Guidelines for the management of community-acquired pneumonia (CAP) have been published by several medical organizations, including the British Thoracic Society, the American Thoracic Society, and the Infectious Diseases Society of America (IDSA). Do these guidelines help improve survival rates? Yes, according to a study that focused on adherence to the IDSA guidelines and outcomes for patients with severe CAP. This study also underscores the importance of providing adequate coverage for Pseudomonas aeruginosa in patients with risk factors such as chronic obstructive pulmonary disease (COPD), malignancy, or recent antibiotic treatment. Bodi and coworkers prospectively studied 529 adults who had severe CAP and were admitted to an ICU. The rate of adherence to the IDSA guidelines was 57.8%. The mortality rate was significantly higher among patients for whom the IDSA guidelines were not followed--33.2% versus 24.2% among those for whom the guidelines were followed. Independent risk factors for death (that were identified on admission) included patients' age, APACHE II score, immunocompromised state, and nonadherence to guidelines (Table). The study also found that the antimicrobial treatment at admission was inadequate in 75% of the 20 patients who had CAP caused by P aeruginosa; this included 8 of the 15 patients for whom the guidelines were followed. Risk factors for P aeruginosa pneumonia included COPD, malignancy, previous antibiotic exposure, and radiographic evidence of rapid spread of disease. In an editorial, Marrie suggests that the findings reported by Bodi and associates may be an example of the "halo effect"--in this case, following the practice guidelines may have had benefits that extended beyond the effects of the specific recommendations. In fact, adhering to the guidelines probably had effects that were independent of the antibiotics selected. Marrie concludes that if there really is a halo effect, the data should soon indicate that the mortality rates associated with CAP are declining.
