Secular and longitudinal trends in cardiovascular risk in a general population using a national risk model: The Tromso Study

Background Primary prevention guidelines promote the use of risk assessment tools to estimate total cardiovascular risk. We aimed to study trends in cardiovascular risk and contribution of single risk factors, using the newly developed NORRISK 2 risk score, which estimates 10-year risk of fatal and non-fatal cardiovascular events. Design Prospective population-based study. Methods We included women and men aged 45-74 years attending the sixth and seventh survey of the Tromso Study (Tromso 6, 2007-2008, n = 7284 and Tromso 7, 2015-2016, n = 14,858) to study secular trends in NORRISK 2 score. To study longitudinal trends, we followed participants born 1941-1962 attending both surveys (n = 4534). We calculated NORRISK 2 score and used linear regression models to study the relative contribution (%R-2) of each single risk factor to the total score. Results Mean NORRISK 2 score decreased and distribution in risk categories moved from higher to lower risk in both sexes and all age-groups between the first and second surveys (p < 0.001). In birth cohorts, when age was set to baseline in NORRISK 2 calculations, risk score decreased during follow-up. Main contributors to NORRISK 2 were systolic blood pressure, smoking and total cholesterol, with some sex, age and birth cohort differences. Conclusion We found significant favourable secular and longitudinal trends in total cardiovascular risk and single risk factors during the last decade. Change in systolic blood pressure, smoking and cholesterol were the main contributors to risk score change; however, the impact of single risk factors on the total score differed by sex, age and birth cohort.