South London stroke rates drop by 40% since 1995, statins credited

A new study has found that the incidence of strokes in a large area of South London has declined by more than a third during the 15 years between 1995 and 2010.

Researchers from King’s College in London say that the number of people suffering from strokes has fell by 39.5% in that time period in the area. Incidence of strokes was calculated at 247 per 100,000 people in 1995, however it was only 149.5 per 100,000 in 2010.

Approximately 152,000 people each year in the United Kingdom suffer from a stroke. There are two main types of stroke – ischaemic and haemorrhagic. The former accounts for a staggering 80% of all cases of stroke. An ischaemic stroke occurs when blood flow to the brain is prevented by either a blood clot or clump of fat. There is a high risk of a blood clot if your arteries have narrowed and clogged with fatty deposits; known as atherosclerosis. Major risk factors for atherosclerosis include smoking, high blood pressure, high cholesterol, obesity, diabetes and a family history of heart disease or stroke.

A haemorrhagic type of stroke is brought on due a weakened blood vessel supplying the brain rupturing and resulting in bleeding into the surrounding brain and brain damage. Two types of weakened blood vessels will typically cause a haemorrhagic stroke: aneurysms and arteriovenous malformations (AVMs).

The researchers involved in the new study say the decline may be attributed to more people adopting a healthier lifestyle and the positive effects of cholesterol-lowering medications (statins), such as Lipitor (Atorvastatin) and Crestor (Rosuvastatin). Both drugs work to lower LDL, or “bad” cholesterol, and raise patients’ good HDL levels. It is estimated that statins are currently prescribed to an incredible 7 million in the United Kingdom – around a tenth of the population.

The team from King’s College looked at data extracted from the South London Stroke register, a database that covers an area with over 350,000 people in.

They found that rates of stroke incidence generally had fallen in men, women, white patients and those over the age of 45. However, similar declines in rates were not evident in those aged 15 to 44, or black patients, according to the researchers.

“We observed a higher prevalence of hypertension and diabetes mellitus in black patients compared with white patients in each of the four time periods in all age groups,” they commented.

“Other possible explanations for ethnic disparities include cultural differences in perceptions of health and the health care system, environmental exposures, genetic factors, socioeconomic status, and educational attainment.”

Professsor Graham MacGregor, chairman of charity Blood Pressure UK, said advances in medical knowledge had resulted in much more effective treatments being available for patients.

“We’ve got better blood pressure drugs and they are used more effectively. In the past GPs would prescribe one drug. We now know they work more effectively in combination, and they are often more acceptable to patients, with fewer side effects, so they take them and don’t leave them in the medicines cupboard. Statins cut the risk of stroke by 30 to 40 per cent so they have also played a part, but we need to do more.”

Dr Madina Kara, researcher at the Stroke Association, was clearly delighted with the findings from the study. She said: “It’s encouraging to see such a striking reduction in the number of people having a stroke in the past 16 years. Public health campaigns around the risk factors for stroke, such as high blood pressure and smoking are helping people to take control of their health and reduce their risk of stroke. This reduction, however, is not being mirrored in those under 45 years old, and the black population, where the incidence of stroke remains high.”

She also explained why certain sectors of the population could be more at risk compared to others. “We know that the African-Caribbean community are at greater risk of sickle cell disease, diabetes and high blood pressure – conditions that can lead to stroke. This means they are twice as likely to have a stroke compared to the white population. In addition, haemorrhagic stroke, caused by bleeding within or around the brain, is more common in younger adults,” she said.

Dr Kara added: “Stroke changes lives in an instant and can have a devastating physical and emotional impact on not only the stroke survivor, but their family and carers as well. To help reduce stroke across the whole population, we all need to take steps to reduce our risk.”