Safety of reduced antibiotic prescribing for self limiting respiratory tract infections in primary care: cohort study using electronic health records

Abstract

Objective: To determine whether the incidence of pneumonia, peritonsillar abscess, mastoiditis, empyema, meningitis, intracranial abscess, and Lemierre's syndrome is higher in general practices that prescribe fewer antibiotics for self limiting respiratory tract infections (RTIs).

Design: Cohort study.

Setting: 610 UK general practices from the UK Clinical Practice Research Datalink.

Participants: Registered patients with 45.5 million person years of follow-up from 2005 to 2014.

Exposures: Standardised proportion of RTI consultations with antibiotics prescribed for each general practice, and rate of antibiotic prescriptions for RTIs per 1000 registered patients.

Main outcome measures: Incidence of pneumonia, peritonsillar abscess, mastoiditis, empyema, meningitis, intracranial abscess, and Lemierre's syndrome, adjusting for age group, sex, region, deprivation fifth, RTI consultation rate, and general practice.

Results: From 2005 to 2014 the proportion of RTI consultations with antibiotics prescribed decreased from 53.9% to 50.5% in men and from 54.5% to 51.5% in women. From 2005 to 2014, new episodes of meningitis, mastoiditis, and peritonsillar abscess decreased annually by 5.3%, 4.6%, and 1.0%, respectively, whereas new episodes of pneumonia increased by 0.4%. Age and sex standardised incidences for pneumonia and peritonsillar abscess were higher for practices in the lowest fourth of antibiotic prescribing compared with the highest fourth. The adjusted relative risk increases for a 10% reduction in antibiotic prescribing were 12.8% (95% confidence interval 7.8% to 17.5%, P<0.001) for pneumonia and 9.9% (5.6% to 14.0%, P<0.001) for peritonsillar abscess. If a general practice with an average list size of 7000 patients reduces the proportion of RTI consultations with antibiotics prescribed by 10%, then it might observe 1.1 (95% confidence interval 0.6 to 1.5) more cases of pneumonia each year and 0.9 (0.5 to 1.3) more cases of peritonsillar abscess each decade. Mastoiditis, empyema, meningitis, intracranial abscess, and Lemierre's syndrome were similar in frequency at low prescribing and high prescribing practices.

Conclusions: General practices that adopt a policy to reduce antibiotic prescribing for RTIs might expect a slight increase in the incidence of treatable pneumonia and peritonsillar abscess. No increase is likely in mastoiditis, empyema, bacterial meningitis, intracranial abscess, or Lemierre's syndrome. Even a substantial reduction in antibiotic prescribing was predicted to be associated with only a small increase in numbers of cases observed overall, but caution might be required in subgroups at higher risk of pneumonia.

Fig 1 Age standardised consultation rate for self limiting respiratory tract infections (RTIs), antibiotic prescribing rate for RTIs, and proportion of RTI consultations with antibiotics prescribed in 610 general practices contributing to the UK Clinical Practice Research Datalink. Red open circles represent females; blue filled circles represent males. Lines fitted by least squares

Fig 2 Incidence of infective complications in 610 general practices contributing to the UK Clinical Practice Research Datalink. Red open circles represent females; blue filled circles represent males. Lines fitted by least squares

Fig 3 Association of incidence of infective complications with fourth of consultation rate for self limiting respiratory tract infections (RTIs). Rates are number of incident events per 100 000 person years. Incidence rate ratios (IRRs) were adjusted for sex, age group, region, deprivation fifth, and clustering by general practice

Fig 4 Association of incidence of infective complications with fourth of antibiotic prescribing proportion. Incidence rate ratios (IRRs) were adjusted for consultation rate for respiratory tract infections, sex, age group, region, deprivation fifth, and clustering by general practice

Fig 5 Association of incidence of infective complications with fourth of antibiotic prescribing rate. Incidence rate ratios (IRRs) were adjusted for consultation rate for respiratory tract infections, sex, age group, region, deprivation fifth, and clustering by general practice