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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptNIH Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
J Am Geriatr Soc. Author manuscript; available in PMC Nov 1, 2012.
Published in final edited form as:
PMCID: PMC3415302

The Importance of Delirium: Economic and Societal Costs

Douglas L. Leslie, Ph.D.1 and Sharon K. Inouye, M.D., MPH2,3


Although a number of studies have documented the negative clinical and economic consequences of delirium, interventions to prevent and treat delirium are infrequently implemented. The importance of delirium may continue to be underestimated until its societal and economic impact is documented. We outline the existing literature related to long-term sequelae and costs associated with delirium, and stress the importance of such research in prompting recognition, prevention, and treatment efforts that could reduce the impact of delirium and improve quality of life for our older population and their caregivers.

Delirium, defined as an acute decline of cognition and attention, is a common and severe problem for hospitalized older patients, with occurrence rates ranging from 14–56% and hospital mortality rates ranging from 25–33%.1, 2 The development of delirium has been associated with increased morbidity, persistent functional decline, increased nursing time per patient, higher per day hospital costs, increased length of hospital stay, higher rates of nursing home placement and increased mortality.36 Delirium often initiates a cascade of events that can include functional decline, caregiver burden, increased morbidity and mortality, and higher health care costs.35, 710 Delirium in older hospitalized patients is of particular concern because patients aged 65 years and over currently account for more than 48% of all days of hospital care.11

Given the burden associated with delirium both in terms of patient functioning and health care costs, and the fact that a number of interventions have been shown to be effective in preventing or treating delirium,1217 one might think that there would be widespread economic incentives to prevent delirium. For example, hospital administrators should have an incentive to adopt delirium prevention interventions to avoid the clinical and financial consequences of delirium. However, such interventions are implemented infrequently, in part because of erroneous ingrained views about delirium. On one hand, many clinicians and administrators view delirium as an all-but-inevitable part of hospital stays for older patients, while others view delirium as a transient, reversible condition, without long-term sequelae or substantial lasting clinical implications. Contrary to the latter view, recent evidence suggests that delirium has substantial long-term sequelae with significant implications for both health care utilization and costs.26, 8, 10, 1824

While delirium has been increasingly recognized as a common, serious, and potentially preventable source of morbidity and mortality for hospitalized older persons, as well as an important patient safety issue, it receives little attention in terms of resource allocation for clinical care and research. The importance of delirium may continue to be underestimated until its societal and economic impacts are established. Our previous work has advanced the field by developing and validating a widely used delirium instrument (the Confusion Assessment Method),25 identifying delirium risk factors,26, 27 evaluating the prognosis of delirium,4 developing and testing delirium prevention strategies,12, 28 and demonstrating their cost-effectiveness.5, 29 In another study, we determined that patients who develop delirium had a 62% increased risk of mortality and lost an average of 13% of a year of life compared to patients without delirium.6 In addition, delirium prevention – such as with the Hospital Elder Life Program (HELP), a targeted, multicomponent intervention – has been demonstrated to be cost-effective. In the initial controlled trial involving 852 patients, HELP saved an average of $831 per intervention patient for acute hospital costs29 and $9,446 per patient per year in long-term nursing home costs.5 At a dissemination site in a large community hospital, HELP was evaluated using administrative data, and saved $1.25 million per year in 704 patients on one 400-bed unit.30 A follow-up study involving 7,000 patients per year on 6 hospital units resulted in annual savings of $6.9 million ($7.4 million less $440K for costs of program).31 Finally, in the capitated system of Australia, HELP resulted in an annual cost savings of $129,186 (Australian).32 Despite these studies, continued advances in the field are hampered by insufficient recognition of the seriousness and impact of the problem of delirium on a national scale. The lack of attention to delirium is of great concern, given that the problem is common and associated with serious complications, is increasing in magnitude with the aging population, and is potentially preventable.

Hence, understanding and documenting the economic burden of delirium is critical. Information on the costs associated with delirium is relevant to insurers, hospitals, health care systems, and government programs (such as Medicare). There is an opportunity cost associated with treatment of delirium: resources used to treat patients with delirium are then not available for treating other patients. Quantifying these costs may lead to a more efficient allocation of health care resources and improved care for hospitalized patients. Estimates of the health care costs associated with delirium may also increase awareness of delirium among insurers, hospitals, health care systems, and policy-makers, and encourage the implementation of interventions to prevent delirium.

Although a number of studies have examined health care costs related to delirium, many have been limited to specific services (i.e., hospital length of stay, intensive care unit, or nursing home care) or patient subgroups (i.e., mechanically ventilated patients or those undergoing elective surgery) and have been limited by relatively small sample sizes.33, 34 However, two studies have examined more general long-term implications of delirium among a large sample of 841 non-intensive care patients. In the first, patients who experienced delirium (N=109) were found to have a 62% increased risk of mortality within 1 year after discharge and lived on average 274 days, compared to 321 days among patients without delirium, a difference of 13% of a year.6 In the second study,24 total post-discharge one-year health care costs were compared across patients who had delirium during their inpatient stay versus those who did not. Costs included inpatient, outpatient, nursing home, home health, rehabilitation and other services costs. Total costs attributable to delirium ranged from $16,303 (in 2005 dollars) to $64,421 per patient. Following Inouye et al.2 and assuming that delirium complicates hospital stays for 20% of the 11.8 million persons aged 65 and older who are hospitalized each year, these results imply that total direct 1-year health care costs attributable to delirium range from $143 billion to $152 billion nationally.

To put these costs into perspective, one can compare them to costs associated with other conditions. National annual health care costs have been estimated for a number of conditions, including hip fracture ($7 billion),35 non-fatal falls ($19 billion),36 diabetes ($91.8 billion),37 and cardiovascular disease ($257.6 billion).38 While we acknowledge the difficulty and limitations in comparing across conditions due to differences in study methodology, diagnostic overlap, and shared comorbidities, our results suggest that the economic burden of delirium is substantial, even relative to other conditions.

Further research is needed to refine and extend these cost estimates, such as estimating indirect costs and caregiver burden. Already, the work to date highlights the considerable burden of delirium as a serious condition with significant long-term clinical and economic consequences. A call to action in recognition, prevention, and treatment is imperative to reduce the impact of delirium and improve quality of life for our older population and their caregivers.


Grant support In part by Grant #P01AG031720 (SKI) from the National Institute on Aging and Grant # IIRG-08-88738 (SKI) from the Alzheimer's Association.


Conflict of Interest: Dr. Inouye holds the Milton and Shirley F. Levy Family Chair.

Author Contributions: Both authors participated in the design, concept and preparation of the manuscript.


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