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Original research
Serious bacterial infections and antibiotic prescribing in primary care: cohort study using electronic health records in the UK
  1. Martin C Gulliford1,2,
  2. Xiaohui Sun1,
  3. Judith Charlton1,
  4. Joanne R Winter1,
  5. Catey Bunce1,2,
  6. Olga Boiko1,
  7. Robin Fox3,
  8. Paul Little4,
  9. Michael Moore4,
  10. Alastair D Hay5,
  11. Mark Ashworth1
  12. And SafeAB Research Group
    1. 1School of Population Health and Environmental Sciences, King's College London, London, UK
    2. 2NIHR Biomedical Research Centre at Guy’s and St Thomas’ Hospitals London, GreatMaze Pond, London, UK
    3. 3The Health Centre, Coker Close, Bicester, UK
    4. 4Primary Care Research Group, University of Southampton, Southampton, UK
    5. 5Centre for Academic Primary Care, Bristol Medical School, Population Health Sciences, University of Bristol, Bristol, UK
    1. Correspondence to Professor Martin C Gulliford; martin.gulliford{at}


    Objective This study evaluated whether serious bacterial infections are more frequent at family practices with lower antibiotic prescribing rates.

    Design Cohort study.

    Setting 706 UK family practices in the Clinical Practice Research Datalink from 2002 to 2017.

    Participants 10.1 million registered patients with 69.3 million patient-years’ follow-up.

    Exposures All antibiotic prescriptions, subgroups of acute and repeat antibiotic prescriptions, and proportion of antibiotic prescriptions associated with specific-coded indications.

    Main outcome measures First episodes of serious bacterial infections. Poisson models were fitted adjusting for age group, gender, comorbidity, deprivation, region and calendar year, with random intercepts representing family practice-specific estimates.

    Results The age-standardised antibiotic prescribing rate per 1000 patient-years increased from 2002 (male 423; female 621) to 2012 (male 530; female 842) before declining to 2017 (male 449; female 753). The median family practice had an antibiotic prescribing rate of 648 per 1000 patient-years with 95% range for different practices of 430–1038 antibiotic prescriptions per 1000 patient-years. Specific coded indications were recorded for 58% of antibiotic prescriptions at the median family practice, the 95% range at different family practices was from 10% to 75%. There were 139 759 first episodes of serious bacterial infection. After adjusting for covariates and the proportion of coded consultations, there was no evidence that serious bacterial infections were lower at family practices with higher total antibiotic prescribing. The adjusted rate ratio for 20% higher total antibiotic prescribing was 1.03, (95% CI 1.00 to 1.06, p=0.074).

    Conclusions We did not find population-level evidence that family practices with lower total antibiotic prescribing might have more frequent occurrence of serious bacterial infections overall. Improving the recording of infection episodes has potential to inform better antimicrobial stewardship in primary care.

    • primary care
    • respiratory infections
    • urinary tract infections
    • diagnostic microbiology

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    • Collaborators The SafeABStudy Group also includes Dr Caroline Burgess, Dr Vasa Curcin and Dr James Shearer.

    • Contributors MCG wrote the study protocol with advice from CB, RF, MA, PL, MM and ADH. XS developed and piloted code sets and analyses for antibiotic prescribing; RF, PL, MM, ADH and MA reviewed case definitions. JC programmed analyses and JRW advised. MCG completed data analyses and drafted the paper with advice from CB, RF, PL, MM, ADH and MA. OB coordinated PPI input. All authors reviewed and contributed to the final draft. MCG is guarantor.

    • Funding The study is funded by the National Institute for Health Research (NIHR) Health Services and Delivery Programme (16/116/46). MCG was supported by the NIHR Biomedical Research Centre at Guy’s and St Thomas’ Hospitals.

    • Disclaimer The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, or the Department of Health. The funder of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The authors had full access to all the data in the study and all authors shared final responsibility for the decision to submit for publication.

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Ethics approval The protocol was approved by the CPRD Independent Scientific Advisory Committee (ISAC protocol 18–041R).

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement Data are available on reasonable request. Requests for access to data from the study should be addressed to All proposals requesting data access will need to specify planned uses with approval of the study team and CPRD before data release.

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