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Analysis of Means Used to Compare Providers' Referral Patterns

Homa, Karen PhD

doi: 10.1097/

Objectives The objective of this study was to demonstrate through a case study how an analysis of means (ANOM) chart can be used to compare groups and to advocate the usefulness of this method in improvement work.

Methods The ANOM technique was used to compare referral rates among providers at the Dartmouth-Hitchcock Medical Center's Spine Center. The purpose was to see whether there were any differences across providers in referral rates to Behavioral Medicine services for patients who scored low on their mental health score and whether referral rates were any different among the patient characteristics. ANOM charts were also used to determine whether patient characteristics were different among the providers.

Results Six of the 17 providers had significantly different referral rates compared to the overall referral rate of 38%. Seven patients' characteristics had a significantly different referral rate compared to the system's rate. The additional ANOM charts used to compare providers relative to specific patient characteristics demonstrated several special causes and revealed characteristic referral patterns for some of the providers analyzed.

Conclusion The ANOM chart may be underutilized in health care improvement work. The ANOM procedure of analyzing patient characteristics to determine differences among providers could be explored in other patient populations and settings.

Dartmouth-Hitchcock Leadership Preventive Medicine Residency Program, Mary Hitchcock Memorial Hospital, Lebanon, New Hampshire.

Corresponding Author: Karen Homa, PhD, 30 Lafayette St, Lebanon, NH 03766 (

The author is extremely grateful to the dedicated leaders, health care providers, and staff in the Spine Center at Dartmouth-Hitchcock for their support in this research endeavor. In addition, the author thanks Mark Splaine, MD, MS, for introducing her to ANOM and Tina Foster, MD, MPH, MS, for her careful review and insightful comments on the manuscript.

©2007Lippincott Williams & Wilkins, Inc.