Department of Pharmacy, Withington Hospital, Nell Lane, West Didsbury, Manchester M20 2LR, UK
Sir,
The review by Gould & Jappy1 constitutes a useful survey of antimicrobial use over a decade, and on the face of it appears to suggest an overall increase of 17% in antibiotic usage. They use defined daily doses (DDDs) as a quantitative indicator of antibiotic consumption and 1000 patient days as a population denominator to correct for hospital activity.
Whilst the concept of a patient bed day has been one that has commonly been used in the epidemiology of medicine usage, its interpretation can be problematical. For example, 1000 patient days can be represented by 100 patients staying in hospital for 10 days or 500 staying 2 days. With the drive towards minimum invasive surgery and day cases, most acute hospitals have seen a fall in the average duration of stay and a considerable increase in the numbers of patients being treated by the institution.
A redefinition of the patient activity denominator to, say, deaths and discharges, admissions or the more recent currency of Finished Consultant Episodes (FCEs), might provide a more meaningful estimate of patient throughput, and may offer an explanation as to why our medicine budgets are increasing by at least 10% each year.2 An understanding of the relationship between activity and cost could then be used to predict realistic medicine budgets.
Notes
J Antimicrob Chemother 2000; 46: 639
* Tel: +44-161-291-3910; Fax: +44-161-291-3906; E-mail: Jonathan.Cooke{at}man.ac.uk
Reference
1 . Gould, I. M. & Jappy, B. (2000). Trends in hospital antimicrobial prescribing after 9 years of stewardship. Journal of Antimicrobial Chemotherapy 45, 9137.[ISI][Medline]
2 . Cooke, J. (1994). The practical impact of pharmacoeconomics on institutional managers. Pharmacoeconomics 6, 28997.[ISI][Medline]