Impact of generic entry on hospital antimicrobial use: a retrospective quasi-experimental interrupted time series analysis

Background: the impact of antimicrobials generic entry (GE) is controversial. Their introduction could provide an economic benefit yet may also increase their consumption, leadingto a higher risk of resistance. Our aim was to analyze the impact of GE on trends of antimicrobialconsumption in an acute-care hospital. Methods: a retrospective quasi-experimental interrupted timeseries analysis was conducted at a 400-bed tertiary hospital in Barcelona, Spain. All antimicrobials forsystemic use for which a generic product entered the hospital from January 2000 to December 2019 were included. Antimicrobial consumption was expressed as DDD/100 bed days. Results: after GE, the consumption of cefotaxime (0.09,p< 0.001), meropenem (0.54,p< 0.001), and piperacillin-tazobactam (0.13,p< 0.001) increased, whereas the use of clindamycin (−0.03,p< 0.001) anditraconazole (−0.02,p= 0.01) was reduced. An alarming rise in cefepime (0.004), daptomycin (1.02),and cloxacillin (0.05) prescriptions was observed, despite not achieving statistical significance. Onthe contrary, the use of amoxicillin (−0.07), ampicillin (−0.02), cefixime (−0.06), fluconazole (−0.13),imipenem-cilastatin (−0.50) and levofloxacin (−0.35) decreased. These effects were noticed beyondthe first year post GE. Conclusions: GE led to an increase in the consumption of broad-spectrummolecules. The potential economic benefit of generic antibiotics could be diluted by an increase inresistance. Antimicrobial stewardship should continue to monitor these molecules despite GE.