Sudden unexpected cardiac death among Tasmanian men

Excess coronary mortality among Australian men and women living outside the capital city statistical divisions

OBJECTIVES

To compare rates of mortality from coronary heart disease (CHD) between populations living within and outside Australian capital city statistical divisions.

DESIGN AND SETTING

Descriptive epidemiological study based on data for all residents of Australia aged 30-69 years who died between 1986 and 1996 in all States and Territories of Australia.

MAIN OUTCOME MEASURES

Standardised mortality rates from all causes and coronary heart disease as coded by the Australian Bureau of Statistics, and estimated excess deaths in populations living outside capital city statistical divisions.

RESULTS

Between 1986 and 1996, mortality from CHD declined by 46% in men and 51% in women, and accounted for 61% of the decline in mortality from all causes in men and 48% in women. More deaths than expected from acute myocardial infarction resulted in mortality rates from CHD up to 30% higher in men and 21% higher in women living outside the capital city statistical divisions, and accounted for an overall estimated excess of 3835 deaths from CHD in men (32% of excess deaths from all causes), and 1385 deaths from CHD in women (27% of excess deaths from all causes) over the 11-year study period.

CONCLUSIONS

Although there were impressive declines in coronary mortality in all Australian States and Territories from 1986 to 1996, populations living outside capital cities continue to have higher death rates from CHD. These differences in mortality rates indicate a need for further research into factors which may influence mortality rates for CHD in rural and remote areas, and immediate measures to ensure optimal treatment of coronary risk factors and acute coronary events in such populations.

Risk factors for sudden unexpected cardiac death in Tasmanian men

BACKGROUND

Sudden unexpected cardiac death (SUCD) accounts for approximately 25% of deaths from ischaemic heart disease (IHD) but is relatively poorly understood because of the difficulties involved in researching aetiology. Clinical differences between instances of SUCD and those cases of acute chest pain that survive long enough to be proven as myocardial infarction but are eventually fatal might reflect differences in aetiology.

AIMS

To determine the risk factors for sudden unexpected cardiac death in Tasmanian men.

METHODS

A population-based case-control method was used with the study population, an estimated 125,225 men aged 25-74 years living in the island State of Tasmania, Australia. The case group of 102 men who had a SUCD was validated using necropsy reports, hospital records and information provided by the usual general practitioner. Cases were matched with 204 community controls. Spouses or partners of eligible subjects answered a detailed questionnaire. Multi-variate odds ratios (ORs) for risk factors were calculated using stepwise analysis.

RESULTS

Risk factors measured included: smoking habit, treated hypertension, hypercholesterolaemia, diabetes mellitus, family history of IHD, alcohol intake and exercise habits. Independent risk factors for SUCD were: history of diabetes mellitus (OR = 4.2, 95% CI: 1.39, 12.81), current smoking status (OR = 3.5, 95% CI: 1.80, 6.82), and family history of IHD (OR = 2.6, 95% CI: 1.34, 4.92).

CONCLUSIONS

Some accepted risk factors for acute myocardial infarction (AMI) also predict sudden death in men with no history of coronary disease. Efforts to reduce smoking, the incidence of diabetes mellitus and mean blood pressure must be continued as SUCD is, by definition, untreatable but is potentially avoidable in many instances.