Two-fifths of antibiotic prescriptions in the US could have been prescribed inappropriately, say researchers who found poor record keeping may have led to the problem being underestimated.
In a study published in the BMJ, researchers calculated that 13.2% of 990.8 million visits to doctors working outside of hospitals ended in a prescription for an antibiotic.
Of those one in four – or 32 million – was inappropriate, according to the diagnostic code recorded for the patient, but an additional 18% had no indication documented.
The researchers from Oregon State University said the analysis suggests that up to 43% of antibiotics prescribed in the US could be unnecessary.
UK experts said previous research had shown a similarly high proportion of antibiotic prescriptions in Britain do not have a coded diagnosis and stressed the importance of accurate record keeping for understanding prescribing rates.
A more detailed look at the US data showed around 20% of adults aged 18-64 and 22% of the over-65s received antibiotics without a record of why, compared with 8% of patients under 18 years.
Patients with chronic conditions were also more likely to receive an antibiotic without indication (22% vs 14%), the researchers reported.
The researchers said the study ‘demonstrates that indications for antibiotic prescribing are not always adequately documented and this can lead to underestimates of the true burden of unnecessary antibiotic use in ambulatory care settings’.
Writing in the BMJ, Professor Alastair Hay, professor of primary care at the University of Bristol, pointed to UK research showing 36% of antibiotic prescriptions without a coded diagnosis between 2013 and 2015.
He said that having accurate data on prescribing is vital for providing individual feedback to prescribers to help them reflect on their practices and to ensuring that antibiotics are being given out appropriately.
Professor Hay said: ‘Of course individualised feedback is only one of a raft of antimicrobial stewardship strategies needed to improve prescribing, none of which will work in isolation.
‘Others include better infection control, vaccination, and improved diagnostic precision, but the incentive for improving diagnostic coding is to provide information that can be used by clinicians to help them reflect and refine their prescribing behaviour.’
A report from Public Health England in October showed that antibiotic prescribing in general practice fell by 17% between 2014 and 2018 but that antibiotic resistant infections increased over the same period.
It came after a pledge by the Government to cut antibiotic prescribing by a ‘further 15%’ in January as part of a 20-year vision for antimicrobial resistance.