Predictors of treatment with antibiotics and systemic corticosteroids for acute exacerbations of asthma and chronic obstructive pulmonary disease in primary care

Antibiotic and oral corticosteroid prescribing rate in patients suffering from acute exacerbations of chronic obstructive pulmonary disease (COPD) or asthma in general practice are only sparsely described. Our aim was to identify predictors for such prescribing when results from CRP testing, spirometry, and pulse oximetry are available.

Patients aged 40 years or more diagnosed with asthma, COPD or both, the previous five years from seven general practice offices in Norway, were invited to a baseline examination and asked to visit their GPs during exacerbations the following 12 months. At all visits, symptoms, chest findings, and results from spirometry, pulse oximetry and CRP testing were registered.

Out of the 376 who took part in baseline examination, 95 patients with an exacerbation were included in the analysis. Based on the diagnosis made by GPs, 46 patients (48.4%) were only registered with asthma, and 49 (51.6%) with COPD (or both diagnosis). 11 patients had taken antibiotics and 16 had taken systemic corticosteroids prior to their visit to their GPs. After excluding those already treated, antibiotics were prescribed in 34.9% and systemic corticosteroids in 42.5% of patients diagnosed with COPD compared to 14.6% and 30.8% respectively in patients only diagnosed with asthma (P = 0.02, P = 0.2). In the COPD group, antibiotic prescribing was not significantly associated with purulence or other respiratory symptoms, but increased phlegm was a significant predictor of antibiotic prescribing in the whole sample (P = 0.04). Prolonged expiration, wheezes and diminished breath sounds also predicted the prescribing of both antibiotics and systemic corticosteroids in the whole sample with P values < 0.01. The prescribing rate of antibiotics and systemic corticosteroids also increased with increasing CRP value (P = 0.001 and P = 0.01, respectively) and with decreasing oxygen saturation (P = 0.01 and P = 0.003, respectively). FEV₁/FVC < 0.7 at baseline was as significant predictor in patients with COPD and in the whole sample of patients regarding treatment with antibiotics (P = 0.004 and P = 0.001, respectively) and treatment with systemic corticosteroids (P = 0.004 and P = 0.001, respectively).

Chest findings, raised CRP value and decreased oxygen saturation were stronger predictors of prescribing of antibiotics and systemic corticosteroids than were respiratory symptoms. Further evaluation of the importance of these findings to guide treatment of asthma and COPD exacerbations is warranted.