Prevalence of three lifestyle factors among Australian adults from 2004 to 2018: An age–period–cohort analysis

Background: It has been reported that current smoking, overweight/obesity and physical inactivity are significant modifiable risk factors of all-cause mortality, cardiovascular disease and cancer. However, the effects of age, period and cohort on the prevalence of the three lifestyle factors among Australian adults are still unclear.

Methods: Our study analysed data from 2004 to 2005, 2007 to 2008, 2011 to 2012, 2014 to 2015 and 2017 to 2018 National Health Survey. We employed the age–period–cohort models to analyze the individual effects of age, period and cohort on the prevalence of current smoking, overweight/obesity and physical inactivity among Australian adults.

Results: A total of 76 489 adults were included. Age, period and cohort all showed significant independent effects on prevalence of current smoking, overweight/obesity and physical inactivity (P < 0.01) except the cohort effect on physical inactivity in females (P = 0.31). The prevalence of current smoking decreased with age and period, and it first increased with birth cohort and then declined. For overweight/obesity prevalence, it increased with age until early-60s and then dropped. We found a positive period effect on overweight/obesity; however, the prevalence of overweight/obesity experienced several shifts with birth cohort. Physical activity prevalence raised with age, and it has several fluctuations for curves of period and cohort.

Conclusion: Age effects showed a distinct pattern for the prevalence of the three lifestyle factors. The prevalence of overweight/obesity continued to rise during the study period. The raised physical inactivity prevalence in recent study cycles is also concerning. Recent birth cohorts may be at increased risk of overweight/obesity and physical inactivity.