Therapeutic failure among incident users of ß-lactam antibiotics: a real-world, cohort study, in primary care in Italy

Abstract

Background: β-lactam antibiotics are one of the most used medications for treatment of bacterial infections, mainly those involving the upper and lower respiratory tract. However, the development of antibiotic resistances largely reduced their effectiveness. Aims and Objectives: To compare β-lactam antibiotics in terms of treatment failure, which was evaluated as switch from one antibiotic to another β-lactam or another antibiotic class for the same indication. Methods: Using Health Search Database, we identified a cohort of patients with an incident prescription of β-lactam antibiotics. Patients were followed until the occurrence of switch to another antibiotic. Results: 178,256 incident users of β-lactams were identified and 1,172 (0.65%) of them were switched to another antibiotic within 30 days. Overall, amoxicillin-clavulanate reported the lowest (0,42%) degree of switching among β-lactams. Using multivariate logistic regression model and excluding incident users of parenteral antibiotics, amoxicillin-clavulanate showed the lowest risk of treatment failure compared to the other β-lactams, namely amoxicillin (odds ratio (OR) as compared to amoxicillin-clavulanate: 1.67 (95% CI 1.39-2.01)) and cefuroxime (OR: 3.05 (95% CI 2.16-4.29)). Estimating the switch rate stratified by indication of use, amoxicillin-clavulanate was associated with lowest rate of switch for lower respiratory tract infections (LRTIs), dental infections and middle ear infections. Conclusions: Our findings indicate that amoxicillin-clavulanate was associated to a lower rate of treatment failure when compared to other β-lactam antibiotics prescribed for LRTIs, dental infections and ear infections