Errors in the use of medication dosage equations

Arch Pediatr Adolesc Med. 1998 Apr;152(4):340-4. doi: 10.1001/archpedi.152.4.340.


Background: Calculation errors in prescribing are a well-recognized problem; however, no systematic studies of actual errors involving calculation or other errors in the use of drug dosage equations are available.

Objective: To characterize the nature and potential adverse consequences of actual prescribing errors involving dosage equations.

Design: Analysis of the characteristics of 200 consecutive prescribing errors with potentially adverse outcomes involving dosage equations.

Setting: Tertiary care teaching hospital.

Measurements: Potential adverse outcomes, prescribing service, medication class, and the process point at which the error was made.

Results: Errors most commonly involved children (69.5%) and antibiotics (53.5%). Forty-two percent of errors were considered to put the patient at risk for a serious or severe preventable adverse outcome. Errors in decimal point placement, mathematical calculation, or expression of dosage regimen accounted for 59.5% of dosage errors. The dosage equation was wrong in 29.5% of dosage errors.

Conclusions: The use of equations to determine medication dosages presents considerable risk to patients for errant dosing and subsequent adverse events or therapeutic failure. Errors may occur in any component of a dosage equation. Health care organizations should implement procedures to reduce the risk for errors resulting from the use of dosage equations.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Child
  • Child, Preschool
  • Dose-Response Relationship, Drug
  • Female
  • Hospitals, Teaching / statistics & numerical data
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Mathematics
  • Medication Errors / statistics & numerical data*
  • Medication Systems, Hospital / statistics & numerical data*
  • Middle Aged
  • New York
  • Pregnancy