Using readmission rates as indicators of outcome in comparing psychiatric services

Patients with more than one ICD-9 diagnosis may require more admissions than do inpatients with single disorders. Rates of readmission were judged by either the number of admissions in the year following any dual diagnosis or by the interval to the next readmission (if any). Such rates were significantly higher for patients with second diagnoses of alcohol or drug dependence, compared to other dual diagnosis patients matched for a common mental health disorder or compared to patients with single diagnoses. Patients with schizophrenia were especially prone to readmission, if secondary alcohol or drug dependence was ever recorded.