Cost of Illness of Alzheimer's Disease
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The Gerontologist Copyright 2003 by The Gerontological Society of America Vol. 43, No. 2, 158–164 Cost of Illness of Alzheimer’s Disease: How Useful Are Current Estimates? Bernard S. Bloom, PhD,1 Nathalie de Pouvourville,2 3 and Walter L. Straus, MD, MPH Downloaded from https://academic.oup.com/gerontologist/article/43/2/158/636148 by guest on 27 September 2021 Purpose: The goal of this literature review was to Cost-of-illness (COI) studies are useful to un- determine the validity and policy relevance of recent derstand the economic burden of illness on patients, estimates from many countries of Alzheimer’s disease families, health care systems, payers, and society. (AD) costs. Design and Methods: We searched They are the economic equivalent of epidemiological surveys of prevalence, incidence, and natural history Medline and other databases for English-language of a disease, and they are typically the initial step in peer-reviewed journals on total, direct, indirect, and an economic evaluation. per case cost of AD that used 1985–2000 data. We The burdens of Alzheimer’s disease (AD) on health adjusted costs of U.S. studies for inflation. We care systems, families, and social services are widely adjusted non-U.S. studies by that country’s medical recognized in the scientific and popular literature. cost inflation rate and purchasing power parity (PPP). Since AD is a disease of senescence, population aging Results: Of 71 studies identified, 21 met all criteria ensures increasing prevalence and intensifying chal- for inclusion. Annual inflation adjusted U.S. total costs lenges for policy makers (Brookmeyer, Gray, & of AD varied from $5.6 billion to $88.3 billion. AD Kawas, 1998; Jorm, Korten, & Henderson, 1987; total per case (direct and indirect) costs varied from Lobo et al., 2000; Ritchie, Kildea, & Robine, 1992; $1,500 to $91,000; indirect/family costs varied Trabucchi, 1999). Current U.S. estimates of preva- from $3,700 to $21,000. Among non-U.S. studies, lence range from 1.09 to 4.58 million people, affecting between 2.7% and 11.2% of the population aged older AD annual adjusted per case costs varied from PPP than 65 years (Brookmeyer et al., 1998; Trabucchi, $2,300 to PPP $30,000. Cost variation was due to 1999). Prevalence is estimated to increase nearly four- diverse study methods, data sources, services fold to between 4.2 and 15.4 million whereas annual included, and lack of clear differentiation between incidence is expected to rise from 360,000 new cases in cost of AD and cost of caring for people with 1997 to 1.14 million in 2047 (Brookmeyer et al.). As AD. Implications: The cost of AD is high, although prevalence increases, so will expenditures for this reliable estimates are not available. Costs are likely to chronic and progressive disease for multiple family, rise given expected demographic shifts in all coun- medical, social, and community resources (Ernst & tries. The widely variable cost estimates call into Hay, 1997; Meek, McKeithan, & Schumock, 1998). question the real costs of Alzheimer’s disease and However, reported annual U.S. estimates of AD cost their applicability to policy initiatives. vary five-fold, from $20 billion to $100 billion (Ernst & Hay, 1994; Leon, Cheng, & Neumann, 1998; Key Words: Alzheimer’s disease, Dementia, Cost, Menzin, Lang, Friedman, Neumann, & Cummings, Economics 1999; Rice et al., 1993; Schumock, 1998). A majority of costs are for long-term care, reduced function, and family care giving (Ernst & Hay, 1994, 1997; Max, Webber, & Fox, 1995; Rice et al., 1993). Funded, in part, by a grant from Aetna/US Healthcare Foundation. Most people with AD are elderly and often have We acknowledge the able assistance of Kathryn A. Kvam, Nicolas multiple high-cost diagnoses. Thus, allocating pre- Renaud, and Suzanne Vogel. cisely direct, indirect, and nonmedical costs of AD Address correspondence to Bernard S. Bloom, University of Pennsylvania, Department of Medicine, Division of Geriatrics, 3615 across all diagnoses for the same person is particu- Chestnut Street, Philadelphia, PA 19104-2676. E-mail: bsbloom@ larly difficult. This is the problem of joint product, mail.med.upenn.edu 1Department of Medicine, Division of Geriatrics, University of wherein it is difficult to attribute specific medical Pennsylvania, Philadelphia. services and their costs, in part or in whole, to each 2Universite´ de Paris V, Hoˆpital Cochin, Paris, France. 3Outcomes Research and Management, Merck & Company, West diagnosis. Accurate attribution is especially prob- Point, PA. lematic in estimating AD costs as there are few, only 158 The Gerontologist modestly efficacious medical treatments with mainly currency, adjusted for their inflation rates (1982– short-term effects (Winblad & Wimo, 1999). 