Is there seasonality in hospitalizations for major depressive disorder in Canada?

Background — Canada, a temperate country with four defined seasons incurs an annual productivity loss of over $30 billion on major depressive disorder (MDD); however it remains unknown whether inpatient hospitalization for MDD exhibits seasonal variations.

Objective — Our study objective was to determine if there are seasonal variations in hospitalization rates for MDD in Canada.

Methods — We used time series analysis to determine monthly rates of hospitalizations for MDD from 2006 – 2013, on data from population level health-administrative databases in Ontario, Canada. We also stratified analysis by gender and three age groups: 18 to 39, 40 to 65 and those over 65. We compared demographic and comorbidity profiles of patients admitted in April, August and December to elucidate if patient characteristics differed by season of admission.

Results — We identified a total of 130,336 admissions for MDD for 95,439 unique patients. Baseline characteristics of the patients were similar across seasons. We did not detect significant seasonality of hospitalizations for MDD across any of the gender or age subgroups.

Discussion — Our results question the popularly held belief that hospitalizations for MDD vary with seasons. These findings highlight the need for uniform hospital resource allocation for MDD throughout the year in Canada.