Cost-effectiveness of prospective and continuous parenteral antibiotic control: experience at the Palo Alto Veterans Affairs Medical Center from 1987 to 1989.

PURPOSE

Controlling inappropriate antibiotic usage is a major focus for hospital quality assurance and cost-containment programs. We assessed the impact of strengthening a parenteral antibiotic control policy and instituting continuous infectious disease service (IDS) reviews of the appropriateness of antimicrobial therapy on cost and patient outcomes.

PATIENTS AND METHODS

All patients receiving intravenous antibiotics during a 3.5-year period from 1986 to 1989 were included in either the pre- or post-policy study group. Antibiotic costs 16 months before were compared with antibiotic costs 26 months after implementation of a new policy to restrict inappropriate usage of (1) broad-spectrum antibiotics when not necessary, (2) expensive agents when a less costly agent could be used, and (3) an excessive dosage or interval. Patient subgroups treated 4 months before and 4 months after policy implementation were compared further within diagnosis-related group (DRG) assignments using patient demographic, cost, and outcome measures.

RESULTS

The average monthly antibiotic costs during the 26-month post-policy period were $7,600 less than during the 16-month pre-policy period (p less than 0.0001), resulting in an average yearly drug cost reduction of $91,200. The IDS team altered therapy in 611 (34.5%) of 1,769 reviews of antibiotic usage during the 26-month period. The comparisons among similar patient groups by DRG classification revealed the average number of antibiotic doses per study patient admission was decreased 24% (p = 0.005) and drug costs were reduced 32% (p = 0.004) after policy implementation. In two DRG categories (i.e., respiratory infections plus pneumonia), patients in the post-policy group had a 33% decrease in average number of doses (p = 0.05) and 45% decrease in antibiotic costs (p = 0.04) compared with the pre-policy group. Similar trends were observed in most DRG categories. There was an average $70 per admission decrease in drug cost and a reduction of eight antibiotic doses per admission after policy initiation. The overall prevalence of deaths (p = 0.22) and average length of antibiotic therapy (p = 0.29) were less in the post-policy period despite group similarities in patient characteristics and lengths of hospital stay.

CONCLUSION

Antibiotic control policies can be developed to ensure quality care and can be designed to select for cost-effective agents. Prospective and continuous monitoring of antibiotic usage by the IDS resulted in a significant and sustained reduction in antibiotic costs without detrimental effect on the length of therapy or deaths.