Linköping University Medical Dissertations No 547
Possible causes for the differences in
coronary heart disease mortality between Lithuania and Sweden
The LiVicordia Study
Akademisk avhandling som för avläggande av medicine doktorsexamen kommer att offentligt försvaras i Berzeliussalen, Hälsouniversitetet, Linköping, onsdagen den 18 mars 1998, kl 09.00. Fakultetsopponent är Professor Michael Marmot, Department Epidemiology and Public Health, University College and Middlesex School of Medicine, London, and London School of Hygiene and Tropical Medicine.
Background: In recent decades coronary heart disease (CHD) mortality has declined in Western Europe and increased in Central and Eastern Europe. A large difference in CHD mortality has developed and the causes are not known. Lithuania and Sweden had similar CHD mortality rates for middle-aged men twenty years ago but in 1994 this mortality was four times higher in Lithuania than in Sweden. Also within countries CHD mortality is higher in low socioeconomic groups.
Aim of the study: The LiVicordia (Linköping-Vilnius-coronary-artery-disease-risk-assessment) study aimed at identifying possible explanations for the different CHD mortality rates in the two countries.
Method: This cross-sectional study concomitantly compared 150 randomly sampled 50-year-old men in each of the cities Vilnius, Lithuania and Linköping, Sweden from October 1993 until March 1995 using identical, standardised methodology. Investigations included a broad range of traditional and psychosocial risk factors for CHD, measures of oxidative stress, a standardised laboratory stress test and ultrasound measures of peripheral atherosclerosis.
Results: The differences found in traditional risk factors for CHD were small. Systolic blood pressure (SBP) was higher in Vilnius men, smoking was similar and plasma LDL cholesterol levels higher in Linköping men. Lower serum levels of the lipid soluble antioxidant vitamins b-carotene, lycopene and g - tocopherol were found in Vilnius men, and also a higher susceptibility of LDL to oxidation in vitro. An unfavourable pattern of psychosocial risk factors for CHD: job strain, social isolation, depression and vital exhaustion characterised Vilnius men, who also showed an attenuated cortisol response to the laboratory stress test. This stress response has earlier been shown in states of chronic stress; loss of dynamic capacity to respond to new demands may be a predisposing factor for disease. Vilnius men had more peripheral atherosclerosis; thicker intima media, more and larger plaques and greater stiffness. Measures of atherosclerosis related to SBP, smoking, LDL cholesterol and b-carotene. The same unfavourable profile of risk factors for CHD, which characterised Vilnius men, was also found in underprivileged groups within the cities. There were few differences in traditional risk factors.
Conclusions: Thus, based on our survey on risk factors for CHD, it can be stated that traditional risk factors seem not to explain the different CHD mortality rates between Lithuania and Sweden. Possible alternative explanations are psychosocial strain and oxidative stress. These factors were also found among men in underprivileged groups within the cities. Therefore the influence of the risk factors studied may be relevant also for socioeconoic inequalities in CHD mortality within countries.
Department of Health and Environment,
Division of Social and Preventive Medicine and Public Health Science
Faculty of Health Sciences, Linköpings Universitet, S-581 85 Linköping