Incidence of Clostridioides difficile infection (CDI) related to antibiotic prescribing by GP surgeries in Wales

Background: Clostridioides difficile infection (CDI) is a healthcare-acquired infection (HAI) causing significant morbidity and mortality. Welsh CDI rates are high in comparison to England and Scotland.
Objectives: This retrospective ecological study used aggregated disease surveillance data to understand the impact of total, and high-risk, Welsh general practitioner (GP) antibiotic prescribing of total, and stratified inpatient/ non-inpatient, CDI incidence.
Methods: All cases of confirmed CDI, during financial years 2014/15 -2017/18, were linked to aggregated rates of antibiotic prescribing in their GP surgery and classified as ‘inpatient’, ‘non-inpatient’ or ‘unknown’ by Public Health Wales. Multivariable negative-binomial regression models, comparing CDI incidence with antibiotic prescribing rates, were adjusted for potential confounders: location; age; social deprivation; co-morbidities (estimated from prevalence of key health indicators) and proton pump inhibitor (PPI) prescription rates.
Results: There were 4613 confirmed CDI cases, with an incidence of 1.44/1000 (95% CI, 1.40-1.48) registered patients. Unadjusted analysis showed an increased risk of total CDI incidence associated with higher total antibiotic prescribing (RR= 1.338, 95% CI 1.170 -1.529, per 1000 items per 1000 STAR-PU) and that high-risk antibiotic classes were positively associated with total CDI incidence. Location, age over 64 (%) and diabetes (%) were associated with increased risk of CDI. After adjusting for confounders, prescribing of clindamycin showed a positive association with total CDI incidence (RR=1.079, 95% CI 1.001 – 1.162 log items per 1000 registered patients).
Conclusions: An increased risk of CDI is demonstrated at a primary care practice population level reflecting their antibiotic prescribing rates, particularly clindamycin, and population demographics.