# Health Reports Trends in the prevalence of depression and anxiety disorders among working-age Canadian adults between 2000 and 2016

by Kathleen G. Dobson, Simone N. Vigod, Cameron Mustard, and Peter M. Smith

Release date: December 16, 2020

### Limitations

The MDE module was optional in the annual CCHS cycles and was administered at the discretion of provincial health regions. This resulted in a reduced sample size, reduced generalizability to the Canadian labour force population, and a limited ability to explore labour force subpopulations. Compared with the CCHS participants whose questionnaires included the MDE module (i.e., participants who were included in the sample), CCHS participants whose questionnaires did not contain the module generally had a similar demographic profile. However, there was a trend that participants who did not receive the MDE module may have had higher distress levels (as measured by the Kessler Psychological Distress Scale), and more participants may have self-reported mood or anxiety disorder diagnoses. This would suggest that any bias associated with the reduced sample size would lead to an underestimation in the findings.

The continuity of the annual CCHS cycles may have also introduced bias into the study. The annual CCHS underwent a sampling redesign and survey content change in 2015, which may have resulted in a different demographic profile compared with previous CCHS cycles. To account for this difference, the study used a random-effects meta-analytic design that models within-cycle error and between-cycle error. Generally, the proportion of participants in each labour force group and responses on mental health measures were similar to previous cycles.

The differences in MDE measurement tools may have also introduced measurement bias. The 2015 to 2016 CCHS cycle used a different MDE instrument (the PHQ-9) compared with previous annual cycles. A sensitivity analysis was conducted that excluded these CCHS cycles, and the results showed that estimates that were originally statistically significant remained so. Pooled prevalence estimates were similar, but slightly smaller when the 2015 to 2016 CCHS cycle was excluded. Although not statistically different from other estimates, the MDE prevalence estimates calculated by the WMH-CIDI in the 2002 and 2012 CCHS cycles were lower than those calculated with the CIDI-SF and PHQ-9.

Because anxiety disorders were self-reported, they may be underestimated—particularly in the earlier CCHS cycles when these disorders may have been slightly more stigmatized. Further, there may be bias associated with exploring a combined measure of depressive symptoms versus a self-reported anxiety disorder diagnosis. However, when an indicator of self-reported mood disorder diagnosis was explored, results showed similar magnitudes and trends.

Certain characteristics of the mental illnesses studied—combined with employment status—may have made participants less likely or willing to share their mental health information or to participate in the CCHS at all. This may have caused prevalence underestimations in these groups.

Lastly, the participation rate in the CCHS has decreased over time. However, any bias associated with this decrease would be assumed to be non-differential across labour force groups and survey weights developed by Statistics Canada were used to try to minimize this bias.

## Conclusions

Between the early 2000s and 2016, the prevalence of an annual MDE was approximately 5.4%, the presence of an anxiety disorder was 4.6%, and presence of an anxiety disorder and a MDE was approximately 1.2% among working-aged employed Canadians. These estimates were higher among participants who were unemployed and those not participating in the labour force. MDE prevalence remained stable between 2000 and 2016, although there was a modest increase in self-reported medically diagnosed anxiety disorders. Findings also highlight existing limitations of national surveillance data to explore the mental health of labour force participants.

## Implications

The COVID-19 pandemic has caused changes in distress and in labour force displacement among the Canadian population.Note 45Note 46Note 47 This study found higher average MDE and anxiety disorder prevalence among unemployed Canadians and Canadians not participating in the labour force, stable MDE prevalence trends over time among each labour force group, and an increase in anxiety disorder diagnosis prevalence across all labour force groups. In the context of COVID-19, the results of this study are critical to informing equitable mental health, workplace and labour policies to retain and integrate Canadians with mental illnesses in the labour force during and after the pandemic. This study also highlights important gaps in existing data regarding the study of depression and anxiety among the Canadian labour force at the population level.

### Conflict of interest

None of the authors have any conflicts of interest to declare.

## Acknowledgments

This work was supported by a Canadian Institutes for Health Research Doctoral Research Award awarded to Ms. Dobson. The authors would also like to acknowledge the support from the Canadian Research Data Centres Network, the Statistics Canada Research Data Centre in the Toronto region, Statistics Canada and all the survey participants who made this work possible.

References

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