The rate of mental disorders among children and adolescent has doubled in the Calgary Health Region over the last 15-years.

To examine prevalence of depression in children and adolescent and determine the most frequent ICD diagnosis given a physician-assigned depression diagnosis.

We examined the annual and 15-year cumulative prevalence of major depression in a population of children and adolescent in the Calgary Health Region and determined the most frequent diagnosis of physical disorders given a depression diagnosis.

We used direct physician billing data for the Calgary health region (Calgary, Alberta) from 1994-2009 for treatment of any presenting concern (n = 763449). We identified 537 unique individuals (191 males) with a physician-assigned diagnosis of major depression. Odds ratios were used to identify the most frequent physical disorders given a depression diagnosis.

The 15-year cumulative prevalence among help-seeking population for major depression was 22.6 per 10,000. The annual rates of major depression increased twofold from 1.7 to 4.5 per 10,000. The cumulative prevalence rates of major depression were 29 (CI 26-33) per 10,000 for females and 16 (CI 14-18) per 10,000 for males. ICD codes under injury and poisoning were found to have the highest odds ratio followed by genitourinary system in relation to Major Depression diagnosis.

The twofold increase of major depression is consistent with the overall doubling of mental disorders among children and adolescent in the Calgary health region and has important planning and policy implications.