The temporal order of comorbidity between psychiatric disorder and other biomedical disorders (e.g., ulcerative colitis, cancer) was examined.

Direct physician billing data for the Calgary, Alberta from 1994-2009 for treatment of any presenting concern resulting in an International International Classification of Disease (ICD) diagnosis in the Calgary health zone (n = 763449) were used to identify individuals with ulcerative colitis (UC) or neoplasms. The counts of individuals with and without these disorders were tallied and grouped on the basis of the order of the psychiatric disorder and UC or neoplasm. Odds ratios and 95% confidence intervals were calculated and compared along with the annual and cumulative prevalences within each grouping.

In all age groups, neuroses/depression grouping diagnoses were significantly most likely to arise before UC for males (Odds Ratio 1.87) and females (Odds Ratio 2.24). Among children, psychoses were between 3 and 11 times more likely to arise prior to pedicatric neoplasm.

The temporal association between psychiatric disorder and the examined bimedical disorders provides novel insight into the etiology of these disorders and has implications related to their respective treatments.