Clinical research study
The incidence of adverse drug events in two large academic long-term care facilities

https://doi.org/10.1016/j.amjmed.2004.09.018Get rights and content

Purpose

To assess the incidence of and risk factors for adverse drug events in the long-term care setting.

Methods

We performed a cohort study of all long-stay residents of two academic long-term care facilities over a period of up to 9 months during 2000 to 2001. We assessed the number of adverse drug events, the severity of events (classified as less serious, serious, life threatening, or fatal), and whether the events were preventable. A case-control study was nested within the prospective study to identify resident-level risk factors for the occurrence of adverse drug events.

Results

There were 815 adverse drug events, of which 42% were judged preventable. The overall rate of adverse drug events was 9.8 per 100 resident-months, with a rate of 4.1 preventable adverse drug events per 100 resident-months. Errors associated with preventable events occurred most often at the stages of ordering and monitoring. Residents taking medications in several drug categories were at increased risk of a preventable adverse event. In multivariate analyses, the adjusted odds ratio was 3.4 (95% confidence interval [CI]: 2.0 to 5.9) for those taking antipsychotic agents, 2.8 (95% CI: 1.6 to 4.7) for those taking anticoagulants, 2.2 (95% CI: 1.2 to 4.0) for those taking diuretics, and 2.0 (95% CI: 1.1 to 3.7) for those taking antiepileptics.

Conclusion

Our findings reinforce the need for a special focus on the ordering and monitoring stages of pharmaceutical care for preventing adverse drug events in the long-term care setting. Patients taking antipsychotic agents, anticoagulants, diuretics, and antiepileptics are at increased risk.

Section snippets

Study setting

This study was conducted in two large academic long-term care facilities in Connecticut and Ontario, Canada. The two facilities have a total of 1229 beds. Patients residing in areas of the facilities related to short-term care (eg, subacute care, hospital-level care, or rehabilitation) were not included.

The study was conducted over an 8-month period in one facility (December 2000 through July 2001) and a 9-month period in the other facility (December 2000 through August 2001). The study was

Results

In the two study sites combined, 1247 long-term care residents (mean [± SD] age, 86 ± 8 years) yielded 8336.4 resident-months of observation time. A comparison of this sample with the overall U.S. population of nursing home residents demonstrated similar sex characteristics,14 but the study sample was somewhat older. In the United States in 1999, 72% of nursing home residents were women and 78% of all residents were aged 75 years or older, compared with 72% who were women and 92% who were 75

Discussion

We found that adverse drug events occurred frequently and were often preventable in the two academic long-term care facilities that participated in this study. Serious, life-threatening, and fatal adverse drug events were more likely to be preventable than were less severe events. Most errors associated with preventable events occurred at the prescribing and monitoring stages of pharmaceutical care.

Our study offers the opportunity to compare observed adverse drug event rates with those

Acknowledgment

We thank Mary Ellen Stansky and Jackie Cernieux, MPH, for their assistance with technical aspects of this study, and Bessie Petropoulos for assistance with manuscript preparation.

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Supported by a grant from the Agency for Healthcare Research and Quality (HS010481), Rockville, Maryland.

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