Factors associated with reported preventable adverse drug events: a retrospective, case-control study

It has been reported that error occurs at some point during the medication use process in approximately 6% of medication doses administered in the inpatient setting. An estimated 1-10% of medication errors lead to patient harm; however, factors affecting the risk of harm from a medication error are undefined in the literature.

To identify independent factors affecting the risk of reported preventable adverse drug events (ADEs) (ie, medication errors contributing to patient harm) compared to medication errors that did not contribute to patient harm in a diverse patient population.

This was a retrospective, case-control study conducted at 3 hospitals within a large health system. Medication error reports from July 1, 2009, through June 30, 2010, were assessed. All reported medication errors determined to have contributed to patient harm were matched 1:1 with a medication error that did not contribute to harm. Data collected through review of the incident report and medical record included patient, provider, medication, and other related factors. Multivariable logistic regression was used to determine the relationship of potential factors to patient harm.

Of 4321 medication errors reported at study sites, 182 (4%) contributed to patient harm. Factors associated with increased independent risk of harm were 30-day readmission, time of day 0300-0659, and Institute for Safe Medication Practices (ISMP) high-alert medications. Factors associated with decreased independent risk of harm were multiple medication errors, occurrence during February or April, dispensing errors, and pharmacist review of medication order.

Health systems should develop programs to promote safe, conscientious use of ISMP high-alert medications, promote pharmacist review, control the use of cabinet overrides, and direct provider attention toward recently admitted patients. Efforts should be made to determine factors associated with risk of harm at local levels.