Pulmonary Pharmacology & Therapeutics (2001) 14, 149–155 doi:10.1006/pupt.2001.0289, available online at http://www.idealibrary.com.on PULMONARY PHARMACOLOGY & THERAPEUTICS Antibiotic Treatment and Baseline Severity of Disease in Acute Exacerbations of Chronic Bronchitis: A Re-evaluation of Previously Published Data of a Placebo-controlled Randomized Study Luigi Allegra, Francesco Blasi, Barbara de Bernardi*, Roberto Cosentini,† Paolo Tarsia† Institute of Respiratory Diseases, and †Department of Emergency Medicine, University of Milan, IRCCS Ospedale Maggiore Milano, *Smith-Kline-Beecham, Milan, Italy SUMMARY: The study was designed to extend retrospectively the analysis of a previously reported study on chronic bronchitis patients with acute exacerbations treated with amoxicillin–clavulanic acid or matched placebo. We retrospectively re-clustered patients on the basis of severity of baseline lung function: Cluster 1 (104 patients) mean screening FEV 1 32.67±6.83 (SD); Cluster 2 (109 patients) mean screening FEV 1 54.12±5.56; Cluster 3 (122 patients) mean screening FEV 1 71.54±5.51. The success rate in the antibiotic group was significantly greater compared to the placebo group (P<0.001). When clinical improvement was analysed on the basis of patient re- clustering, 31.4% of Cluster 1 (severe COPD) patients treated with amoxicillin/clavulanate showed clinical improvement, whereas success was recorded in 58.8%. Conversely, 13.2% of Cluster 1 patients receiving placebo improved and 17% successfully recovered (P<0.001). Mild and moderate COPD patients (Clusters 2 and 3) were grouped together. In these two groups, 31.2% and 53.6% of patients receiving antibiotic treatment showed improvement or recovery, respectively, compared to 29.2% improvements and 30.2% successful recoveries among placebo-treated patients (P<0.001). In placebo-treated patients the improvement/success vs. failure rate was significantly different in Cluster 1 patients compared to Cluster 2+3 subjects (P<0.01,  2 test). The differences in final FEV 1 values in the treatment group and placebo group were significantly different (P <0.01) in favour of the active treatment group. Among more severe patients (Cluster 1), the comparison between screening and follow up FEV 1 values showed an improvement following antibiotic treatment and worsening after placebo (P<0.01). In Clusters 2 and 3 the difference between screening and follow up FEV 1 values was not significant for both treatment groups. Our patients with severe functional impairment and higher number of exacerbations per year are those who derive the greatest benefit from antibiotic treatment.  2001 Academic Press KEY WORDS: COPD, Exacerbations, Lung function, Antibiotics. of antibiotic prescription among respiratory in- INTRODUCTION fections. It is still uncertain whether each new ex- acerbation may deteriorate the natural history of Chronic obstructive pulmonary disease (COPD) is chronic bronchitis. Undoubtedly, every episode in- present in 20% of the population in the United States. 1 duces a temporary worsening in lung function and Exacerbations of chronic bronchitis are a common may therefore pose a threat of respiratory failure or occurrence in clinical practice, and are a leading cause death in more severely obstructed patients. Exacerbations are usually defined as an increase in cough, a change in the colour or quantity of sputum, Author for correspondence: Francesco Blasi, MD, PhD, Instituto di Tisiologia e Malattie dell’Apparato Respiratorio, Universita ` or worsening dyspnea. 2 The role of bacterial infections degli Studi di Milano, Pad. Litta, IRCCS Ospedale Maggiore di and the efficacy of antimicrobial therapy in acute Milano. via F. Sforza, 35 I-20122 Milano-ITALY. Fax: +39 02 55190332. E-mail: francesco.blasi@unimi.it exacerbations of chronic bronchitis (AECB) is still 1094–5539/01/020149+07 $35.00/0  2001 Academic Press 149