Abstract
The anatomical therapeutic chemical/defined daily dose system (DDD), recommended by the World Health Organization, uses drug consumption data and calculates the density of antimicrobial agent use and is used at many institutions. The day of therapy (DOT) is an index used to evaluate the density of antimicrobial agent use based on the duration of use and is not related to the daily dose. We determined DDD and DOT semiannually from September 1, 2008, to March 31, 2014, and calculated the ratio of DDD to DOT (DDD / DOT). The DDD / DOT ratio can be used to evaluate the change of the daily dose. We then compared these values and evaluated their effect on the resistance ratio for Pseudomonas aeruginosa. Six drugs were evaluated in this study: ceftazidime, cefozopran, cefepim, imipenem/cilastatin, meropenem, and ciprofloxacin. All drugs, except ciprofloxacin, showed a significant difference between DDD and DOT. The resistance ratio for Pseudomonas aeruginosa was not statistically correlated with three indexes (DDD, DOT, and DDD / DOT). The three indexes (DDD, DOT, and DDD / DOT) can be used to examine the usage trends of antimicrobial agents. However, these three indicators did not show any correlation with the susceptibility rate. Therefore, these indexes should be used on the basis of their characteristics.
