Importance of nondrug costs of intravenous antibiotic therapy

Costs are one of the factors determining physicians' choice of medication to treat patients in specific situations. However, usually only the drug acquisition costs are taken into account, whereas other factors such as the use of disposable materials, the drug preparation time and the staff workload are insufficiently taken into consideration. We therefore decided to assess true overall costs of intravenous (IV) antibiotic administration by performing an activity-based costing approach.

A prospective survey on costs and workload by means of a time and motion analysis and activity-based costing was performed in a 605-bed secondary referral centre with 20 intensive care unit beds. The subjects were 50 consecutive patients admitted to our hospital with community-acquired pneumonia or intra-abdominal infections requiring treatment with IV antibiotics. A time and motion analysis of 103 routine acts of preparing and administering IV antibiotics was performed in the intensive care unit and in the Department of Internal Medicine. To measure the entire process an inventory and work flowchart were made using detailed questionnaires completed by members of the nursing staff, the medical staff and the pharmacy staff. In addition, questionnaires were distributed to management and secretarial staff to determine additional overhead costs. The average costs for different methods of IV antibiotic administration were then compared by timing all steps in the process. Four different methods of drug administration were used: administration by volumetric pump, administration by syringe pump, administration by 'unaided' infusion bag, and administration by direct IV injection.

The average times required for each of these procedures, including preparation and administration of the drug, were 4:49 +/- 2:37, 4:56 +/- 2:03, 5:51 +/- 3:33 and 9:21 +/- 2:16 min (mean minutes:seconds +/- standard deviation), respectively. When the costs for expended staff time and materials (not including drug costs) were calculated this resulted in average costs of 5.65, 7.28, 5.36 and 3.83, respectively, for administration of each dose of antibiotics. These costs represent between 11% and 53% of the total daily costs of antibiotic therapy. Compared with the acquisition costs, these indirect costs ranged from 13% to 113%. Not included in this comparison is the time required for insertion of an IV catheter, which was found to be 10:15 +/- 6:31 min with an average calculated cost of 9.17.

Total costs of IV antibiotic administration are formed not only by the costs of the drugs themselves, but also, to a substantial degree, by the time expended by medical and nursing staff, costs of disposable materials and overhead costs. Physicians making decisions regarding the use of specific medications in intensive care unit patients should take these factors into account. Use of IV antibiotics is associated with considerable workload and additional costs that can exceed the acquisition costs of the medications themselves.