroke. Some risk factors such as family history, ethnicity and age, cannot be changed. Other risk factors that can be treated or changed include tobacco exposure, high blood pressure (hypertension), High cholesterol, obesity, physical inactivity, diabetes, unhealthy diets, and harmful use of alcohol.
Of particular significance in developing countries is the fact that while they are grappling with increasing rates of cardiovascular disease, they still face the scourges of poor nutrition and infectious disease. Nevertheless, with the exception of sub-Saharan Africa, cardiovascular disease is the leading cause of death in the developing world.
You will not necessarily develop cardiovascular disease if you have a risk factor. But the more risk factors you have the greater is the likelihood that you will, unless you take action to modify your risk factors and work to prevent them compromising your heart health.
The biological mechanisms linking kidney disease to cardiovascular disease aren’t well understood, but Matsushita says that poorly functioning kidneys can lead to a fluid overload that may result in heart failure. He says that people with kidney disease tend to not receive certain medications that can reduce heart ailments, such as statins, likely because patients with kidney disease frequently are excluded from clinical trials performed to prove the efficacy of these medicines.
“Estimated Glomerular Filtration Rate and Albuminuria for Prediction of Cardiovascular Outcomes: A Collaborative Meta-Analysis” was written by Kunihiro Matsushita, Josef Coresh, Yingying Sang, John Chalmers, Caroline Fox, Tazeen Jafar, Simerjot K. Jassal, Gijs W. D. Landman, Paul Roderick, Toshimi Sairenchi, Ben Schöttker, Anoop Shankar, Michael Shlipak, Marcello Tonelli, Jonathan Townend, Arjan van Zuilen, Kazumasa Yamagishi, Kentaro Yamashita, Ron Gansevoort, Mark Sarnak, David G. Warnock, Mark Woodward, and Johan Arnlov, for the CKD Prognosis Consortium.
This research was supported by the US National Kidney Foundation and the National Institutes of Health’s National Institute of Diabetes and Digestive and Kidney Diseases (R01DK100446-01).
Modifiable risk factors
Hypertension is the single biggest risk factor for stroke. It also plays a significant role in heart attacks. It can be prevented and successfully treated but only if you have it diagnosed and stick to your recommended management plan.
Abnormal blood lipid levels, that is high total cholesterol, high levels of triglycerides, high levels of low-density lipoprotein or low levels of high-density lipoprotein (HDL) cholesterol all increase the risk of heart disease and stroke. Changing to a healthy diet, exercise and medication can modify your blood lipid profile.
Tobacco use, whether it is smoking or chewing tobacco, increases risks of cardiovascular disease. The risk is especially high if you started smoking when young, smoke heavily or are a woman. Passive smoking is also a risk factor for cardiovascular disease. Stopping tobacco use can reduce your risk of cardiovascular disease significantly, no matter how long you have smoked.
Physical inactivity increases the risk of heart disease and stroke by 50%. Obesity is a major risk for cardiovascular disease and predisposes you to diabetes. Diabetes is a risk factor for cardiovascular disease.
Type2 diabetes a major risk factor for coronary heart disease and stroke. Having diabetes makes you twice as likely as someone who does not to develop cardiovascular disease. If you do not control diabetes then you are more likely to develop cardiovascular disease at an earlier age than other people and it will be more devastating. If you are a pre-menopausal woman, your diabetes cancels out the protective effect of estrogen and your risk of heart disease rises significantly.
A diet high in saturated fat increases the risk of heart disease and stroke. It is estimated to cause about 31% of coronary heart disease and 11% of stroke worldwide.
Being poor, no matter where in the globe, increases your risk of heart disease and stroke. A chronically stressful life, social isolation, anxiety and depression increase the risk of heart disease and stroke.
Having one to two alcohol drinks a day may lead to a 30% reduction in heart disease, but above this level alcohol consumption will damage the heart muscle.
Certain medicines may increase the risk of heart disease such as the contraceptive pill and hormone replacement therapy (HRT).
Left ventricular hypertrophy (LVH) is a risk factor for cardiovascular mortalit