Delaying antibiotics in upper respiratory tract infection could increase risk of hospital admission, study suggests

Delayed antibiotic prescribing is associated with an increase in the risk of infection-related hospital admissions and repeat antibiotic prescribing in patients with upper respiratory tract infection (URTI), a study in Clinical Infectious Diseases has suggested.

The researchers used English and Welsh data from two population-based cohort studies, containing electronic health records from primary care linked to hospital admission records.

Patients identified as having a URTI, who were prescribed amoxicillin, clarithromycin, doxycycline, erythromycin or phenoxymethylpenicillin, were split according to delayed and immediate prescribing relative to URTI diagnosis.

Of the 1.82 million patients included in the study, 91.7% were prescribed an antibiotic when they were diagnosed with a URTI, which was defined as ‘immediate’, and 8.3% were prescribed an antibiotic between 1 and 30 days after being diagnosed with a URTI. This was defined as ‘delayed’.

Overall, the researchers found that delayed antibiotic prescribing was associated with a 52% increased risk of infection-related hospital admissions (adjusted hazard ratio of 1.52, 95% confidence interval 1.43-1.62).

The number of individuals that would need to be exposed to a delayed antibiotic prescription in order to cause harm in one additional person — known as the ‘number needed to harm’ — was found to vary considerably between different patient groups. However, the researchers found that the probability of patients having a delayed prescription was not related to their risk of being admitted to hospital for infection-related complications.

According to the researchers, the UK URTI guideline, published by the National Institute for Health and Care Excellence (NICE), states that the decision between immediate or delayed/no antibiotic should be based on a clinical assessment of infection severity.

“The present study found that delayed antibiotic prescribing was not targeted to patients with lower risks of complications,” they said.

“This indicates that further research is needed to optimise the targeting of delayed antibiotic prescribing in order to provide more specific guidance when and when not to use this strategy.” 

However, Stephen Hughes, consultant antimicrobial pharmacist at Chelsea and Westminster NHS Foundation Trust, said that a major limitation identified in the study was the definition of a delayed prescription.

“It is not as defined in NICE or PHE [Public Health England] guidelines, where a prescription is prescribed and either future dated or the patient is advised not to take it unless symptoms worsen.

Hughes said he thought that prescriptions classed as ‘delayed’ were not delayed at all and could have included a subset of patients who had a URTI diagnosed before requiring an antibiotic in the following 1–30 days for potentially “any infection”. 

“[The researchers’] methodology is defined as any prescription for an antibiotic — they list 4–5 — that is prescribed on a second consult within 1–30 days after an initial consult which diagnosed the URTI. [So] they could have an antibiotic for other infections and still be defined as ‘delayed’.

“This is a major limitation and I think will skew the results accordingly; a true ‘delayed prescription’, which is issued during the consult, [with the] patient advised not to immediately take [it], will not be included in the ‘delayed’ arm, but rather misclassified as ‘immediate’.”

“These patients, not surprisingly, have a higher risk of admission,” he added.