Medication errors: the impact of prescribing and transcribing errors on preventable harm in hospitalised patients

Medication errors (MEs) affect patient safety to a significant extent. Because these errors can lead to preventable adverse drug events (pADEs), it is important to know what type of ME is the most prevalent cause of these pADEs. This study determined the impact of the various types of prescribing (administrative, dosing and therapeutic) and transcribing errors on pADEs in hospitalised patients.

During a 5-month period, data for patients admitted to a total of five internal medicine wards of one university and one teaching hospital in The Netherlands were prospectively collected by chart review. In each hospital, MEs were detected and classified by the same pharmacist, using the classification scheme for MEs developed by The Netherlands Association of Hospital Pharmacists. The primary outcome measure was the prevalence of pADEs during hospital stay. In consensus meetings, five pharmacists assessed the causal relationship between MEs and pADEs. The association between type of ME and pADEs was determined by a multivariate regression analysis taking into account potential confounders.

The study included 592 hospital admissions with 7286 medication orders (MOs), of which 60% contained at least one prescribing or transcribing error. 1.4% of all MOs led to pADEs, concerning 14.8% of all admitted patients. The total number of pADEs was 103, and in 92 of these cases patients experienced temporary harm, in eight cases hospital admission was prolongued, two cases were life-threatening, and one was fatal. Therapeutic errors were most strongly associated with pADEs (OR 1.98; 95% CI 1.53 to 2.56).

Although many prescribing and transcribing errors occur in the process of medication use of hospitalised patients, a minority lead to pADEs. In particular, therapeutic errors are the cause of these pADEs and are therefore clinically relevant. Intervention and prevention programmes should primarily focus on this type of medication error.