Decline in Coronary Mortality in Sweden between 1986 and 2002: Comparing Contributions from Primary and Secondary Prevention

BACKGROUND: The relative importance of risk factor reduction in healthy people (primary prevention) versus that in patients with coronary heart disease (secondary prevention) has been debated. We aimed to quantify the contribution of the two. METHODOLOGY: We used the previously validated IMPACT model to estimate contributions from primary prevention (reducing risk factors in the population, particularly smoking, cholesterol and systolic blood pressure) and from secondary prevention (reducing risk factors in coronary heart disease patients) in the Swedish population. PRINCIPAL FINDINGS: Between 1986 and 2002, about 8,690 fewer deaths were related to changes in the three major risk factors. Population cholesterol fell by 0.64 mmol/L, with approximately 5,210 fewer deaths attributable to diet changes (4,470 in healthy people740 in patients.) plus 810 to statin treatment (200 in healthy people, 610 in patients). Overall smoking prevalence decreased by 10.3%, resulting in 1,195 fewer deaths, attributable to smoking cessation (595 in healthy people, 600 in patients). Mean population systolic blood pressure fell by 2.6 mmHg, resulting in 900 fewer deaths (865 in healthy people, 35 in patients), plus 575 fewer deaths attributable to antihypertensive medication in healthy people. The majority of falls in deaths attributable to risk factors occurred in people without known heart disease: 6,705 fewer deaths compared with 1,985 fewer deaths in patients (secondary prevention), emphasizing the importance of promoting health interventions in the general population. CONCLUSIONS: The largest effects on mortality came from primary prevention, giving markedly larger mortality reductions than secondary prevention.