Kuopio Ischaemic Heart Disease Risk Factor (KIHD) Study, Nutrition

The Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) is an on-going prospective, population-based cohort study of risk factors for cardiovascular diseases, other chronic diseases and metabolic conditions in a sample of men from eastern Finland. The baseline examinations were carried out between 1984 and 1989, when 2,682 men (82.9% of those eligible) who were 42, 48, 54 or 60 years old were recruited. The first cohort consisted of 1166 men who were 54 years old, enrolled in 1984-1986, and the second cohort included 1516 men who were 42, 48, 54 or 60 years old, enrolled in 1986-1989. The baseline examinations were followed by the 4-year examinations (1991-1993), in which 1038 men from the second cohort (88% of the eligible) participated. At the 11-year examinations (1998-2001), all men from the second cohort were invited and 854 men (95% of the eligible) participated. These examinations were also the baseline for 920 postmenopausal women (78.4% of the 1173 eligible women) from the same area, aged 53-73 years. During the 20-year examination round, all men from the first and second baseline cohorts and all women were invited to the study site, and a total of 1241 men (80% of the eligible) and 634 women (81.0%) participated.

Food consumption has been assessed with an instructed food recording of four days, one of which was a weekend day, by household measures. A picture book of common foods and dishes was used to help in estimation of portion sizes. For each food item the participant could choose from 3-5 commonly used portion sizes or describe the portion size in relation to those in the book. In order to further improve accuracy, instructions were given and completed food records were checked by a nutritionist together with a participant. Nutrient intakes were estimated using the NUTRICA® 2.5 software. The databank of the software is mainly based on Finnish values of nutrient composition of foods.

Registration of the incidence of major chronic diseases and deaths during the follow up is based on the national registries (Hospital discharge registry, Cause of death register, Social Insurance Institution of Finland register for reimbursement of medicine expenses) by use of the Finnish personal identification code (social security number), and/or on findings at the re-examination rounds (such as fasting plasma glucose or 2-h oral glucose tolerance test to define type 2 diabetes in addition to data from the national registries).

The KIHD received approval from the research ethics committee of the University of Kuopio and Kuopio University Hospital, and written, informed consent was obtained from all participants. The nutrition part of the KIHD study is registered: Clinicaltrials.gov.