The projected effect of risk factor reduction on major depression incidence: A 16-year longitudinal Canadian cohort of the National Population Health Survey

Background: Few studies have examined the effect of risk factor modification on depression incidence. This study estimated the effect of risk factor modification on depression incidence. Methods: Data analyzed were from the Canadian National Population Health Survey (NPHS) - a longitudinal population-based cohort study. The study followed-up a national cohort sample over a 16-year period from 1994 to 2010. Multivariate modified Poisson regression was used to estimate relative risk. Results: The cumulative incidence rate of depression during the 16-year follow-up was 12.07%. Being younger adult, female, Caucasian, poor, occasional/abstainer/former drinker, regular smoker, and having chronic disease were significantly associated with an increased risk of developing depression. About 40% of depression incidence (850,000 cases) was potentially attributable to modifiable risk factors (poor income, smoking, and having a chronic disease). A 10% reduction in the prevalence of these modifiable risk factors could potentially prevent about 165,000 cases of depression. Limitations: The calculation of PAFs assumes that there is a causal relationship between a risk factor and depression. However, major depression has multiple causes. The potential effect of risk factor modification on depression incidence may vary by the profile of risk factors assessed in a particular study. Several potentially important risk factors were not included in this study. Conclusion: Public health campaigns targeted at significant modifiable risk factors could have a profound effect on future depression incidence. Prevention trials are needed to directly evaluate the effect of single and/or multiple risk factors modification on depression incidence. (C) 2014 Elsevier B.V. All rights reserved,