Revisiting lifestyle risk index assessment in a large Australian sample: should sedentary behavior and sleep be included as additional risk factors?

Objective: Most studies on multiple health behaviors include physical inactivity, alcohol, diet, and smoking (PADS), with few including emerging lifestyle risks such as sleep or sitting. We examined whether adding sitting and sleep to a conventional lifestyle risk index improves the prediction of cross-sectional health outcomes (self-rated health, quality of life, psychological distress, and physical function). We also explored the demographic characteristics of adults with these multiple risk behaviors.

Methods: We used baseline data of an Australian cohort study (n=191,853) conducted in 2006-2008 in New South Wales. Lifestyle risk index was operationalized as 1) PADS, 2) PADS+sitting, 3) PADS+sleep, and 4) PADS+sitting+sleep. We estimated receiver operating characteristic curve for self-reported binary health outcomes and calculated the area under the curve to illustrate how well each index classified the outcome. We used multiple logistic regression to determine the demographic characteristics of adults with multiple lifestyle risks.

Results: Adding sleep duration but not sitting time to the PADS index significantly improved the classification of all health outcomes. Men, those aged 45-54years, those with 10 years of education or less, and those living in regional/remote areas had higher odds of multiple risk behaviors.

Conclusions: Future research on multiple health behaviors might benefit from including sleep as an additional behavior. In Australia, unhealthy lifestyles tend to cluster in adults with certain demographic characteristics.