Is the volume-outcome relationship sustained in psychiatric care?

Background: Although much prior research has found a consistently positive volume-outcome relationship, there is scanty documentation on this issue in mental healthcare. This study examines the association between a hospitals' psychiatric inpatient volume and 30-day readmission rates. Methods: Using administrative data from Taiwan's National HealthInsurance Research Database for 2003, the likelihood of 30-day readmission is examined relative to the hospital's volume of voluntary psychiatric admissions and total bed-days. Results: As hospital volume increases, so too does the 30-day readmission rates for patients with schizophrenia, bipolar disorder and major depressive disorders. Conclusions: The positive volume-outcome relationship in patients suffering from psychiatric disorders suggests a different scenario from the 'practice makes perfect' phenomenon that may underlie the inverse volume-outcome relationship found among most physical disorders, both surgical and medical.