Defining the appropriateness and inappropriateness of antibiotic prescribing in primary care

Abstract

Objectives: To assess the appropriateness of prescribing systemic antibiotics for different clinical conditions in primary care, and to quantify 'ideal' antibiotic prescribing proportions in conditions for which antibiotic treatment is sometimes but not always indicated.

Methods: Prescribing guidelines were consulted to define the appropriateness of antibiotic therapy for the conditions that resulted in antibiotic prescriptions between 2013 and 2015 in The Health Improvement Network (THIN) primary care database. The opinions of subject experts were then formally elicited to quantify ideal antibiotic prescribing proportions for 10 common conditions.

Results: Of the antibiotic prescriptions in THIN, 52.5% were for conditions that could be assessed using prescribing guidelines. Among these, the vast majority of prescriptions (91.4%) were for conditions where antibiotic appropriateness is conditional on patient-specific indicators. Experts estimated low ideal prescribing proportions in acute, non-comorbid presentations of many of these conditions, such as cough (10% of patients), rhinosinusitis (11%), bronchitis (13%) and sore throat (13%). Conversely, antibiotics were believed to be appropriate in 75% of non-pregnant women with non-recurrent urinary tract infection. In impetigo and acute exacerbation of chronic obstructive pulmonary disease, experts clustered into distinct groups that believed in either high or low prescribing.

Conclusions: In English primary care, most antibiotics are prescribed for conditions that only sometimes require antibiotic treatment, depending on patient-specific indicators. Experts estimated low ideal prescribing proportions in many of these conditions. Incomplete prescribing guidelines and disagreement about prescribing in some conditions highlight further research needs.

Figure 1.

Appropriateness of antibiotic prescriptions according to guidelines. Approximately half (52.5%) of all antibiotic prescriptions in THIN were for conditions that could be assessed using prescribing guidelines. The vast majority of these (48.0% of all prescriptions) were for conditions where antibiotics are sometimes but not always appropriate, whereas a small proportion were for conditions where antibiotics are always (3.7%) or never (0.8%) appropriate. Appropriateness could not be assessed in 47.5% of prescriptions due to poor/ambiguous diagnostic coding (36.7%) and unclear/missing guidelines (10.8%).

Figure 2.

A pooled histogram of experts’ estimates of the percentage of patients that should be prescribed oral antibiotics when presenting to primary care with AE COPD. The component β distributions (green and purple lines) of the mixture distribution (orange line) indicate that experts are divided into two groups: those who believe in high versus low prescribing. Dashed coloured lines represent the medians of each distribution.

Figure 3.

Individual and pooled estimates of ideal prescribing proportions. Black dots show each expert’s median estimate for each condition, and coloured dots and bars show median and IQRs for pooled estimates. In impetigo and AE COPD, additional coloured dots and bars to the left of the individual estimates show the median and IQRs of the component distributions that comprise their respective mixture distributions.