Landmark study finds medication errors increase with interruptions

26 April 2010

Interruptions to nurses contributed to a staggering 80.2 per cent medication error rate, including clinical errors or procedural failures, according to a study by the University of Sydney's Health Informatics Research and Evaluation Unit published in the Archives of Internal Medicine today.

Lead Author, Prof. Johanna Westbrook
Lead Author, Prof. Johanna Westbrook

The study is the first to record the impact of interruptions to nurses during their day-to-day work, including medication delivery and IV administration.

Researchers observed a voluntary sample of 98 nurses in two unnamed Australian hospitals. The nurses were observed preparing and administering 4271 medications to 720 patients from September 2006 to March 2008.

Each interruption was associated with a 12.7 per cent increase in clinical/medication errors and a 12.1 per cent increase in procedural failures such as failing to check a patient's ID with their medication chart.

Lead author, Professor Johanna Westbrook said the study showed the more interruptions nurses received, the greater the number of errors.

"The risk of a patient experiencing a major clinical error doubled in the presence of four or more interruptions," she said.

"Without interruption, the estimated risk of a major error was just 2.3 per cent, but with four interruptions this risk doubled to 4.7 per cent.

"We found as interruptions increased within a single drug administration, the greater the severity of the error. Interruptions occurred in 53 per cent of all drug administrations and overall, 25 per cent of all administrations had at least one clinical error.

"Only 41.3 per cent of drug administrations were administered with the correct patient identification procedure made."

Incorrect timing of medication delivery was the most frequent clinical error, but only 4.1 per cent were rated as severe. Wrong IV administration rate was the second most frequent clinical error with 35.7 per cent rated as severe.

Professor Westbrook said nursing experience provided no protection against clinical errors and was actually associated with higher procedural failure rates.

"Our study showed that part-time and less experienced nurses had lower rates of procedural failures. Not checking the patient's identification against their medication chart was the most frequent procedural failure. Full-time, more experienced nurses may believe they can easily visibly identify patients and thus a formal identification process is not necessary. However, recognising a patient does not ensure that you have the correct medication chart.

"One third of all medication errors that cause harm to patients arise during medication administration. The principal standard for medication administration is the "five rights" (right patient, right drug, right dose, right time and right route). But despite this principal being an essential part of nurses' education, medication administration errors are frequent."

However, Professor Westbrook said interruptions were very much a part of the hospital environment.

"Clinical environments are highly interruptive, with studies of emergency departments reporting rates of six to 15 interruptions per physician, per hour," she said.

"And in hospitals, the incidence of medication errors is considerable, with estimates as high as one per patient, per day in some settings.

"Interruptions have been implicated in previous surveys of adverse incidents, but evidence of the relationship between interruptions and clinical errors has been scarce to date.

"This is the first substantial study that has demonstrated a direct association between interruptions and clinical error in hospitals.

"Future research is needed both to better understand why interruptions occur and to develop strategies that allow staff to make judgements about when it is safe to interrupt and how to manage interruptions by others."

Media contact: Rachel Gleeson, University of Sydney Media Officer on 0403 067 342, (02) 9351 4312 or