Overdose Rate of Drugs Requiring Renal Dose Adjustment: Data Analysis of 4 Years Prescriptions at a Tertiary Teaching Hospital

To determine the overdose rate of drugs that require renal dose adjustment and factors related with overdose.

Total of 23,635,210 records of prescriptions and laboratory data of inpatients at a tertiary teaching hospital for the period from January 2002 to December 2005.

A clinical data mart was constructed. A knowledge base containing dose adjusting information about 56 drugs was built. One day dose was compared to the reference dose adjusted to the patient’s renal function.

Considering the patient’s renal function, 5.3% of drug doses were excessive. The overdose rate in the patients with moderate to severe renal insufficiency was 28.2%. Only 25% of physicians were responsible for 50.6% of the overdoses. Of 56 drugs studied, 10 drugs, including ranitidine, amoxicillin, and piperacillin/tazobactam, were involved in 85.4% of the overdoses. The physicians with high overdose rate had patients with more impaired renal function (correlation coefficient = 0.192, P < .001). There were negative correlation between clinical experiences of physician and overdose rate (correlation coefficient = −0.221, P < .001) and workload of prescription (correlation coefficient = −0.446, P < .001), when excluding interns from the analyses. There was positive correlation between workload of prescription and overdose rate (correlation coefficient = 0.361, P < .001).

A clinical data mart was useful to analyze the vast amount of electronic hospital data. Drug overdose is quite common among inpatients with renal insufficiency. Only a few drugs are responsible for most of drug overdoses. The physicians’ clinical experience, workload of prescriptions, and patients’ renal function are correlated with drug overdose.