Anglo-Danish-Dutch Study of Intensive Treatment In People with Screen Detected Diabetes in Primary Care (ADDITION)
The Anglo-Danish-Dutch Study of Intensive Treatment In People with Screen Detected Diabetes in Primary Care (ADDITION study) was initiated in 1999. The primary objectives of the study were:
- To evaluate whether population-based screening for undiagnosed type 2 diabetes was feasible in a primary care setting
- To assess whether subsequent optimised intensive treatment of diabetes and associated risk factors among screen-detected patients were feasible in primary care and benefitted the patients, and
- To quantify the harms associated with screening. Previous screening studies have focused on people with pre-diabetes and how to prevent progression from pre-diabetes to diabetes.
The study consists of a screening phase followed by a pragmatic trial of intensive treatment compared to routine care in four centres (Denmark, Cambridge UK, the Netherlands and Leicester UK). Each centre has subsequently followed its participants at 1, 5 and 10 years.
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More about ADDITION
Diabetes meets many of the criteria for screening. A high proportion of people have undiagnosed diabetes, many individuals present with complications when they are diagnosed, and there is a long “latent” period between when the disease starts and when a person experiences symptoms and presents at their GP. People with diabetes have an increased risk of developing cardiovascular disease (heart attack or stroke). It is logical to suggest that if we found people earlier in the disease trajectory and treated them before symptoms developed, that we could reduce the risk of them suffering from an early death or experiencing a heart attack or stroke. However, there is little evidence to support this idea, and there are a number of uncertainties concerning the potential benefits of population-based screening for type 2 diabetes
The Anglo-Danish-Dutch Study of Intensive Treatment In People with Screen Detected Diabetes in Primary Care (ADDITION study) was set-up in 2001 to answer some of these uncertainties. The study consists of a screening phase followed by a pragmatic trial of intensive treatment compared to routine care in four centres (Denmark, Cambridge UK, the Netherlands and Leicester UK).
ADDITION Treatment Trial
Following screening in 343 practices, 3,057 eligible participants with screen-detected diabetes agreed to take part in the ADDITION treatment trial. In Cambridge, confirmation of the diagnosis of diabetes and baseline assessments were carried out in our clinical research facilities in Ely, Wisbech and Addenbrooke’s with additional measurements in Peterborough and Huntingdon. As a result of the screening programme 867 people in the East Anglia region were made aware that they had diabetes.
Half of the patients diagnosed with type 2 diabetes in the ADDITION study went on to receive standard care for type 2 diabetes from their general practice following national guidelines. The other half received an intensive treatment programme to reduce their risk of cardiovascular disease.
This treatment included:
- educational materials designed to help patients to improve their diet, increase their physical activity and stop smoking.
- increased use of medication to reduce levels of cardiovascular risk factors such as blood glucose, blood pressure and cholesterol.
More information can be found here: www.addition.au.dk
We invited the two groups of patients back to our testing sites for a health assessment after one and five years. At 10 years, we collected health data from participants GP practices and national registries to assess the long term outcomes in both groups. We compared the two groups to assess whether the intensive treatment programme reduced the risk of developing cardiovascular disease and which approach patients preferred.
What have we found?
- Screening for diabetes does not make people feel anxious, depressed or falsely reassured.
- The health status of ADDITION participants was improved five years after diagnosis e.g. there were important reductions in levels of blood pressure, cholesterol and blood glucose over the five years of the study.
- Earlier diagnosis and treatment of diabetes has contributed to lower than expected rates of heart attacks and premature death, which are now similar to those in the general population without diabetes.
- Sustained reductions in glycaemia and related cardiovascular risk factors over 10 years among people with screen-detected diabetes managed in primary care are achievable and safe.
ADDITION Plus is a sub-study that involves patients within the intensive treatment programme of the ADDITION study and patients with diabetes recently diagnosed by their GP.