REFINE Reykjavik Study.

About the study

One of the main purposes of the study is to increase the predictability of risk factors for the development of coronary artery disease on an individual basis. This is done by systematically adding new measurements and looking at risk factor interaction. As with conventional risk factors any new additional measurements need to be simple in order to use them for screening.
The cohort is a random sample of inhabitants of the greater Reykjavik area, from Hafnarfjördur to north of Kjalarnes, aged between 20 and 69 years.

In 2006 110 people on average were examined each month excluding the summer vacation month of July. The study had a 70% recruitment rate, resulting in the examination of 1,213 individuals. In REFINE Reykjavik Study conventional cardiovascular risk factors were examined as has been the case for 40 years at the Icelandic Heart Association. The Icelandic Heart Association risk factor study, Risk Evaluation For INfarct Estimates  (REFINE Reykjavik Study) was initiated in December 2005 and took off at full capacity at the beginning of 2006.  One of the main purposes of the study is to increase the predictability of risk factors for the development of coronary artery disease on an individual basis. This is done by systematically adding new measurements and looking at risk factor interaction. As with conventional risk factors any new additional measurements need to be simple in order to use them for screening.
The cohort is a random sample of inhabitants of the greater Reykjavik area, from Hafnarfjördur to north of Kjalarnes, aged between 20 and 69 years.

In 2006 110 people on average were examined each month excluding the summer vacation month of July. The study had a 70% recruitment rate, resulting in the examination of 1,213 individuals. In REFINE Reykjavik Study conventional cardiovascular risk factors were examined as has been the case for 40 years at the Icelandic Heart Association. They can be divided as follows:

1. Anthroprometry; height, weight, waist circumference, bioimpedance.
2. Blood pressure
3. Electrocardiogram
4. Blood tests: blood status, total cholesterol, HDL-cholesterol, triglycerides, glucose, creatinine.
5. Questionnaire: questions are asked on general health, medication, smoking, physical exercise and social status.

In addition new measurements are carried out:

1. Blood is drawn for DNA extraction. A number of genetic polymorphisms potentially conferring risk of cardiovascular disease are known.
2. Ultrasound examination of the carotids;
   • Evidence of atherosclerosis (plaque) is looked for. If atherosclerosis is found, the extent is categorized into small, moderate and severe atherosclerosis. The assumption is made that atherosclerosis in one place reflects atherosclerosis elsewhere.
   • Evaluation of arterial wall thickness is performed (intima-media thickness, IMT). With specific reading program the thickness of the arterial wall is evaluated. The IMT increases with increased age and increased IMT has been associated with the risk of the cardiovascular disease. The carotids ultrasound examination and quality control is done in collaboration with Dr. M.L. Bots at the University of Utrecht.
3. Arterial distensibility. Two methods are used to evaluate the distensability in the arterial tree. Both methods are based on measuring pulse wave velocity. The faster the pulse wave velocity, the less the arterial distensibility reflecting atherosclerosis.
   • Firstly, blood pressure measurements are performed on the upper arm and in the groin and pulse wave measurements at the same places are connected to an electrocardiogram. These measurements are taken in collaboration with Dr. Gary F. Mitchell in Boston. The same method has been used in the Framingham study under the auspices of Dr. Mitchell.
   • Secondly, so called CAVI measurements are done. The pulse wave velocity is captured by probes on the arm and at the ankle. CAVI increases with age and increased arterial stiffness. In addition the ankle brachial index is measured which has frequently been associated with  cardiovascular risk but never measured before at the Icelandic Heart Association.
4. Personality test: two personality tests are used. The relationship between personal traits and the risk of cardiovascular disease is clearly emerging but this relationship has not frequently been examined in the general population.
   • Firstly, the NEO-FFI personality test is used. This test was standardized by Dr. Fridrik H. Jonsson, a psychologist and associate professor at the University of Iceland, who collaborates with the Icelandic Heart Association on the interpretation of the results. This test is accepted internationally and a longer version of the test (NEO-PI-R) has been used to examine personality traits for many nations.
   • Secondly, the DS-14 personality test is used. The test examines specifically a sub-group of personality that has been associated with cardiovascular disease.
5. Heart rate variability: participants are connected to a heart rate meter at the beginning of the study and the heart rate is recorded during the examination. The variability and speed of the heart rate has been associated with cardiovascular diseases. Reading and interpretation is done in collaboration with Dr. Julian F. Thayer at the Ohio State University.