Up to 50% of patients with giant cell arteritis (GCA) have visual symptoms early in the disease course, in most cases due to anterior ischemic optic neuropathy (AION). 1 The vision loss from AION in GCA is often devastating, with the initial visual acuity being 20/200 or worse in more than 50% of patients. 1,2 There is often, but not always, pallid optic disc edema and there is rarely a These guides grew out of a collaboration between McMaster University and JAMA when a series of articles was published, between 1993 and 2000, advising clinicians on how to read medical literature. The Evidence-Based Medicine Working Group then aggregated these articles into the first edition of Users' Guide to the Medical Literature. In the Users' Guides to the Medical Literature section edi-tor: Drummond Rennie, MD, Deputy Editor (West), JAMA. Downloaded from jama.ama-assn.org at Johns Hopkins University on March 18, 2011. Table 1.—Users' Guides for How to Use Review Articles Are the results ofthe study valid? Users' Guides to the Medical Literature From the Journal of the American Medical Association (JAMA) Initially compiled by Tom Emmett, MD, MLS; Updated by Holly Ann Burt, MLIS, AHIP . A series introducing strategies for efficiently searching the medical literature. Introduction: Guyatt GH, Rennie D. Users' guides to the medical literature. Importance Every year, the US Food and Drug Administration (FDA) inspects several hundred clinical sites performing biomedical research on human participants and occasionally finds evidence of substantial departures from good clinical practice and research misconduct. However, the FDA has no systematic method of communicating these findings to the scientific community, leaving open the Guyatt GH, Sackett DL, Cook DJ, Guyatt G, Bass E, Brill Edwards P et al. Users' Guides to the Medical Literature: II. How to Use an Article About Therapy or Prevention B. What Were the Results and Will They Help Me in Caring for My Patients? JAMA