Trends in Antibiotic Use at a University Hospital: Defined or Prescribed Daily Doses? Patient Days or Admissions as Denominator?

Abstract

The DDD/100 patient days data format overestimated antibiotic use density changes in this hospital both in medicine (81% vs 48%) as well as in surgery (69% vs 39%) when compared with PDD/100 patient days. Due to changes in the number of admissions and length of stay over the years, the percent change between the two periods expressed in doses per 100 patient days in addition differed substantially from that estimated by using the DDD per admission or PDD per admission data format. Studies evaluating the evolution of hospital antibiotic use need to address the limitations and adequacy of the different data formats.

A 3 year survey on the use of antibacterial agents in five Italian hospitals

“…An example has been reported by de With et al 19 concerning co-amoxiclav. The DDD listed in the ATC/WHO index is 1 g for oral formulations and 3 g for parenteral formulations.…”

Quantitative Antibiotic Use in Hospitals: Comparison of Measurements, Literature Review, and Recommendations for a Standard of Reporting

“…When compared to DDDs, PDDs might provide a better estimate of true antibiotic use. However, large differences between DDD and PDD of a substance that is used in large amounts may result in substantial over-or underestimations not only of the true use of that certain drug, but also of overall antibiotics [16]. The main disadvantage is its lack of standardization, as the usually prescribed daily dose of an antibiotic may vary in different settings.…”

What’s the Best Way to Measure Antibiotic Use in Hospitals?

“…Finally, as noted by de With et al [1], an increase in antibiotic use -expressed in DDD or PDD per 100 patient days or per admission -may not correlate with the evolution of overall antibiotic purchasing costs. This may be explained by shifts in the use of certain antibiotics, i.e.…”

“…Furthermore, these DDDs do not reflect currently used doses for some antibiotics. As pointed out by de With et al [1] in their study, published in this issue of INFECTION, actually prescribed doses of several antibiotics are markedly higher than the DDDs, which are propagated by WHO. The study shows that using DDD per 100 patient days results in a marked overestimation of antibiotic use, compared to the expression of antibiotic use as prescribed daily doses (PDD) per 100 patient days.…”

“…Even this way of measuring antibiotic use may result in an overestimation of current antibiotic use in comparison to data from earlier years, as the length of stay of patients has gradually decreased over the years, resulting in a reduction of the magnitude of the denominator. Therefore, de With et al [1] suggest that it may be more appropriate to express measured data as PDD per admission, if data from different years are compared.…”