The Halo Effect of Adherence to Guidelines Extends to Patients with Severe Community-Acquired Pneumonia Requiring Admission to an Intensive Care Unit

The community-acquired pneumonia (CAP) guideline writing industry started with a group of physicians who met in Halifax, Nova Scotia, on 22 and 23 No-vember 1991 to write a guideline for the management of CAP. This led to an expanded group of " experts " who met in Boston, Massachusetts, in October 1992 for the same purpose, under the auspices of the American Thoracic Society. These 2 meetings resulted in the Canadian Tho-racic Society [1] and American Thoracic Society [2] CAP guidelines. Subsequently, the Infectious Diseases Society of America (IDSA) issued its own guidelines [3], and then these 3 organizations revised or updated their guidelines [3–6]. Along the way, the Centers for Disease Control and Prevention issued guidelines designed to promote optimal use of antibiotics in the management of CAP [7], and guidelines for the management of CAP have been issued by many countries, of which only a couple are cited here [8, 9]. For the most part, these guidelines focus on the choice of empirical antibiotic therapy according to the site of care: home, hospital ward, or intensive care unit (ICU) [1–6]. Advice is also provided for diagnostic evaluation [5, 6], and criteria are given for admission to the hospital [4– 6] and to the ICU [5, 6]. There are now a number of studies that have examined the effect of these guidelines on patient care. Institutions have made some modifications of the guidelines and have incorporated several aspects of their recommendations into the treatment of pneumonia, such as use of an admission guide, administration of antibiotic therapy according to the type of health care site, evaluation of time to receipt of antibiotics, and assessment of clinical stability as a guide to discharge into a critical pathway for the treatment of pneumonia. The design of the studies [10–15] that have examined the effect of these guidelines have differed and include time series [10, 15]; comparisons of conditions before and after institution of the guidelines, with concurrent controls [11, 14]; and cluster randomization [12, 13]. Three studies showed a decreased length of hospital stay following the intervention [10, 13, 14], 1 study [11] showed a decrease in mortality, and 1 study [15] showed no effect on the length of hospital stay, which was the only variable measured in that study. However, 3 more-recent studies suggest that there is an added benefit to following guidelines, which has been called the " halo …