The Relationship Between Volume and Quality in Mental Health Care

The link between volume and quality has been repeatedly demonstrated across a variety of settings and health conditions. Is there a similar link between volume and quality in mental health care?

• A team that included RAND researchers developed a way to measure volume against performance for mental health care. They used data for the 384 health maintenance organizations participating in the Health Employer Data and Information Set (HEDIS), the most widely used health plan report card in the United States.

• The team used three volume measures: total plan members using mental health services during the study year, the number of members hospitalized for mental health problems, and the number of inpatient mental health days.

• The team used five performance measures. Two measures related to follow-up after a psychiatric hospitalization: the number of patients discharged after hospitalization who had to be rehospitalized after 7 and after 30 days. Three additional measures assessed the appropriateness of antidepressant medication management.

• The results show a significant relationship between low volume and poor performance — and between high volume and good performance. For example:

  • For follow-up after a psychiatric hospitalization: patients in low-volume HMOs were 8% to 21% more likely to have poor follow-up within 7 and within 30 days of hospital discharge.
  • For antidepressant medication management: low-volume HMOs were 3% to 5% more likely to perform poorly.

• In mental health care, as in other areas of medical care, high volume is associated with high-quality care. Further research is needed to better understand exactly how volume affects quality in the mental health arena.

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This fact sheet is based on:

Druss BG, Miller CL, Pincus HA, and Shih S, “The Volume-Quality Relationship of Mental Health: Does Practice Make Perfect?” American Journal of Psychiatry, Vol. 161, No. 12, December 2004, pp. 2282-2286.

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Copyright © 2005 RAND Corporation

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RB-9105 (2005)