Explaining trends in coronary heart disease in the Netherlands

Abstract

Background: A dramatic increase in life expectancy was observed in the last decade in the Netherlands. This increase in life expectancy has been largely attributed to declines in coronary heart disease (CHD) mortality rates. The main objective of this thesis was to explain the decline in coronary heart disease (CHD) mortality in the Netherlands between 1997 and 2007 by applying the IMPACT model to Dutch data. The second objective was to provide detailed information (by age, sex and socioeconomic circumstances) on time trends in CHD mortality, incidence, short-term case-fatality rates, risk factors, and uptake of cardiovascular treatments.

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

Results: The age-standardized CHD mortality fell 48% (from 269 to 141 per 100.000). This resulted in 11,200 fewer CHD deaths in 2007 than expected. About 37% (95% confidence interval: 10%-80%) of these deaths prevented was attributable to changes in the treatment in the acute phase and in secondary prevention treatments: the largest contributions came from treatment of 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 changes 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 BMI and diabetes would not have increased. The benefits from treatments were fairly equitable whereas the contribution from risk factor changes differed across socioeconomic groups. The model failed to explain approximately 28% of the mortality fall.

Conclusions: CHD mortality has recently halved in The Netherlands. Equally large contributions to the fall in CHD mortality have come from the increased use of acute and secondary prevention treatments and from improvements in population risk factors (including primary prevention treatments with cardiovascular drugs). Fewer patients developed CHD over time, but those who did tended to live longer. Quality of life, healthy life years and compression of CHD morbidity becomes increasingly important to reduce the future burden of CHD. Primary prevention strategies should go together with secondary prevention efforts to ensure a continuing decline in CHD mortality and morbidity in the future.