The Rational Clinical Examination NOTICE Medicine is an ever-changing science. As new research and clinical experience broaden our knowledge, changes in treatment and drug therapy are required. The authors and the publisher of this work have checked with sources believed to be reli- able in their efforts to provide information that plete and generally in accord with the standards accepted at the time of publication. However, in view of the possi- bility of human error or changes in medical sciences, neither the authors nor the publisher nor any other party who has been involved in the preparation or publica- tion of this work warrants that the information contained herein is in every respect accurate plete, and they disclaim all responsibility for any errors or omissions or for the results obtained from use of the information contained in this work. Read- ers are encouraged to confirm the information contained herein with other sources. For example and in particular, readers are advised to check the product information sheet included in the package of each drug they plan to administer to be certain that the information contained in this work is accurate and that changes have not been made in the mended dose or in the contraindications for administration. This mendation is of particular importance in connection with new or infrequently used drugs. The Rational Clinical Examination Evidence-Based Clinical Diagnosis Editors David L. Simel, MD, MHS Chief, Medicine Service Durham Veterans Affairs Medical Center Professor of Medicine Duke University School of Medicine Durham, North Carolina Drummond Rennie, MD JAMA Chicago, Illinois Philip R. Lee Institute for Health Policy Studies University of California, San Francisco San Francisco, California Editor, Education Guides Sheri A. Keitz, MD, PhD Chief, Medicine Service Miami Veterans Affairs Medical Center Associate Dean for Faculty Diversity and Development Univers