Prepared for:

Agency for Healthcare Research and Quality

Department of Health and Human Services

U.S. Public Health Service

2101 East Jefferson Street

Rockville, MD 20852

www.ahrq.gov

Contract No. 290-97-0001

Prepared by:

Southern California Evidence-Based Practice Center/RAND

Mary Hardy

Ian Coulter

Swamy Venuturupalli

Elizabeth A. Roth

Joya Favreau

Sally C. Morton

Paul Shekelle

AHRQ Publication No. 01-E040

September 2001

ISBN: 1-58763-068-0

ISSN: 1530-4396

Southern California Evidence-based Practice Center/RAND

Director Paul Shekelle, M.D., Ph.D.

Co-Director and Senior Statistician Sally C. Morton, Ph.D

Task Order Director Mary Hardy, M.D.

Task Order Co-Director Ian Coulter, Ph.D.

Expert Reviewers Mary Hardy, M.D.

Swamy Venuturupalli, M.D.

Senior Programmer/Analyst Elizabeth A. Roth, M.A.

Reference Librarian Roberta Shanman, M.L.S.

Editor Elizabeth Maggio, B.A.

Research Associate Joya Favreau, M.D.

Task Order Coordinators Barbara Genovese, M.A.

Lara Jungvig, B.A.

Staff Assistants Louis R. Ramirez, B.A.

Leigh Rohr

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. Endorsement by the Agency for Healthcare Research and Qaulity (AHRQ) or the U.S. Department of Health and Human Services (DHHS) of such derivative products may not be stated or implied.

AHRQ is the lead Federal agancy charged with supporting research designed to improve the quality of health care, reduce its cost, address patient safety and medical errors, and broaden access to essential services. AHRQ sponsors and conducts research that provides evidence-based information on on health care outcomes; quality; and cost, use, and access. The information helps health care decisionmakerspatients and clinicians, health system leaders, and policymakersmake more informed decisions and improve the quality of health care services.