Researchers at a Dutch Hospital investigated the value of a clinical rule designed to improve antimicrobial dosing in critically ill patients with renal dysfunction in the ICU in terms of dosing adjustments, duration of exposure and costs, using a commercially available clinical decision support system (CDSS).

They retrospectively analysed data on 1788 patients admitted to the ICU in 2004 for more than 12 hours. The actual number of dosage adjustments without the support of the CDSS was compared with the theoretical number of dosage adjustments determined by the clinical rule in patients with moderate (creatinine clearance 10- 50ml/min) and severe (< 10ml/min) renal dysfunction. If dosage adjustment was omitted, the duration of excessive anti-infective dosing and extra drug costs involved was determined. The following findings were reported:

• Dosage adjustment of antimicrobials was omitted in 163 patients (86%) with moderate renal failure and 13 patients (54%) with severe renal failure.

• Excessive exposure was most frequently detected in patients receiving fluconazole and ciprofloxacin (median duration of 6 days).

• In the authors’ ICU alone, > €16,000 ($19,000) can be saved annually by adjusting the dosage according to renal function of frequently prescribed antimicrobials.

The researchers conclude “despite intensive monitoring of patients in the ICU, dosage adjustment of antimicrobials is often omitted. Implementing this clinical rule has the potential to contribute to a significant improvement in medication safety and is expected to generate substantial savings.” They acknowledged several limitations of their study such as its retrospective design, the focus on only the 10 most frequently prescribed antimicrobials though the clinical rule can be applied to all drugs where dosage reduction in renal failure is indicated, and the lack of data on side effects and outcomes.