Antibiotic prescribing and associated diarrhoea: a prospective cohort study of care home residents.

Background: the risk factors for and frequency of antibiotic prescription and antibiotic-associated diarrhoea (AAD) among care home residents are unknown.
Aim: to prospectively study frequency and risks for antibiotic prescribing and AAD for care home residents.
Design and Setting: a 12-month prospective cohort study in care homes across South Wales.
Method: antibiotic prescriptions and the development of AAD were recorded on case report forms. We defined AAD as three or more loose stools in a 24-h period occurring within 8 weeks of exposure to an antibiotic.
Results: we recruited 279 residents from 10 care homes. The incidence of antibiotic prescriptions was 2.16 prescriptions per resident year (95% CI: 1.90-2.46). Antibiotics were less likely to be prescribed to residents from dual-registered homes (OR compared with nursing homes: 0.38, 95% CI: 0.18-0.79). For those who were prescribed antibiotics, the incidence of AAD was 0.57 episodes per resident year (95% CI: 0.41-0.81 episodes). AAD was more likely in residents who were prescribed co-amoxiclav (hazards ratio, HR = 2.08, 95% confidence interval, CI: 1.18-3.66) or routinely used incontinence pads (HR = 2.54, 95% CI: 1.26-5.13) and less likely in residents from residential homes (HR compared with nursing homes: 0.14, 95% CI: 0.06-0.32).
Conclusion: residents of care homes, particularly of nursing homes, are frequently prescribed antibiotics and often experience diarrhoea following such prescriptions. Co-amoxiclav is associated with greater risk of AAD.
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