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

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.

Risk Factors for Adverse Drug Events Among Older Adults in the Ambulatory Setting

OBJECTIVES

To gather information on patient-level factors associated with risk of adverse drug events (ADEs) that may allow focus of prevention efforts on patients at high risk.

DESIGN

Nested case-control study.

SETTING

Large multispecialty group practice in New England.

PARTICIPANTS

All Medicare enrollees cared for by a multispecialty group practice during 1 year (N=30,397 person-years from July 1, 1999, through June 30, 2000). For each patient with an ADE, a control was randomly selected.

MEASUREMENTS

Data were abstracted from medical records on age, sex, comorbidities, and medication use at the time of the event.

RESULTS

ADEs were identified in 1,299 older adults. Independent risk factors included being female and aged 80 and older. There were dose-response associations with the Charlson Comorbidity Index and number of scheduled medications. Patients taking anticoagulants, antidepressants, antibiotics, cardiovascular drugs, diuretics, hormones, and corticosteroids were at increased risk. In the analysis of preventable ADEs, the dose-response relationship with comorbidity and number of medications remained. Patients taking nonopioid analgesics (predominantly nonsteroidal antiinflammatory drugs and acetaminophen), anticoagulants, diuretics, and anti-seizure medications were at increased risk.

CONCLUSION

Prevention efforts to reduce ADEs should be targeted toward older adults with multiple medical conditions or taking multiple medications, nonopioid analgesics, anticoagulants, diuretics, and antiseizure medications.

Incidence and preventability of adverse drug events among older persons in the ambulatory setting

CONTEXT

Adverse drug events, especially those that may be preventable, are among the most serious concerns about medication use in older persons cared for in the ambulatory clinical setting.

OBJECTIVE

To assess the incidence and preventability of adverse drug events among older persons in the ambulatory clinical setting.

DESIGN, SETTING, AND PATIENTS

Cohort study of all Medicare enrollees (30 397 person-years of observation) cared for by a multispecialty group practice during a 12-month study period (July 1, 1999, through June 30, 2000), in which possible drug-related incidents occurring in the ambulatory clinical setting were detected using multiple methods, including reports from health care providers; review of hospital discharge summaries; review of emergency department notes; computer-generated signals; automated free-text review of electronic clinic notes; and review of administrative incident reports concerning medication errors.

MAIN OUTCOME MEASURES

Number of adverse drug events, severity of the events (classified as significant, serious, life-threatening, or fatal), and whether the events were preventable.

RESULTS

There were 1523 identified adverse drug events, of which 27.6% (421) were considered preventable. The overall rate of adverse drug events was 50.1 per 1000 person-years, with a rate of 13.8 preventable adverse drug events per 1000 person-years. Of the adverse drug events, 578 (38.0%) were categorized as serious, life-threatening, or fatal; 244 (42.2%) of these more severe events were deemed preventable compared with 177 (18.7%) of the 945 significant adverse drug events. Errors associated with preventable adverse drug events occurred most often at the stages of prescribing (n = 246, 58.4%) and monitoring (n = 256, 60.8%), and errors involving patient adherence (n = 89, 21.1%) also were common. Cardiovascular medications (24.5%), followed by diuretics (22.1%), nonopioid analgesics (15.4%), hypoglycemics (10.9%), and anticoagulants (10.2%) were the most common medication categories associated with preventable adverse drug events. Electrolyte/renal (26.6%), gastrointestinal tract (21.1%), hemorrhagic (15.9%), metabolic/endocrine (13.8%), and neuropsychiatric (8.6%) events were the most common types of preventable adverse drug events.

CONCLUSIONS

Adverse drug events are common and often preventable among older persons in the ambulatory clinical setting. More serious adverse drug events are more likely to be preventable. Prevention strategies should target the prescribing and monitoring stages of pharmaceutical care. Interventions focused on improving patient adherence with prescribed regimens and monitoring of prescribed medications also may be beneficial.