Trends in prevalence of ultrasound-assessed carotid atherosclerosis in a general population over time. The Tromsø Study 1994-2016

Background: During the past decades, there has been a shift in risk factor levels in many high-income countries, with decrease in smoking, blood pressure and cholesterol levels, while body mass index, obesity and diabetes increase. The diverging trends may have opposite effects on prevalence of atherosclerosis. We aimed to assess carotid plaque prevalence and the association with risk factor levels in a general population over a period of 22 years. Methods: Prevalence of plaque, number of plaques and total plaque area in the carotid arteries were assessed in three repeated cross-sectional surveys of the population-based Tromsø Study from 1994 through 2016. The number of participants from the first to the last survey was 6362, 7069 and 3021. All surveys included physical examinations, questionnaires, and blood samples. Multivariable logistic regression analysis models were fitted to assess the relationship between risk factors and carotid plaque. Results: We found no significant change in plaque burden over a period of 22 years, neither when measured as plaque presence, plaque number or total plaque area. Plaques were more frequent in men (70%) than in women (59.4%) and increased by age. Systolic blood pressure and smoking increased, while BMI and diabetes decreased over time both in participants with and without plaque. Most risk factors remained higher in participants with plaque than in plaque- free participants while cholesterol levels decreased and reached similar levels in both groups. Age, male sex, systolic blood pressure, smoking, diabetes and HDL cholesterol (inverse) were associated with plaque prevalence. Conclusions: Plaque prevalence remained stable in the observation period. Favorable reductions in systolic blood pressure, cholesterol and smoking may have been partly counteracted by increased diabetes prevalence. Risk factor levels remained higher in participants with plaque than in plaque-free participants, indicating a potential for further improvement in primary prevention of carotid atherosclerosis