Smoking, low density lipoprotein cholesterol, fibrinogen and myocardial infarction before 41 years of age: a Danish case-control study.

Background Of major coronary risk factors, smoking and total cholesterol were significant in a previous Danish case-control study of myocardial infarction at a young age. Objective To determine whether smoking was an important coronary risk factor in the context of new and major anthropometric and biochemical risk factors for myocardial infarction in individuals less than 41 years of age. Methods A prevalence hospital-based matched case-control study of young individuals. We selected 22 Caucasian cases and 24 Caucasian controls without coronary heart disease matching for age and gender and studied a series of major coronary risk factors and newer anthropometric and biochemical variables. Results In conditional univariate logistic regression analyses, the following factors were significantly associated with the coronary risk: family history, social class, smoking, intraabdominal adipose tissue area as percentage of total abdominal adipose tissue area on a CT scan, glycosylated haemoglobin level, systolic blood pressure, total cholesterol, low density lipoprotein (LDL) cholesterol, homocysteine, and fibrinogen levels (P < 0.05). However, in multiple conditional logistic regression analyses, only smoking, LDL cholesterol, and fibrinogen levels remained significant. Ten cases (46%) and none of the 24 controls were smokers with a LDL cholesterol level 4.5 mmol/l and a fibrinogen level 3.7 g/l (P = 0.0003, Fisher's exact test). Conclusion Out of a series of major and newer coronary risk factors in young Western Caucasians, smoking, and levels of LDL cholesterol, and fibrinogen were independent significant coronary risk factors. The findings need to be validated in prospective studies. (C) 2002 Lippincott Williams Wilkins.