Delirium Is a Major Risk for Hospitalized Elderly
Delirium Is a Major Risk for Hospitalized Elderly
By Joan Unger RN, MS, ARNP-C
Summary—Delirium is strongly associated with increased morbidity and mortality in elderly hospitalized patients. It is often overlooked or misdiagnosed and accounts for $1-$2 billion in health care costs annually. Many times it is the first or only clue to serious illness — such as severe infection, heart attack, or pneumonia — in the elderly. Up to 60% of the elderly experience delirium during hospitalization, and mortality rates among patients with delirium are 2-20 times higher than those without. One study found documentation for the condition in the charts of only 5% of delirious hospital patients. This study demonstrates a significant benefit to early diagnosis and preventive intervention for elderly hospitalized patients with delirium.1
Delirium, also known as acute confusional state, complicates the hospital stay for more than 2.3 million elderly and results in the expenditure of more than $4 billion (1994 statistics) in Medicare funds annually. Studies indicate that up to 60% of hospitalized elderly will experience delirium during hospitalization, and mortality rates in patients with delirium are 2-20 times higher than those without. Yet it is a common serious disorder that is underdiagnosed and commonly misdiagnosed. One study showed only 5% of hospital patients with delirium had the diagnosis documented at discharge. Most earlier studies focused on identifying risk factors and looked at the treatment of delirium. The goal of this study was to identify effective primary preventive interventions.1
Study Methodology
Investigators recruited study subjects from a pool of 2434 patients admitted to one of three general medicine units at a large teaching hospital over a period of three years. Inclusion criteria were:
• admission to one of the selected units;
• at least 70 years of age;
• no delirium on admission;
• and an intermediate or high risk for delirium at baseline.
A prospective, individual matching strategy was chosen for this controlled clinical trial as an alternative to randomization because bed availability was a problem on the selected units. Study patients were matched with control patients according to sex, age within five years, and baseline risk of delirium rated as intermediate or high. Researches defined a predictive model to quantify delirium risk as intermediate or high based on whether patients exhibited three or four of the following risk factors identified by previous studies:2,3 visual impairment, cognitive impairment, severe illness, or high ratio of blood urea nitrogen to creatinine.
All subject assessments were performed by research staff who were unaware of the study parameters and had no role in the selected interventions. Assessment standardization and inter-rater reliability measurements validated the consistency of ratings. The screening interview used a number of patient assessment tools. (See table showing assessment instruments, qualities measured, and scoring methods, inserted in this issue.) Researchers also had a family member describe the patient’s cognitive functioning prior to admission, report any recent changes in cognition, and complete the modified Blessed Dementia Rating Scale. The observer-rated score on this scale has been found to correlate directly with post-mortem findings of the number of neuritic plaques in the brain.
Researchers used the ratio of blood urea nitrogen to creatinine (measured in milligrams per deciliter) as an index of dehydration. All assessments were completed within 48 hours of admission, and patients were evaluated daily until discharge. At discharge, or hospital day five, subjects’ risk factors for delirium were reassessed. After discharge, investigators reviewed medical records for evidence of delirium.
Intervention Strategy
Researchers identified six additional risk factors for delirium, including cognitive impairment, dehydration, hearing impairment, immobility, sleep deprivation, and visual impairment. An interdisciplinary team was trained to implement standardized intervention protocols called the Elder Life Program, which was directed toward preventing delirium. The team consisted of a geriatric nurse-specialist, two Elder Life Program specialists, a certified therapeutic recreation specialist, physical therapy consultant, a geriatrician, and trained volunteers. Targeted interventions included cognitive stimulation, sleep enhancement strategies, increased mobilization, visual and/or hearing aids if needed, and early recognition of dehydration with encouragement of oral fluid intake.
Control subjects received "usual care" consisting of standard hospital services provided by physicians, nurses, physical therapists, pharmacists, and nutritionists.
Study Results
Researchers found that characteristics of the subjects in the intervention and usual-care groups did not differ significantly. The rate of incidence of delirium was significantly higher in the usual-care group than in the intervention group (15% vs. 9.9%, p = 0.02). The cumulative incidence of delirium using Kaplan-Meier estimates at median length of hospital stay were 0.145 for the usual-care group and 0.100 for the intervention group. A matched odds ratio of 0.60 (95% confidence interval) in matched multivariable analyses showed a substantial reduction in risk associated with intervention. The group receiving usual care had a higher number of days of delirium when compared with the intervention group (161 vs. 105 days, p = 0.02). Episodes of delirium also were higher in the usual-care group when compared with the intervention group (90 vs. 62, p = 0.03). The episodic effect seemed to occur from the results of intervention during the first episode of delirium rather than from the interventions on recurring episodes.
Severity scores and recurrence rates did not differ significantly between the subject groups. In the group at intermediate risk for delirium, intervention significantly lowered the rate of incidence of delirium, but in the group at high risk for delirium, the decrease in incidence was not statistically significant. Subject reassessment on day five or at discharge demonstrated a significant decrease in the use of sleep medication, a significant improvement in orientation score, and trends toward improvement in activities of daily living and Whisper Test scores in the intervention group. Early vision correction showed a trend toward improvement in this group. Significantly fewer risk factors were found in the intervention group than in the usual care group.
Implications for Practice
This study presents a number of important considerations for the primary care practitioner dealing with the elderly both in hospital and in outpatient settings for several reasons. Delirium:
• is common in the elderly, especially the hospitalized;
• is highly associated with morbidity and mortality;
• significantly extends the length of hospital stay;
• drives up hospital costs and is responsible for estimated annual health care costs of $1-$2 billion;
• is a serious condition that may signal an underlying life-threatening problem such as severe infection, myocardial infarction, or pneumonia;
• predicts cognitive decline, resulting in loss of independent living;
• and is unrecognized by primary treating clinicians in 32-67% of cases.4
This study points out the need for practitioners to be aware of the risks and alert to signs and symptoms of delirium in the elderly. The condition often is missed or confused with depression and/or dementia. The study demonstrates that preventive strategies and early diagnosis with appropriate intervention can reduce the incidence and severity of delirium in hospitalized elderly.
References
1. Inouye S, Bogardus S, Charpentier P, et al. A multicomponent intervention to prevent delirium in hospitalized older patients. NEJM 1999;340:669-676.
2. Inouye S, Viscoli C, Horwitz R, et al. A predictive model for delirium in hospitalized elderly medical patients based on admission characteristics. Ann Intern Med 1993;119:474-481.
3. Elie M, Cole M, Primeau F, et al. Delirium risk factors in elderly hospitalized patients. J Gen Intern Med 1998;13:204-212.
4. Jacobson S. Geriatric psychiatry: Delirium in the elderly. Psychiatric Clinics of North America 1997;20:91-111.
Additional Reading
• Inouye S, van Dyck C, Alessi C, et al. Clarifying confusion: The Confusion Assessment Method: A new method for detection of delirium. Ann Intern Med 1990;113:941-948.
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