Antibiotic Timing for CAP: The 4-hour Rule is Coming

Abstract & Commentary

Source: Houck PM, et al. Timing of antibiotic administration and outcomes for Medicare patients hospitalized with community-acquired pneumonia. Arch Intern Med 2004;164:637-644.

Federal agencies and professional societies currently recommend that patients with community-acquired pneumonia (CAP) receive their initial dose of antibiotics within 8 hours of hospital arrival. The Centers for Medicare and Medicaid Services (CMS) conducted this study to explore further associations between timing of initial antibiotic doses and clinical outcomes. Data were collected retrospectively from more than 18,000 patients with CAP who were at least 65 years of age, not immunocompromised, and had not recently received antibiotics or been hospitalized. The investigators studied in-hospital and 30-day mortality, length of stay, and readmission within 30 days.

Study patients were elderly (generally 75-84 years of age), predominantly white, usually had comorbidities, and were most likely to have class IV pneumonia severity index scores. Compared with those who received antibiotics after 4 hours, those receiving antibiotics within 4 hours of hospital arrival had lower in-hospital mortality (6.8% vs 7.4%, odds ratio [OR] 0.85), lower 30-day mortality (11.6% vs 12.7%, OR 0.85), and shorter length of stay (0.4 days). The authors conclude that antibiotic administration within 4 hours of hospital presentation is associated with decreased mortality and length of stay in older patients with CAP. They recommend a 4-hour antibiotic administration goal to improve outcomes in those patients.

Commentary by David J. Karras, MD

Although this study can be criticized on a number of fronts, the immense size of the database and the impact of the sponsor (CMS) render this a powerful study with far-reaching consequences. The study methodology mitigates many of the limitations inherent to the retrospective design. It is debatable, however, whether there is clinical relevance to the improvements seen in patients who received antibiotics earlier. Reductions of mortality by 0.6% and length of stay by 0.4 days, and mortality odds ratios of 0.85 may be statistically meaningful, but arguably the benefit to antibiotic administration within 4 hours is negligible for practical purposes. Obviously, the present condition of many busy EDs makes it impossible to administer antibiotics within 4 hours of hospital presentation due to crowding and other sources of delay.

Nevertheless, CMS has chosen to use CAP outcomes as one of its measures of hospital quality, and it is likely that federal agencies will point to this study as justification for revision of current standards for timing of antibiotic administration. The not-so-hidden agenda behind CMS studies like this one is to drive hospitals to adopt new systems that improve health care delivery, minimize errors, and improve overall patient outcomes. Despite their flaws, these studies and the resulting clinical guidelines do appear to improve the quality of hospital care. It is incumbent upon EDs to develop mechanisms that permit patients with CAP to be evaluated quickly and receive antibiotics within a very short period. It is likely that the quality of our CAP management now will be judged by a much stricter standard, and major changes in ED patient flow will be necessary to meet that goal.

Dr. Karras, Associate Professor of Emergency Medicine, Associate Chair for Academic Affairs, and Research Director, Department of Emergency Medicine, Temple University School of Medicine, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.