November 12, 2010PLoS ONE110 citationsOpen Access
Analysing the Large Decline in Coronary Heart Disease Mortality in the Icelandic Population Aged 25-74 between the Years 1981 and 2006
Key Result
Between 1981 and 2006, 73% of the 80% decline in coronary heart disease mortality in Iceland was attributable to reductions in major cardiovascular risk factors, while 25% was attributable to medical treatments.
Study Design
Type
Observational (n=177,364)
Structured PICO
How much of the decrease in coronary heart disease mortality in Iceland between 1981 and 2006 can be attributed to medical/surgical treatments versus changes in cardiovascular risk factors?
P
Population
177,364 Icelandic men and women aged 25 to 74 years, analyzed to determine the causes of the 80% decrease in coronary heart disease mortality between 1981 and 2006.
E
Exposure
Medical and surgical treatments and changes in cardiovascular risk factors
O
Outcome
Coronary heart disease mortalityhard clinical
Almost three quarters of the 80% decline in coronary heart disease mortality in Iceland between 1981 and 2006 was attributable to population-level reductions in major cardiovascular risk factors, emphasizing the value of comprehensive prevention strategies.
Main Result
Effect estimate: 73% (95% CI 54-93)
Limitations
- Modeling studies represent crude simplifications of a complex reality.
- Dependence on the variable extent and quality of data available on CHD risk factor trends and treatment uptakes.
- The model included only adults aged 25 to 74 years old due to very limited data in older groups.
- Solid data on salt or sodium intake on a population level were not available.
Abstract
BACKGROUND: Coronary heart disease (CHD) mortality rates have been decreasing in Iceland since the 1980s. We examined how much of the decrease between 1981 and 2006 could be attributed to medical and surgical treatments and how much to changes in cardiovascular risk factors. METHODOLOGY: The previously validated IMPACT CHD mortality model was applied to the Icelandic population. The data sources were official statistics, national quality registers, published trials and meta-analyses, clinical audits and a series of national population surveys. PRINCIPAL FINDINGS: Between 1981 and 2006, CHD mortality rates in Iceland decreased by 80% in men and women aged 25 to 74 years, which resulted in 295 fewer deaths in 2006 than if the 1981 rates had persisted. Incidence of myocardial infarction (MI) decreased by 66% and resulted in some 500 fewer incident MI cases per year, which is a major determinant of possible deaths from MI. Based on the IMPACT model approximately 73% (lower and upper bound estimates: 54%-93%) of the mortality decrease was attributable to risk factor reductions: cholesterol 32%; smoking 22%; systolic blood pressure 22%, and physical inactivity 5% with adverse trends for diabetes (-5%), and obesity (-4%). Approximately 25% (lower and upper bound estimates: 8%-40%) of the mortality decrease was attributable to treatments in individuals: secondary prevention 8%; heart failure treatments 6%; acute coronary syndrome treatments 5%; revascularisation 3%; hypertension treatments 2%, and statins 0.5%. CONCLUSIONS: Almost three quarters of the large CHD mortality decrease in Iceland between 1981 and 2006 was attributable to reductions in major cardiovascular risk factors in the population. These findings emphasize the value of a comprehensive prevention strategy that promotes tobacco control and a healthier diet to reduce incidence of MI and highlights the potential importance of effective, evidence based medical treatments.