Trends and projections of cause-specific premature mortality in Australia to 2044: a statistical modelling study

Background

Long-term projections of premature mortality (defined as deaths age <75 years) help to inform decisions about public health priorities. This study aimed to project premature mortality rates in Australia to 2044, and to estimate numbers of deaths and potential years of life lost (PYLL) due to premature mortality overall and for 59 causes.

Methods

We examined the past trends in premature mortality rates using Australian mortality data by sex, 5-year age group and 5-year calendar period up to 2019. Cigarette smoking exposure data (1945-2019) were included to project lung cancer mortality. Age-period-cohort or generalised linear models were developed and validated for each cause to project premature mortality rates to 2044.

Findings

Over the 25-year period from 1990-1994 to 2015-2019, there was a 44.4% decrease in the overall age-standardised premature mortality rate. This decline is expected to continue, from 162.4 deaths/100,000 population in 2015-2019 to 141.7/100,000 in 2040-2044 (12.7% decrease). Despite declining rates, total numbers of premature deaths are projected to increase by 22.8%, rising from 272,815 deaths in 2015-2019 to 334,894 deaths in 2040-2044. This is expected to result in 1.58 million premature deaths over the 25-year period 2020-2044, accounting for 24.5 million PYLL. Of the high-level cause categories, cancer is projected to remain the most common cause of premature death in Australia by 2044, followed by cardiovascular disease, external causes (including injury, poisoning, and suicide), and respiratory diseases.

Interpretation

Despite continuously declining overall premature mortality rates, the total number of premature deaths in Australia is projected to remain substantial, and cancer will continue to be the leading cause. These projections can inform the targeting of public health efforts and can serve as benchmarks against which to measure the impact of future interventions. They emphasise the ongoing importance of accelerating the prevention, early detection, and treatment of key health conditions.

Funding

No funding was provided for this study.

Lung cancer mortality in Australia in the twenty-first century: How many lives can be saved with effective tobacco control?

OBJECTIVES

To estimate the number of past and future lung cancer deaths that have already been averted by tobacco control initiatives in Australia, and to estimate the number of additional deaths averted under various smoking scenarios.

METHODS

We predicted lung cancer mortality rates and case numbers to 2100 using a previously validated generalized linear model based on age, birth cohort and population cigarette smoking exposure. We estimated the impact of various tobacco control scenarios: 'actual tobacco control' (incorporating the aggregate effect of past and current taxation, plain packaging, mass media campaigns and other initiatives) and scenarios where 10%, 5% and 0% smoking prevalence was achieved by 2025, all of which were compared to a counterfactual scenario with the highest historical smoking consumption level continuing into the future as if no tobacco control initiatives had been implemented.

RESULTS

Without tobacco control, there would have been an estimated 392,116 lung cancer deaths over the period 1956-2015; of these 20% (78,925 deaths; 75,839 males, 3086 females) have been averted due to tobacco control. However, if past and current measures continue to have the expected effect, an estimated 1.9 million deaths (1,579,515 males, 320,856 females; 67% of future lung cancer deaths) will be averted in 2016-2100. If smoking prevalence is reduced to 10%, 5% or 0% by 2025, an additional 97,432, 208,714 or 360,557 deaths could be averted from 2016 to 2100, respectively.

CONCLUSION

Tobacco control in Australia has had a dramatic impact on the number of people dying from lung cancer. Several hundred thousand more lung cancer deaths could be averted over the course of the century if close-to-zero smoking prevalence could be achieved in the next decade.

Lung cancer mortality in Australia: Projected outcomes to 2040

OBJECTIVES

The aim was to develop and validate a statistical model which uses past trends for lung cancer mortality and historical and current data on tobacco consumption to project lung cancer mortality rates into the future for Australia.

METHODS

We used generalized linear models (GLMs) with Poisson distribution including either age, birth cohort or period, and/or various measures of population tobacco exposure (considering cross-sectional smoking prevalence, cigarettes smoked and tar exposure per capita). Sex-specific models were fitted to data for 1956-2015 and age-standardized lung cancer mortality rates were projected forward to 2040. Possible lags of 20-30 years between tobacco exposure and lung cancer mortality were examined. The best model was selected using analysis of deviance. To validate the selected model, we temporarily re-fitted it to data for 1956-1990 and compared the projected rates to 2015 with the observed rates for 1991-2015.

RESULTS

The best fitting model used information on age, birth cohort and tar exposure per capita; close concordance with the observed data was achieved in the validation. The forward projections for lung cancer mortality using this model indicate that male and female age-standardized rates will decline over the period 2011-2015 to 2036-2040 from 27.2 to 15.1 per 100,000, and 15.8 to 11.8 per 100,000, respectively. However, due to population growth and ageing the number of deaths will increase by 7.9% for males and 57.9% for females; from 41,040 (24,831 males, 16,209 females) in 2011-2015 to 52,403 (26,805 males, 25,598 females) in 2036-2040.

CONCLUSION

In the context of the mature tobacco epidemic with past peaks in tobacco consumption for both males and females, lung cancer mortality rates are expected to continually decline over the next 25 years. However, the number of lung cancer deaths will continue to be substantial, and to increase, in Australia's ageing population.