ANTIBIOTIC UTILIZATION IN THE DEPARTMENT OF SURGERY, SINGAPORE NATIONAL UNIVERSITY HOSPITAL

Abstract

A prospective study on antibiotic utilization in surgical patients at the Singapore National University Hospital was performed in two phases. Phase I study was to monitor the baseline pattern of antibiotic usage and in phase II, we evaluated the impact of guidelines on prophylactic usage. Patients were reviewed on a daily basis and all the pertinent information regarding diagnosis, types of surgical operations and procedures, operative findings, postoperative infectious complications and details of antibiotics usage (types of regimen, dose, route, time of administration of first dose, duration) were recorded. Patients were classified according to the type of surgical specialities and then subclassified according to the types of management - operations, procedures and conservative management. Antibiotics used were classified as prophylactic and therapeutic and were analysed. Antibiotics were used in 46% of 816 patients admitted during phase I and 49% of 893 patients admitted in phase II. In phase I, 56% underwent operations, 16% underwent procedures and 26% had conservative management. The corresponding numbers for 893 patients in phase II were 60%, 14% and 26% respectively. In both phases, 46% of patients undergoing operations received antibiotic prophylaxis. Seventy-seven percent to 78% (phase I - phase II) of the patients receiving antibiotic prophylaxis were given the first dose within 24 hours prior to surgery or in the operating theatre. The rest of the patients received the first dose either more than 24 hours before surgery or postoperatively. The choice of antibiotics varied widely with different surgical specialities, even in patients undergoing the same operations. In phase II, the impact of guidelines on antibiotic prophylaxis was observed in a few aspects: (a) more appropriate, cheaper, equally effective antibiotic alternatives were selected; (b) a decrease in the duration of prophylaxis, e.g. 28 % of patients in phase I received prophylaxis for 0 - 72 hours vs 49 % in phase II. These are best exemplified in the speciality neurosurgery, where the usage of recommended antibiotic cefazolin increased from 7% to 87% and the duration of prophylaxis reduced from 8.4 days to 3.2 days. The change in antibiotic utilization after the introduction of guidelines did not affect the rate of postoperative infectious complications but would have reduced medication costs.