Estimated prevalence of the seasonal subtype of major depression in a Canadian community sample.
OBJECTIVE
To examine estimates of lifetime prevalence of seasonal affective disorder (SAD) in Toronto, Ontario.


METHODS
Random telephone numbers were generated for the city of Toronto, and 781 respondents completed a telephone interview. Trained nonphysician interviewers conducted all interviews, which involved structured questions for diagnosing major depression. Patterns of symptom change across seasons were evaluated to establish a diagnosis of SAD according to DSM-III-R criteria.


RESULTS
Correcting for sex and age, the prevalence of SAD defined by DSM-III-R criteria was 2.9% (95% CI, 1.7% to 4.0%), and the overall lifetime prevalence of major depression in the sample was 26.4% (95% CI, 23.3% to 29.4%). Some subjects were contacted for a follow-up interview conducted in person; the positive predictive value for the diagnosis of major depression for the telephone interview was 100%, and the negative predictive value was 93%.


CONCLUSIONS
The seasonal subtype of depression represents 11% of all subjects with major depression, suggesting that SAD is a significant public health concern. The telephone interview demonstrated adequate reliability, indicating that it is appropriate for epidemiological surveys of this nature.
Levitt
A J
AJ
University of Toronto, Department of Psychiatry. anthony.levitt@swchsc.on.ca
Boyle
M H
MH
Joffe
R T
RT
Baumal
Z
Z
D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D016574:Seasonal Affective Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D014505:Urban Population / Q000706:statistics & numerical data*