Mild myocardial infarction - A classification problem in epidemiologic studies

In studies assessing the trends in coronary events, such as the World Health Organization (WHO) MONICA Project (multinational MONItoring of trends and determinants of CArdiovascular disease), the main emphasis has been on coronary deaths and non-fatal definite myocardial infarctions (MI). It is, however, possible that the proportion of milder MIs may be increasing because of improvements in treatment and reductions in levels of risk factors. We used the MI register data of the WHO MONICA Project to investigate several definitions for mild non-fatal MIs that would be applicable in various settings and could be used to assess trends in milder coronary events. Of 38 populations participating in the WHO MONICA MI register study, more than half registered a sufficiently wide spectrum of events that it was possible to identify subsets of milder cases. The event rates and case fatality rates of MI are clearly dependent on the spectrum of non-fatal MIs, which are included. On clinical grounds we propose that the original MONICA category ''non-fatal possible MI'' could bt:divided into two groups: ''non fatal probable MI'' and ''prolonged chest pain.'' Non-fatal probable MIs are cases, which in addition to ''typical symptoms'' have electrocardiogram (EGG) or enzyme changes suggesting cardiac ischemia, but not severe enough to fulfil the criteria for non-fatal definite MI In more than half of the MONICA Collaborating Centers, the registration of MI covers these milder events reasonably well. Proportions of non-fatal probable MIs vary less between populations than do proportions of non fatal possible MIs. Also rates of non-fatal probable MI are somewhat more highly correlated with rates of fatal events and non-fatal definite MI. These findings support the validity of the category of non-fatal probable MI. In each center the increase in event rates and the decrease in case-fatality due to the inclusion of non-fatal probable MI was lar er for women than men. For the WHO MONICA Project and other epidemiological studies the proposed category of non-fatal probable MIs can be used for assessing trends in rates of milder MI. Copyright (C) 1997 Elsevier Science Inc.

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 LHD, 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.

A review of health effects of aircraft noise

Social surveys have established dose-response relationships between aircraft noise and annoyance, with a number of psychological symptoms being positively related to annoyance. Evidence that exposure to aircraft noise is associated with higher psychiatric hospital admission rates is mixed. Some evidence exists of an association between aircraft noise exposure and use of psychotropic medications. People with a pre-existing psychological or psychiatric condition may be more susceptible to the effects of exposure to aircraft noise. Aircraft noise can produce effects on electroencephalogram sleep patterns and cause wakefulness and difficulty in sleeping. Attendances at general practitioners, self-reported health problems and use of medications, have been associated with exposure to aircraft noise, but some findings are inconsistent. Some association between aircraft noise exposure and elevated mean blood pressure has been observed in cross-sectional studies of schoolchildren, but with little confirmation from cohort studies. There is no convincing evidence to suggest that all-cause or cause-specific mortality is increased by exposure to aircraft noise. There is no strong evidence that aircraft noise has significant perinatal effects. Using the World Health Organization definition of health, which includes positive mental and social wellbeing, aircraft noise is responsible for considerable ill-health. However, population-based studies have not found strong evidence that people living near or under aircraft flight paths suffer higher rates of clinical morbidity or mortality as a consequence of exposure to aircraft noise. A dearth of high quality studies in this area precludes drawing substantive conclusions.