Similarities in the consumption trajectory of antibacterial drugs in the outpatient care sector in Germany from 1986 to 2022: identification of shared patterns, correlation analysis of prescribed defined daily dose and assessment of underlying influences.

Antibacterial drugs are widely used in modern medicine, but their efficacy is increasingly threatened by antimicrobial resistance and ongoing supply shortages. This study examines the relationships among the 15 most prescribed antibacterial substances in Germany, analysing the correlations and trends of prescribed defined daily dose (DDD) of antibacterial drugs within the outpatient care sector under statutory health insurance from 1986 to 2022. Three groups of drugs with similar consumption trajectories were identified. The first group, including doxycycline, phenoxymethylpenicillin and sulfamethoxazole-trimethoprim, showed declining trends with stable trajectories, its similarities being confirmed by overlapping indications such as respiratory tract infections and declining usage due to guideline changes. The second group, comprising amoxicillin-clavulanic acid, cefpodoxime and pivmecillinam, displayed increasing trends with continuous trajectories. The third group, including ciprofloxacin, clarithromycin and cefaclor, shared declining trends with fluctuating trajectories, often related to bacterial resistance rates and substitution by other antibacterial drugs. Frequently prescribed substances often show many and strong correlations in consumption, indicating that they are more related with other substances and being susceptible to external factors, such as changes in costs, sudden events like the COVID pandemic or guideline recommendations. Less commonly used medicines, typically for niche indications, tend to have a more stable consumption trend and being less influenced by broader trends, resulting in fewer significant correlations. Distinguishing direct effects of changes in consumption from one drug to another from common but unrelated responses to external events remains a challenge, as there are many factors that can influence consumption. The findings provide a better understanding of the interdependencies in the consumption of the most commonly prescribed antibacterial drugs, improving the understanding of potential influencing factors to support strategies for rational prescribing and antimicrobial stewardship.