Factors influencing antimicrobial utilization at a university hospital during a period of 11 years

A number of factors may influence antibiotic prescribing. The objective of this study was to identify trends in antimicrobial prescribing during a period of 1 years at the University Hospital Center Rijeka (UHC), Croatia, and to identify possible factors that might have influenced changes in prescribing patterns. This may help in establishing criteria for future intervention.Antimicrobial utilization was evaluated retrospectively for the 11-year period from 1990-2000. It was measured in defined daily doses (DDDs) per 100 bed days using the ATC Index with DDDs 2000.During the investigation period, marked differences were noted in total and individual antimicrobial consumption. In the first 4 years of this study, the utilization of all groups of antimicrobials decreased, while in its second part (i.e. from 1995-1997) an increase in utilization of all antimicrobial groups occurred. Changes in utilization of groups of antimicrobials did not coincide completely with the changes in total antimicrobial utilization. The most prominent changes were a decrease in penicillin and cephalosporin utilization, and an increase of macrolides and aminoglycosides utilization from 1997-2000. Ampicillin and cefalexin were mostly prescribed as single antibiotics during a 5-year period (1990-1995) with the exception of 1 year (1994) when a marked decline in antimicrobial utilization was noted. In the following years, amoxicillin and amoxicillin with enzyme inhibitor became the most-used antimicrobials.Various factors influenced antimicrobial utilization during the investigation period. There were factors that directly influenced prescribing, e.g. the physicians' prescribing habit, guidelines, policy and formulary. Other factors directly influenced utilization, e.g. availability of a drug through purchasing, dispensing, procurement, pricing etc.