Polymorphism in high density lipoprotein paraoxonase gene and risk of acute myocardial infarction in men: prospective nested case-control study Commentary: Causality---the Achilles' heel of observational studies Commentary: How high density lipoprotein protects against heart disease

Abstract
Our prospective nested case-control study was carried out among participants in the Kuopio ischaemic heart disease risk factor study We examined 2682 (83%) of 3235 invited men aged 42, 48, 54 or 60 during 1984-9. Blood samples were collected and risk factors assessed at baseline. A DNA sample was available for this study for 1137 men who were free of coronary disease. We registered and verified all myocardial infarctions—definite or possible—between the baseline examinations and the end of 1995.3 The mean follow up time was 8.5 years, and in patients who had had multiple infarctions we considered only the first.