Antibiotic use in the care home setting: a retrospective cohort study analysing routine data

BACKGROUND: Point prevalence studies in care homes show a high use of antibiotics, especially to treat urinary tract infections (UTI). There is a lack of large studies presenting annual antibiotic prescription data in care homes compared to those not in care homes. This study aimed to describe the pattern of antibiotic prescribing in those 75 years and over, with a focus on UTI. METHODS: In this retrospective longitudinal cohort study we used the Hampshire Health Record (HHR) containing routine data from general practices in Hampshire area, UK covering 1.24 million residents. Data were extracted throughout 2011 from the Hampshire Health Record on age, gender, care home status, antibiotic prescriptions, urinary catheters and comorbidity. Prescription pattern expressed as rate per 100 people. Nursing home residence defined by postcode. Logistic regression was used to assess independent risk of one or more antibiotic prescriptions in care home residents adjusting for age, sex and comorbidity, separately by catheter use. RESULTS: 102,020 of 1,244,313 residents in the Hampshire Health Record (8.2 %) were aged ≥75 years of whom 7481 (7.3 %) were resident in care home settings. The annual antibiotic prescriptions increased from 53/100 inhabitants among those <75 years, to 142/100 among those ≥75 years not in a care home and to 199/100 among those ≥75 years in a care home. Care home residents with urinary catheters (4.4 %) had even higher use at 440/100 versus 188/100 if no catheter. UTI antibiotics showed a similar but more rapidly increasing pattern. For those in care homes without a urinary catheter, the odds ratio was 2.2 (2.1–2.3) higher for prescriptions of UTI antibiotics compared to those not in care homes after adjusting for age, gender and comorbidity. For those with a urinary catheter the odds ratio was 1.4 (1.1–1.8) for UTI antibiotics compared to those not in care homes. For all antibiotics the odds ratio was 1.2 (1.2–1.3). CONCLUSIONS: Residence in a care home setting is associated with high antibiotic consumption; this is especially evident for UTI antibiotics where the odds of prescription is doubled.