Introduction
Lower respiratory tract infections (LRTIs) are globally the most common infectious cause of morbidity.1 Despite this prevalence, observed duration of antibiotic treatment for LRTI varies greatly, and there is disagreement between guidelines on the optimal duration.2 Effective first-line treatment for non-pneumonic LRTI in chronic obstructive pulmonary disease (COPD) patients (‘infective exacerbations’) is an area of particular uncertainty.
COPD is a common cause of disability, and estimated to become the third leading cause of death worldwide in 2030.3–5 Exacerbations form a large part of the disease burden and can lead to a cough with discoloured phlegm irrespective of causation. Over £250 million is spent on treating COPD exacerbations annually in the UK, and recurrent exacerbations are associated with increased morbidity and mortality.6
Up to half of all COPD exacerbations are thought to be caused by bacteria, the remainder by viruses or environmental irritants.7–10 The most common pathogens are Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae.6 Initial studies suggested that the administration of antibiotics was associated with a lower risk of symptom persistence.11 However, a Cochrane review concluded that a statistically significant improvement in treatment failure rate was only seen in severe exacerbations, with more adverse events in the antibiotic group.7 Hence, the European Respiratory Society/American Thoracic Society and international guidelines advise, based on moderate evidence, the prescription of antibiotics for ambulatory patients ‘if clinically indicated’.12 13 However, our understanding of the success of real-life prescribing practices is limited.
The risk of treatment failure without antibiotics needs to be balanced with antimicrobial resistance, contributed to by inappropriate and non-evidence based prescribing, and adverse drug effects, including Clostridium difficile infection.14–16 Primary care is an optimal environment to improve antibiotic use since 74% of all UK antibiotics are prescribed here and around three-quarters of patients presenting in primary care with an acute COPD exacerbation receive antibiotics.17–19 Moreover, a European-wide COPD audit of hospitalised patients demonstrated that antibiotics were more likely to be continued during admissions and after discharge if they had already been received in primary care.20
Guidelines on antibiotics for COPD exacerbations are not specific and based only on moderate evidence. The National Institute of Health and Care Excellence guidelines for the study period suggest using an aminopenicillin, macrolide or tetracycline but give no indication on duration.21 The Global Initiative for Chronic Obstructive Lung Disease advises 5–7 days duration but no antibiotic class.13 A recent meta-analysis presented dirithromycin, ofloxacin and ciprofloxacin as having the best cure and side-effect profiles, yet these are not used routinely in clinical practice.22
In this study, we characterised patterns of antibiotic prescribing for COPD exacerbations via a retrospective observational analysis of primary care data from 2010 to 2015. We explored the factors associated with the risk of further antibiotic prescription, which may form the basis for future comparative interventional studies, such as clinical trials comparing different antibiotic durations, or first-line drugs in specific patient groups.