Misuse of antibiotics and asthma medication for acute lower respiratory tract infections in patients with and without asthma in primary care: retrospective cohort study

Talk Code: 
4D.2
Presenter: 
Rachel Denholm
Co-authors: 
Esther van der Werf, Alastair D Hay
Author institutions: 
Centre for Academic Primary Care, University of Bristol; School of Medicine, Taylors University

Problem

Changes to clinical guidance on the use of antibiotics has led to considerable clinical uncertainty in the management of acute lower respiratory tract infections (ALRTIs). Anecdotal evidence suggests antibiotics and step-up asthma medication are overused in asthmatics and non-asthmatics presenting to primary care with ALRTIs. Our aim was to describe the frequency, variation and drivers in antibiotic and step-up asthma medication prescribing for ALRTI in asthmatic and non-asthmatic adults in primary care

Approach

A retrospective cohort analysis of patients aged 18 years and over, diagnosed with an ALRTI in primary care in 2014-15 was conducted using data from the Clinical Practice Research Datalink. Current asthma status, step-up asthma medication and oral antibiotic use within three days of ALRTI infection was determined. Treatment frequency was calculated by asthma status. Mixed-effect regression models were used to explore between practice variation and treatment determinants.

Findings

127,976 ALRTIs were reported among 115,696 patients during the study period, of whom 25,783 (22%) had asthma. Respectively, 79% and 80% of asthmatic and non-asthmatics received antibiotics, and 38% and 14% step-up asthma medication. There were significant differences in between practice prescribing for all treatments, with greatest differences seen for oral steroids (non-asthmatics odds ratio (OR) 90; 95% CI 31 to 368 and asthmatics OR 29; 11 to 124) and step up asthma medication (non-asthmatics OR 20; 11 to 40 and asthmatics OR 10; 5 to 23). Independent predictors of antibiotic prescribing among asthmatics included fewer previous ALRTI presentations (0 vs. 2+: 0.3; 0.2 to 0.4), higher practice antibiotic prescribing (1.5; 1.4 to 1.6) and concurrent step up asthma medication (1.4; 1.3 to 1.5). Other factors included male gender, worse deprivation, and higher prior patient antibiotic prescribing. Predictors were the same in non-asthmatics, with the exception of deprivation, where no association was observed. Independent predictors of step up asthma medication in non-asthmatics included younger age (youngest vs. oldest quartile: 1.5; 1.4 to 1.7), higher prior asthma medication prescribing (7+ vs. 0: 3.2; 2.8 to 3.7) and concurrent antibiotic prescribing (5.7; 5.2 to 6.3). Other factors included female gender, current smoking and higher multimorbidity. Predictors were the same for asthmatics, with the exception of gender and smoking status, where no associations was observed.

Consequences

Findings from the study indicate that antibiotics are over-used for ALRTI, irrespective of asthma status, and step-up asthma medication is over-used in non-asthmatic patients, with between practice variation suggesting considerable clinical uncertainty. Further research is urgently needed to clarify the role of these medications for ALRTI.

Submitted by: 
Rachel Denholm
Funding acknowledgement: 
ADH was funded by NIHR Research Professorship (NIHR-RP-02-12-012)