The SEARCH Study - Introduction
SEARCH is investigating the effects of two interventions in people who have had a heart attack. The treatments are called simvastatin which is used to lower blood cholesterol levels, and folic acid with vitamin B12 which lowers homocysteine levels in the blood. Simvastatin at standard doses is well recognised to reduce the risk of heart attacks and strokes but it is not clear how intensively people should have their cholesterol levels lowered. So, in SEARCH, a more intensive simvastatin dose of 80mg daily is being compared with a more standard 20mg daily dose. At the end of the study the numbers of people experiencing a heart attack, stroke or procedure to open the arteries (called a revascularisation) will be compared between those allocated 80mg simvastatin and those allocated 20mg simvastatin.
It has also been known for many years that people with higher homocysteine levels in the blood have a higher risk of strokes and heart attacks. Since the B vitamins, folic acid and vitamin B12 lower homocysteine levels in the blood, it is hoped that this might protect against strokes and heart attacks. So, half the volunteers are taking active folic acid and vitamin B12 and half are taking a dummy version. The outcomes in the two groups will be compared.
People who have had a heart attack were identified from hospital and other records, and were invited by local investigators to a clinic appointment with a research nurse in one of 100 or so specially set-up clinics across the UK (as shown on the map). Medical histories and measurements were taken and the study was explained to them and a Patient Information Leaflet provided. Just over 12,000 people agreed to take part in the study.
Those who agreed to take part were "randomized". This means that they were randomly allocated to take either 20mg or 80mg simvastatin each day, and were also randomly allocated to take either folic acid 2mg plus vitamin B12 1mg daily or a matching dummy tablet (called a placebo) each day. The specially made packs of pills were given to them at their clinic appointment.
After being randomised into the study, the study volunteers were invited to come back to the clinics at 4, 8 and 12 months and then every six months until the end of the study. Nurses took details of any medical problems they may have had and provided new packs of tablets when required. Blood samples were also taken to make sure the treatments were having no unwelcome effects. If people were unable to attend the clinic then the nurses conducted the interview by telephone but such people were no longer taking study simvastatin tablets.
The main study results can be found on our results page.
During the study we occasionally sent newsletters to the study volunteers; we provide them here for interest: