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OBJECTIVE: To examine utilization and outcomes of intensive care unit (ICU) use for the elderly in the United States.
DESIGN: We used 1992 data from the Health Care Financing Administration to examine ICU utilization and mortality by age and admission reason for hospitalizations of elderly Medicare beneficiaries.
MAIN RESULTS: Use of the ICU was least likely for the oldest elderly overall (85+ years, 21.1% of admissions involved ICU; 75–84 years, 27.9%; 65–74 years, 29.7%), but more likely during surgical admissions. Eighty-three percent of the Medicare patients who received intensive care survived at least 90 days. Of the oldest elderly, 74% survived. Even among the 10% most expensive ICU hospitalizations, 77% of all patients and 62% of those 85 years and older survived at least 90 days.
CONCLUSIONS: The likelihood of ICU use among these elderly decreased with age, especially among those 85 years or older. Diagnostic mix importantly influenced ICU use by age. The great majority of the elderly, including those 85 years and older and those receiving the most expensive ICU care, survived at least 90 days.
Aggressive medical care of the elderly, especially the oldest elderly (85 years and older), is an issue under vigorous discussion. The intensive care unit (ICU) is the locus of a large part of aggressive care, accounting for 20% to 30% of hospital care costs (approximately $62 billion in 1992).1 No national population-based studies have examined patterns of ICU use by the elderly or clinical outcomes of such use. Studies using data from individual hospitals2–9 or states10,11 have reached different conclusions about clinical patterns of ICU use and subsequent mortality in the elderly.
In this article, we review these issues for all elderly Medicare-funded hospitalized patients during a study year, examining ICU use by clinical diagnosis and by age. We also determine death rates of patients in hospital and within 90 days of admission as a function of ICU use and age, paying special attention to the oldest elderly and to the most expensive 10% of hospitalizations and patients.
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Although in general the patients aged 85 years and older were less likely to be admitted into the ICU than the patients between 65 and 84 years (Table 1), ICU use was more closely associated with medical conditions and treatments than with age (Fig. 1). When examining the common DRG groups, we observed a mixed pattern in ICU use with respect to age. The patients aged 85 years and older were less likely to receive intensive care in general medical admissions, but more likely to receive it in procedural and surgical admissions (Fig. 1). In another study from our group, patients aged 85 years and older were more likely than the other age groups to be hospitalized for general medical treatments and less likely to be admitted for major procedures.13 Thus, the major reason for lower ICU use among the group aged 85 years and older in the present study is probably that more of their hospital admissions were for general medical treatments, in which intensive care is less likely regardless of age. However, older patients admitted for procedures were usually more likely to use intensive care than younger patients (Fig. 1).
Our finding that the oldest elderly were less likely to be admitted for surgical procedures is generally consistent with a recent study using the data of five medical centers participating in the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT). That study shows that older age is associated with higher rates of decisions to withhold ventilator support, surgery, and dialysis even after adjustment for differences in patients' prognoses and preferences.14 In our data, however, the oldest elderly admitted for surgical admissions were more likely to be admitted to an ICU, suggesting no age bias against the oldest elderly in receipt of intensive care. A possible explanation is that physicians carefully selected only the most robust of the oldest group for surgery. This explanation is also consistent with our finding that patients admitted for surgical procedures were less likely to die (Table 3).
This observation may explain some conflicting findings about whether age determines ICU use for the elderly among prior studies.15 If a study is based on a specific medical condition, then the distribution of ICU use by age will be greatly influenced by the type of medical condition studied. Even if the age effect on ICU use is examined for a group of medical conditions, the aggregate result can be affected by the proportions of procedural and medical admissions selected. If a study sample is dominated by general medical admissions, it may be concluded that older patients use less intensive care; if the sample includes a high proportion of procedural admissions, the opposite conclusion may be drawn.
A major concern about ICU care is that this very expensive intervention may be overused, especially in the management of very elderly patients who are “at the end of their natural life spans.” Cher and Lenert,10 for example, defined “potentially ineffective care” for Medicare patients who used an ICU as the concurrence of death within 100 days of hospital discharge and resource use above the 90th percentile. We did not estimate resource use but did evaluate the total amount paid by HCFA. Although our analysis differs in detail from their cost calculation, a general comparison is interesting. The 90-day death rate of the 10% most expensive ICU hospitalizations in the present study was 20%, a 2% rate of potentially ineffective care for all Medicare hospitalizations with ICU care. This is much lower than the 4.8% estimate of the frequency of such an outcome for the California population Cher and Lenert studied. The difference is probably due to sample selection. The 4.8% rate of potentially ineffective care in their study is based on 15 DRG groups that have the highest 100-day mortality in ICU admissions, while the 2% rate in our study is based on all ICU admissions. In Cher and Lenert's study, the 4.8% of potentially ineffective care admissions accounted for 21.6% of total ICU resources. We cannot calculate the cost of ICU care from our data. However, the 2% of deaths among the most expensive hospitalizations in our study accounted for only 9.5% of the total amount paid by HCFA for all hospitalizations involving ICU care.
Clinical conclusions based on this type of analysis are speculative. Cost savings are possible only if the patients who die within a few months after the most expensive ICU care can be identified shortly after admission to hospital. There are as yet no accurate tools for identifying such patients prospectively without incurring the risk of denying appropriate care to the majority of elderly patients who are destined to survive for at least 3 months following ICU care.16–18 Of the most expensive hospitalizations in our study, over 60% of even the most elderly group survived, as did 84% of the 65- to 74-year-old-group. Moreover, only 5% of the oldest group received ICU care whose total hospital expenditure fell within the most expensive decile of ICU admissions. In addition, the percentage of the hospitalizations involving ICU care decreased with age, especially for the most elderly. Taken together, these observations suggest that only modest savings would accrue even if the ethically dubious decision were made to deny all ICU care for the very elderly; they also suggest that the term “potentially ineffective care” should be used with caution.
This study supports four specific conclusions. First, while the likelihood of ICU use following procedural admissions increased with age, the likelihood of ICU use following general medical admissions decreased with age. Second, although there was an association between age and ICU use, admission to the ICU was more highly associated with the admission diagnosis than with the age of the patient being admitted. Third, the likelihood of ICU use among the oldest hospitalized patients was lower than that for the younger population, since the oldest patients were less frequently admitted for procedural interventions, for which ICU use was highest. Finally, the substantial majority of all patients admitted to these ICUs survived for at least 90 days, including those 85 years and older and those whose hospital expenditures were in the most expensive decile of the Medicare payment for hospitalizations involving ICU care.