Effects of therapeutic drug monitoring criteria in a computerized prescriber-order-entry system on the appropriateness of vancomycin level orders

The effects of therapeutic drug monitoring (TDM) criteria in a computerized prescriber-order-entry (CPOE) system on the appropriateness of orders for vancomycin levels were evaluated. Vancomycin TDM criteria were developed and implemented in a CPOE system. These criteria were displayed via a pop-up alert message when vancomycin levels were ordered and included directions for appropriate timing and justification for routine monitoring. Data for two groups of adult inpatients who had vancomycin levels ordered before and after criteria implementation were compared. Medical records were retrospectively reviewed for these patients to collect information regarding patient demographics, vancomycin dosage and indication, concurrent antibiotics and nephrotoxic agents during vancomycin therapy, length of stay, duration of vancomycin therapy, and number of vancomycin levels drawn. The primary outcome was the percent change in appropriate vancomycin levels ordered after criteria implementation. A total of 200 patients were analyzed, 100 in each group. The percentage of appropriate orders for vancomycin levels significantly increased after criteria implementation (from 58% to 68%, p = 0.02). The greatest effect on appropriateness occurred with the first level ordered (52% versus 70% in the preimplementation and postimplementation groups, respectively; p = 0.01). The majority of inappropriate levels were due to improper timing of sample collections, accounting for 55% of the inappropriate levels evaluated. A significant increase in the number of appropriately ordered and drawn serum vancomycin levels occurred after implementation of TDM criteria in the hospital's CPOE system. The majority of orders that were deemed inappropriate were due to improper timing of laboratory collection.