Heart disease and stroke risk predicted by new tools

Damage to blood vessels in eyes, kidneys and nerve cells may cause two-fold increased risk of heart attack or stroke in people with type 2 diabetes.

Individuals with diabetes are susceptible to damage to small blood vessels in the eyes, kidneys and nerve cells that can, in turn, lead to blindness, kidney failure and leg amputation. In 2004, routine screening for this damage, known as microvascular disease, was introduced in the UK.

The team, which included scientists from Imperial College London, St George’s, University of London, and St George’s University Hospitals NHS Foundation Trust, looked at data for 49,027 individuals with type 2 diabetes in the UK. They used this data to assess whether screening information on microvascular disease could also predict damage to the large blood vessels that causes heart attacks and stroke (cardiovascular disease).

The researchers found any single sign of microvascular disease resulted in around a 30% increased risk of cardiovascular disease. Risk increased with each additional factor present such that the risk was increased two fold when all three were present. Researchers found that damage to small blood vessels in the eyes, kidneys and nerve cells were at least as strong an indication of the likelihood of later cardiovascular disease as many conventionally accepted risk factors – such as high blood pressure and cholesterol.

Professor Kausik Ray, co-senior author from School of Public Health at Imperial said: “We found the presence of damage to the eyes, kidneys and nerves in combination incrementally doubled risk of cardiovascular disease, mortality and hospitalisation for heart failure. Our findings suggest that incorporating commonly available screening tests - that are already routinely assessed in those with diabetes - can significantly improve risk prediction. If applied globally, these findings have the potentially to improve therapeutic decision making in several millions of patients, simply by looking in the back of the eye, testing the feet with a microfilament and taking a dip stick test of the urine. It’s easy and cheap.”

The data, published in the journal Lancet Diabetes, suggests that continuing the screening programme for microvascular disease in GP practices is needed. Not only does this predict the risk of blindness, kidney failure and leg amputations, but it also provides a clear indication of whether an individual is likely to go on to develop cardiovascular disease.

In the UK, NICE guidelines recommend that any individual who is 10% or more likely to experience cardiovascular disease in the next 10-years should be offered a statin prescription with the aim of preventing future heart attacks and strokes. When data on microvascular disease is included in the assessment of an individual patient’s risk of cardiovascular disease, an extra 135,000 people in the UK could be offered a statin prescription appropriately as their risk would cross this predicted threshold. Furthermore, 200,000 individuals would fall below the threshold for statin treatment and consequently these lower risk groups would not be offered a statin.

The team argues this may mean earlier treatment for patients at higher risk of developing cardiovascular disease - in particular younger patients and women, who often are believed to be at low risk on the basis of age and gender. There are also potential cost benefits to the health service, by preventing more cardiovascular disease in higher risk patients. In addition to this, there would be fewer statin prescriptions – and so potentially fewer side effects - in low risk individuals.

Co-Lead author, Jack Brownrigg, of St George’s University, added: “The study has identified a very high risk group of patients with diabetes. The number of people with diabetes in the UK is rising, driven largely by obesity. These results will help us to focus preventive treatments on those patients who are at most risk of developing cardiovascular disease and should reduce the number of people with diabetes who experience a heart disease or stroke”.