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Wednesday, September 18, 2013

Latest information on the prevalence of major depression in Canada

In 2012, Statistics Canada conducted a national mental health survey. This is the second such survey to be conducted in Canada. The first was conducted in 2002. On September 18th, 2013 they released a "Health at a Glance" paper to summarize the results. With respect to the condition of interest to this blog, the prevalence of major depression is reported as stable since 2002 at 5%. A link to the paper can be found here. On the one hand, this is good news, since it does not confirm fears that there is an epidemic of depression in Canada. This is not surprising, see this paper on secular trends. However, it it a cause for concern that the prevalence is not decreasing, despite presumably improving awareness, mental health literacy and access to treatment.

Risk of depression: the past predicts the future

In recent posts, I have noted recent attempts to develop algorithms capable of predicting recurrences in major depression. My colleague, Dr. Jian Li Wang, has been working on developing such algorithms and his work extends similar work done previously by the PredictD study group. However, these algorithms are complex and can be difficult to apply. Dr. Andrew Bulloch, at the University of Calgary has recently shown (link to article synopsis here) that a very simple rule can work quite well. Using Canadian epidemiological data, he has shown that the number of prior episodes is a good predictor and that the risk of future episodes has a linear relationship to the number of past episodes. While this is not surprising, the strength of association is very strong and this may be a strong and simple predictive rule.