Prevalence of depressive, bipolar and adjustment disorders, in Quebec, Canada.

Background: The prevalence of mood disorders was estimated at 5.4% according to the latest Canadian survey. It has been suggested to use administrative data and self-reported data to optimize the estimation for mental health care in the population. Using administrative data, algorithms (combination of codes from the International Classification of Diseases) had been previously developed to identify the population with mood and anxiety disorders. However, the specific prevalence of each component of mood disorders (depressive, bipolar and adjustment disorders) are still unknown in Quebec, Canada.

Objective: To 1) identify the population diagnosed respectively with depressive, bipolar and adjustment disorders in administrative data, and 2) provide annual prevalence estimates of each component.

Method: Data were extracted from the Quebec Integrated Chronic Disease Surveillance System and the entire population of Quebec (2000-2017) was included in this study (8.3 million; 2017). The prevalence of depressive, bipolar and adjustment disorders were estimated using specific algorithms.

Results: The annual prevalence of depressive disorders was 3.7% in 2000-2001; it decreased to 2.8% in 2016-2017. In comparison, the prevalence of bipolar disorders was 0.8% in 2000-2001, decreasing to 0.6% in 2016-2017, and the prevalence of adjustment disorders was 1.3% in 2000-2001 and increased to 1.6% in 2016-2017.

Conclusion: Using specific algorithms, we observed that the trend of adjustment disorders is increasing while trends of depressive and bipolar disorders are decreasing. Further studies should assess if the related burden of care respectively follows the same trends as policy makers' allocations of resources may need to be adapted.