Medication errors in a neonatal intensive care unit. Influence of observation on the error rate

To study if medication error rate decreased as a consequence of a simple observation process of registering its occurrence.

Prescription and transcription processes were prospectively registered along two different period of time in a level III regional Neonatal Intensive Care Unit: a pilot phase, aimed to know the baseline drug error rate and a phase I, a pre-intervention phase, both part of a study designed to determinate the effect of a preventive strategy in drug error rate. Random drug prescriptions by physicians and their transcriptions by nurses were reviewed and registered by a hospital pharmacist. A drug error episode was registered if dosage, units, route and administration interval were incorrect, illegible or not indicated.

A significant reduction in the prescription error rate from 32.8% in the pilot phase to 19.2% in the pre-intervention study phase was observed (p< 0.001). Rates of incorrect dosing (13.6% vs. 5%) and lack of dose specification in the medical prescriptions (3.3% vs. 0.5%) dropped significantly but transcription errors did not.

The presence of a person reviewing and registering the drug records apparently had by itself a substantial positive effect on the overall drug error rate. This phenomenon known as the Hawthorne effect should be taken in consideration when evaluating the efficacy of any preventive intervention aimed at improving patient safety.