Can a simple kidney test tell if you are at risk of coronary heart disease?

This study investigated whether poor kidney function increases the risk of coronary heart disease and predicts coronary heart disease progression.

Coronary heart disease refers to a condition caused by the narrowing of blood vessels that supply the heart with blood, oxygen and nutrients. There are several risk factors that can increase the chances of developing heart disease such as age (older age increases the risk of damaged and narrowed arteries), family history, smoking (nicotine narrows blood vessels), high blood pressure, and obesity. Additionally, kidney disease (loss of kidney function) may increase the risk of heart disease and may predict the probable outcome or course of the disease (prognosis).  

Kidney function is measured using the estimated glomerular filtration rate (eGFR). The test estimates the volume of blood that is filtered by the kidneys over a given period of time. This test also measures the level of creatinine (a natural substance found in the body normally removed by the kidneys) in the blood and uses the result to calculate a number that reflects how well the kidneys are functioning. Lower eGFR results indicate increased levels of kidney disease.

This study investigated if measuring eGFR could predict heart disease prognosis in newly diagnosed coronary heart disease patients. 

This study was conducted on 31,533 coronary heart disease patients aged >30 years. Mortality was higher among patients with lower eGFR levels at the beginning of the study. The 2-year mortality rate ranged from 4.1% for those with the highest eGFR rate compared to 46% for those with the lowest eGFR rate.

The net reclassification index (NRI) was used to calculate risk of death among newly diagnosed participants. The NRI index measures if there is an improvement in prediction in clinical outcome when a new risk factor, such as eGFR, is added to a set of already known risk factors. In other words, the risk of a patient passing away within a 2-year period after diagnosis was measured based on several known risk factors such as age, gender, presence of co-existing diseases such as diabetes or hypertension, smoking, and existing treatment. The study then added eGFR to their calculation to see if it affected the prediction of death. The study found that including eGFR improved predictions by 3.2%. 

In conclusion, this study suggests that impaired kidney function increases the risk of coronary heart disease and can be used as an independent prognostic marker to help determine disease progression. 

The follow-up period of 2 years after eGFR measurements is considerably short.

If you are worried about coronary heart disease, consider discussing a glomerular filtration rate test with your doctor, and any steps you can take to reduce the risk factors associated with heart disease.