Causes of death reviewed

Traditional analyses of causes of death in Australia – which focus on one underlying cause of death rather than multiple causes – can underestimate the contribution of some chronic diseases, according to a report released this week by the Australian Institute of Health and Welfare (AIHW).

The report, Multiple causes of death: an analysis of all natural and selected chronic disease causes of death 1997-2007, uses multiple causes of death statistics, reportedly for the first time, to describe patterns of chronic disease mortality in Australia. Multiple causes of death occur when two or more diseases or conditions are reported as contributing to a death.

“Some chronic diseases are more likely to be reported as an associated cause of death, rather than the main cause of death,” AIHW spokesperson, Ann Hunt, said.

“Traditional analysis ignores associated causes of death, and so underestimates the contribution of diseases such as chronic kidney failure, diabetes, asthma, dementia and Alzheimer diseases and chronic obstructive pulmonary disease to deaths in Australia,” she added.

On average, three diseases contributed to each death due to natural causes in Australia in 2007, and only 20% of these deaths were due to a single disease.

The report also showed an increase in the number of deaths where five or more causes contributed    were up from 11% to 21% between 1997 and 2007.

People aged 60 to 89 years, had the highest average number of diseases causing death, more so than younger people and the very old.

For deaths involving some chronic diseases, coronary heart disease (CHD), hypertensive diseases and diabetes were leading contributing causes.

“CHD contributed to nearly half of deaths involving diabetes, and more than one third involving chronic and unspecified kidney failure, chronic obstructive pulmonary disease or asthma,” Ms Hunt said.

One quarter of deaths involving dementia or Alzheimer disease also involved influenza or pneumonia.

“The use of multiple cause data gives a more complete picture of all diseases contributing to death, which can also support targeted prevention, treatment and service planning, inform surveillance, guide research investments and enhance health measures such as estimates of burden of disease.”