Explaining the decline in coronary heart disease mortality in the Netherlands between 1997 and 2007 using IMPACTSEC model

Abstract

Introduction: The decline in coronary heart disease (CHD) mortality in the Netherlands started in the seventies and has continued in the early twenty-first century. However, socioeconomic inequalities persist. We therefore set out to determine what proportion of the recent mortality decline (from 1997 to 2007) could be attributed to advances in medical treatment and to improvements in population-wide cardiovascular risk factors, both across and within socioeconomic groups.

Methods: We used a previously applied model, IMPACT-SEC. Nationwide information was obtained on changes between 1997 and 2007 in the use of 42 treatments in 7 non-overlapping groups of patients and in cardiovascular risk factor levels in Dutch adults, aged 25 or over. The primary outcome was the number of CHD deaths prevented or postponed.

Results: The age-standardized CHD mortality fell by 48% from 269 to 141 per 100.000. This resulted in 11,200 fewer CHD deaths in 2007 than expected. The model was able to explain 72% of the mortality decline. Approximately 37% (95% confidence interval: 10%-80%) of the decline was attributable to changes in acute phase and secondary prevention treatments: the largest contributions came from treating patients in the community with heart failure (11%) or chronic angina (9%) and acute phase treatment of acute myocardial infarction (6%). Approximately 36% (24%-67%) was attributable to decreases in risk factors: blood pressure (30%), total cholesterol levels (10%), smoking (5%) and physical inactivity (1%). However, 10% more deaths could have been prevented if body mass index and diabetes would not have increased. Results were similar across socioeconomic groups.

Conclusions: CHD mortality has recently halved in The Netherlands. Equally large contributions have come from the increased use of acute and secondary prevention treatments and from improvements in population risk factors (including primary prevention treatments). Increases in obesity and diabetes represent a major challenge for future prevention policies.