The relation between purulent manifestations and antibiotic treatment of upper respiratory tract infections

OBJECTIVE: To describe the clinical features of patients diagnosed with upper respiratory tract infections (URIs), and determine: which clinical features are associated with antibiotic use. DESIGN:Prospective cohort study. SETTING: Three ambulatory care practices at a group-model HMO in the Denver metropolitan area. PATIENTS:Adults (aged 18 years or older) seeking care for acute respiratory illnesses. MEASUREMENTS: Clinical features were documented on standardized encounter forms. Clinician type, secondary diagnoses, and antibiotic treatment were extracted from administrative databases. Results are presented as adjusted odds ratios (ORs) with 95% confidence intervals (CIs). MAIN RESULTS: Antibiotics were prescribed to 33% (95% CI 28%, 38%) of patients diagnosed with URI, after excluding patients with coexisting antibiotic-responsive conditions (e.g., sinusitis, pharyngitis) or a history of cardiopulmonary disease. Multivariate logistic regression analysis identified tobacco use (OR 2.8; 95% CI 1.5, 5.1), history of purulent nasal discharge (OR 2.0; 95% CI 1.1, 3.6) or green phlegm (OR 4.8; 95% CI 2.1, 11.1), and examination findings of purulent nasal discharge (OR 5.2; 95% CI 2.4, 11.2) or tonsillar exudate (OR 3.7; 95% CI 1.1, 12.1) to be independently associated with antibiotic use. The majority of patients treated with antibiotics (82%) had at least one of these factors present. CONCLUSIONS: Antibiotic treatment of URIs is most common when purulent manifestations are present. Efforts to reduce antibiotic treatment of URIs should educate clinicians about the limited value of purulent manifestations in predicting antibiotic-responsive disease.