title: Reasons for choice of antibiotic for the empirical treatment of CAP by Canadian infectious disease physicians.
abstract: BACKGROUND
  Previous studies have documented substantial variation in physician prescribing practices for the treatment of community-acquired pneumonia. Much of this variation is the result of empirical treatment, in which physicians must choose antibiotics in the a8bsence of culture and sensitivity data.
  
  
  OBJECTIVE
  To explore the factors that influence antibiotic choice for the empirical treatment of community-acquired pneumonia.
  
  
  METHODS
  Case-based questionnaires were mailed to all 157 members of the Canadian Infectious Disease Society in June 1996. The questionnaires presented three clinical cases and asked respondents which antibiotics they would most likely prescribe. Half the questionnaires were closed-ended, and half were open-ended. In the former, respondents were asked to explain their antibiotic choice by assigning weights to a list of clinical factors. In the latter, respondents were asked to explain their antibiotic choice by providing a short written answer. Respondents were grouped by the class of antibiotics they selected. These groups were then compared with regards to respondent characteristics (age, years of infectious disease experience, adult versus pediatric practice, country of training, province of practice) and rationale for the treatment chosen. Rationale for drug choice was analyzed statistically for the closed-ended questionnaires and qualitatively for the open-ended questionnaires.
  
  
  RESULTS
  A response rate of 84.6% was obtained. For the first clinical case, in which the patient was young and had no underlying illness, the majority of respondents chose a macrolide (74.7%). In the second case, in which the patient was older and had evidence of comorbidity, the most common choice of antibiotic was a penicillin (40.8%). In the third case, in which the patient had intensive care unit-requiring pneumonia, the most popular choice was combination therapy of a third-generation cephalosporin and a macrolide (43.2%). There was decreasing consensus regarding the choice of antibiotics as the complexity of the cases increased. There was evidence that prescribing variation could occasionally be attributed to both respondent characteristics and the use of different decision-making strategies.
  
  
  CONCLUSIONS
  Despite the relative homogeneity of the physicians studied, considerable variation in antibiotic choice was observed. In the first case, this variation was based on the issue of whether the patient had a typical or atypical infection. In the second case, the choice of antibiotic was related to the issue of infection by Haemophilus influenzae, although the results of the Gram stain suggested a pneumococcal infection. In the third case, variance appeared to be based more on the respondent's age and province of practice than on any difference in decision-making strategy.
authors.affiliation: Dalhousie University, Departments of Medicine and Microbiology, Dalhousie University and Victoria General Hospital Site, Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia.
authors.forename: J
authors.initials: J
authors.lastname: Pendergrast
authors.forename: T
authors.initials: T
authors.lastname: Marrie