Dual diagnosis: A national study of psychiatric hospitalization patterns of people with developmental disability.

Objective: To report national demographics and diagnostic profiles of people with developmental disability hospitalized for psychiatric reasons, and to contrast results to psychiatric hospitalizations among patients with no comorbid developmental disability.

Method: People with developmental disability across Canada were identified using data administered by the Canadian Institute for Health Information. Among this cohort of people with developmental disability, records of hospitalization for psychiatric reasons were aggregated for the 2005/06 fiscal year (April 2005 to March 2006). Descriptive statistics on province of residence, age, sex, specific diagnoses, length of stay, and hospitalization frequency were calculated and compared with people without developmental disability.

Results: In Canada, people with developmental disability were hospitalized a total of 8378 times in 2005/06; among these, 3478 (42%) were for psychiatric conditions. The number of people with developmental disability hospitalized for a psychiatric condition represents about 2% of the general population hospitalized for such conditions. Among people with developmental disability hospitalized for a psychiatric condition most were men and people aged between 15 and 34 years. For almost all psychiatric disorder categories, people with developmental disability were hospitalized at rates significantly different than their counterparts without developmental disability. Lengths of hospital stays for psychiatric conditions were very similar when comparing the study groups; however, people with developmental disability were more likely to have 2 or more hospitalizations during the year.

Conclusions: People with developmental disability display unique hospitalization patterns, compared with the general population.