The impact of a healthy lifestyle on Disability-Adjusted Life Years: a prospective cohort study

BACKGROUND The association between single health behaviours and incidence of and premature mortality from major chronic diseases, including myocardial infarction, stroke, diabetes mellitus, and cancer, has been demonstrated thoroughly. However, the association of several healthy behaviours with Disability-Adjusted Life Years (DALYs), which is a measure for total health combining Years Lost due to Disability and the Years of Life Lost due to premature mortality, has not been studied yet. METHODS A prospective cohort study was conducted among 33,066 healthy men and women aged 20 to 70 years recruited into the EPIC-NL study during 1993 to 1997. Participants' smoking status, BMI, physical activity, and adherence to a Mediterranean-style diet (excluding alcohol) were investigated separately and combined into a simple health behaviour score ranging from 0 to 4. Participants were followed until the end of 2007 for occurrence of and mortality from the most important chronic diseases. The association between lifestyle (separate lifestyle factors and a simple health behaviour score) and DALYs were adjusted for relevant confounders. RESULTS After a median follow-up of 12.4 years, 6,647 disease incidences and 1,482 deaths were documented. Non-smoking, low BMI (BMI <25), being physically active, and adherence to a Mediterranean diet were all associated with a significantly lower disease burden. Persons adhering to all four healthy lifestyle characteristics lived a minimum of 2 years longer in good health (DALYs: -2.13; 95% CI: -2.65 to -1.62) than persons with none. Due to our non-extinct cohort, the total number of DALYs, and consequently the estimates, is underestimated. Therefore, true lifetime health benefits of a healthy lifestyle will be even larger. CONCLUSIONS Non-smoking, a low BMI, being physically active, and adherence to a Mediterranean diet were associated with a lower disease burden. Each additional healthy lifestyle factor contributed to a longer life in good health.