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Arch Intern Med. 2010 Apr 26;170(8):683-90. doi: 10.1001/archinternmed.2010.65.

Association of interruptions with an increased risk and severity of medication administration errors.

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  • 1Health Informatics Research and Evaluation Unit, Faculty of Health Sciences, University of Sydney, PO Box 170, Lidcombe 1825, NSW, Australia.



Interruptions have been implicated as a cause of clinical errors, yet, to our knowledge, no empirical studies of this relationship exist. We tested the hypothesis that interruptions during medication administration increase errors.


We performed an observational study of nurses preparing and administering medications in 6 wards at 2 major teaching hospitals in Sydney, Australia. Procedural failures and interruptions were recorded during direct observation. Clinical errors were identified by comparing observational data with patients' medication charts. A volunteer sample of 98 nurses (representing a participation rate of 82%) were observed preparing and administering 4271 medications to 720 patients over 505 hours from September 2006 through March 2008. Associations between procedural failures (10 indicators; eg, aseptic technique) and clinical errors (12 indicators; eg, wrong dose) and interruptions, and between interruptions and potential severity of failures and errors, were the main outcome measures.


Each interruption was associated with a 12.1% increase in procedural failures and a 12.7% increase in clinical errors. The association between interruptions and clinical errors was independent of hospital and nurse characteristics. Interruptions occurred in 53.1% of administrations (95% confidence interval [CI], 51.6%-54.6%). Of total drug administrations, 74.4% (n = 3177) had at least 1 procedural failure (95% CI, 73.1%-75.7%). Administrations with no interruptions (n = 2005) had a procedural failure rate of 69.6% (n = 1395; 95% CI, 67.6%-71.6%), which increased to 84.6% (n = 148; 95% CI, 79.2%-89.9%) with 3 interruptions. Overall, 25.0% (n = 1067; 95% CI, 23.7%-26.3%) of administrations had at least 1 clinical error. Those with no interruptions had a rate of 25.3% (n = 507; 95% CI, 23.4%-27.2%), whereas those with 3 interruptions had a rate of 38.9% (n = 68; 95% CI, 31.6%-46.1%). Nurse experience provided no protection against making a clinical error and was associated with higher procedural failure rates. Error severity increased with interruption frequency. Without interruption, the estimated risk of a major error was 2.3%; with 4 interruptions this risk doubled to 4.7% (95% CI, 2.9%-7.4%; P < .001).


Among nurses at 2 hospitals, the occurrence and frequency of interruptions were significantly associated with the incidence of procedural failures and clinical errors.

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