What should be done about asymptomatic hypercholesterolaemia?

Serum cholesterol and acute myocardial infarction: a case-control study from the GISSI-2 trial. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto-Epidemiologia dei Fattori di Rischio dell'Infarto Miocardico Investigators

OBJECTIVE

To examine the role of serum cholesterol in acute myocardial infarction in a population of patients with no history of coronary heart disease and to establish the nature of this association, the degree of risk, and the possible interaction between serum cholesterol and other major risk factors for acute myocardial infarction.

DESIGN

Case-control study.

SETTING

90 hospitals in northern, central, and southern Italy.

PATIENTS

916 consecutive cases of newly diagnosed acute myocardial infarction and 1106 hospital controls admitted to hospital with acute conditions not related to known or suspected risk factors for coronary heart disease.

DATA COLLECTION

Data were collected with a structured questionnaire and blood samples were taken by venepuncture as soon as possible after admission to hospital from cases and controls. Blood cholesterol concentrations were available for 614 cases and 792 controls.

RESULTS

After adjustment by logistic regression for sex, age, education, geographical area, smoking status, body mass index, history of diabetes and hypertension, and family history of coronary heart disease the estimated relative risks of acute myocardial infarction for quintiles of serum cholesterol (from lowest to highest) were 2.3 (95% confidence interval (CI) 1.6 to 3.4), 3.1 (95% CI 2.1 to 4.6), 4.1 (95% CI 2.8 to 6.0), and 5.2 (95% CI 3.5 to 7.7). The estimated relative risk across selected covariates increased from the lowest to the highest quintile of serum cholesterol particularly for men, patients under 55 years of age, and smokers. When the possible interaction of known risk factors with serum cholesterol was examined, smoking habits, diabetes, and hypertension had approximately multiplicative effects on relative risk.

CONCLUSIONS

This study indicates that serum cholesterol was an independent risk factor for acute myocardial infarction. This association was linear, with no threshold level. Moreover, there was a multiplicative effect between cholesterol and other major risk factors on the relative risk of acute myocardial infarction.

Familial hypercholesterolaemia: pilot study to identify children at risk

AIMS

To evaluate a more effective method of identifying children with familial hypercholesterolaemia by screening a population at high risk.

METHODS

Domiciliary measurement of random cholesterol concentration was made in 200 children who were first or second degree relatives of subjects with premature onset coronary artery disease. Measurements were taken by a health visitor using a portable analyser.

RESULTS

Twelve new cases of familial hypercholesterolaemia were identified during the first nine months of the study. Random cholesterol concentrations were within the normal range (< 5.2 mmol/l) in 70.5% of samples tested. Forty two (21%) of patients tested had a borderline cholesterol (5.2-5.9 mmol/l) but 50% of these fell within the normal range when fasting capillary samples were analysed. Children with significant hypercholesterolaemia on random testing (concentrations of > 5.9 mmol/l) (8.5%) also had fasting venous blood assayed for high density lipoprotein (HDL) cholesterol and tri-glyceride in the laboratory. Results indicated that 6.5% of patients screened were at high risk of cardiovascular disease (ratio of total: HDL cholesterol of > 4.5), and 1% had a moderately increased risk (ratio 3.5-4.5).

CONCLUSIONS

Children with familial hypercholesterolaemia can be identified from a selected "high risk" population by measuring random capillary cholesterol concentration.

Risk of fatal coronary heart disease in familial hypercholesterolaemia. Scientific Steering Committee on behalf of the Simon Broome Register Group

OBJECTIVES

(a) To determine the excess mortality from all causes and from coronary heart disease in patients with familial hypercholesterolaemia; (b) to examine how useful various criteria for selective measurement of cholesterol concentration in cardiovascular screening programmes are in identifying these patients.

DESIGN

Prospective cohort study.

SETTING

Eleven hospital outpatient lipid clinics in the United Kingdom.

PATIENTS

282 men and 244 women aged 20-74 with heterozygous familial hypercholesterolaemia.

MAIN OUTCOME MEASURE

Standardised mortality ratio, all adults in England and Wales being taken as standard (standardised mortality ratio = 100 for standard population).

RESULTS

The cohort was followed up for 2234 person years during 1980-9. Fifteen of the 24 deaths were due to coronary heart disease, giving a standardised mortality ratio of 386 (95% confidence interval 210 to 639). The excess mortality from this cause was highest at age 20-39 (standardised mortality ratio 9686; 3670 to 21,800) and decreased significantly with age. The standardised mortality ratio for all causes was 183 (117 to 273) and also was highest at age 20-39 (standardised mortality ratio 902; 329 to 1950). There was no significant difference between men and women. Criteria for measurement of cholesterol concentration in cardiovascular screening programmes (family history, presence of myocardial infarction, angina, stroke, corneal arcus, xanthelasma, obesity, hypertension, diabetes, or any of these) were present in 78% of patients.

CONCLUSIONS

Familial hypercholesterolaemia is associated with a substantial excess mortality from coronary heart disease in young adults but may not be associated with a substantial excess mortality in older patients. Criteria for selective measurement of cholesterol concentration in cardiovascular screening programmes identify about three quarters of patients with the clinically overt condition.