1984 5 100). Further, we adjusted costs across The goal of this study was to examine the countries to U.S. dollars by purchasing power parity usefulness of published cost-of-illness estimates of (PPP) for the year of each country’s data (World AD. Accurate cost data are fundamental for in- Bank Group, 2000). PPP is a technique that allows formed policy and clinical decisions by patients, for accurate comparisons across countries of income physicians, and payers to meet clinical, quality-of- and cost of purchasing goods and services. For life, and economic objectives. example, a metric can be the number of hours a person must work to purchase a kilowatt of electricity or an ambulatory physician visit. PPP is accepted as the most accurate way to measure the Methods ability of the currency of one country to purchase We searched Medline, Econlit, and related com- goods and services in other countries. puterized databases from 1 January 1985 through 31 Downloaded from https://academic.oup.com/gerontologist/article/43/2/158/636148 by guest on 27 September 2021 December 2000, by using the following search terms: Alzheimer’s, dementia, economics, and cost (as well Results as all variations). Visual search of bibliographies of We identified 71 studies, 46 from the United States published articles identified additional studies not and 25 from other countries. We excluded 50 studies; found by Medline searches. Three reviewers in- 29 did not meet entry criteria—eight had population dependently abstracted each study. Disagreements samples less than 100 patients, 4 had too few cost were resolved among the reviewers. Studies had to categories (e.g., only ambulatory medical costs), 8 meet all of the following criteria for inclusion: used data from before 1985, and 1 showed savings only. Thus, we included 21 studies for review. 1. Most study patients with dementia were diagnosed with AD. 2. Cost data were from 1 January 1985 through Definition of Alzheimer’s Disease 31 December 2000. 3. Studies had to enroll at least 100 patients. We used each study’s authors’ definition of AD. 4. Study had to be published in an English- Fourteen studies included all types of dementia in their language peer-reviewed journal. analysis. Four studies used secondary sources like paid claims data and relied on ICD recorded coding We compared results and conclusions of all studies, (Gutterman, Markowitcz, Lewis, & Fillit 1999; examining similarities and differences in study Menzin et al., 1999; Taylor & Sloan, 2000; Weiner, methods, data collected, cost-calculation processes, Powe, Weller, Shaffer, & Anderson, 1998). Four sources used, and cost estimates. We collected studies relied on the Mini-Mental State Examination epidemiological estimates of AD prevalence and (Hux et al., 1998; Østbye & Crosse, 1994; Rice et al., incidence. We collected or calculated from each study 1993; Soueˆtre, Thwaites, & Yeardley, 1999), two used annual total and costs per person with AD (per case National Institute of Neurological and Communica- costs); we calculated incremental costs of AD for tive Diseases and Stroke criteria (Kronborg-Andersen controlled studies. Costs attributable to AD, or any et al., 1999; Leon et al., 1998), and one used results of diagnosis, are difficult to estimate in the face of a randomized control trial (O’Brien et al., 1999). Five multiple diagnosis. For example, it is nearly impos- studies gave no specific source of disease definition. sible to separate the components of an ambulatory Adjustment for AD severity was made in 10 studies visit or an inpatient stay into those costs specifically (Ernst & Hay, 1997; Kinosian et al., 2000; Kronborg- attributable to each diagnosis for the individual Andersen et al., 1999; Leon et al., 1998; Max et al., patient. The best alternative is to estimate incremental 1995; Rice et al., 1993; O’Brien et al., 1999; Schneider, AD costs by examining in two comparable cohorts, Kavanaugh, Knapp, Beecham, & Netten, 1993; one with and one without AD, all costs of care. The Soˆuetre et al., 1999; Taylor & Sloan, 2000). Five differences (incremental) in costs can be defined as studies adjusted for comorbidity (Gutterman et al., those of AD. We found two types of controlled 1999; Kavanaugh & Knapp, 1999; Kinosian et al., studies—(a) those that measured costs in populations 2000; Leon et al., 1998; Menzin et al., 1999). with and without AD, and (b) those that compared costs of care for people with AD living in an Medical and Cost Data Collected institution to people with AD living in the community. For all studies, the total number of people with There was wide variability of cost data items AD was the denominator. For U.S. studies, we across studies. Additionally, service definitions were adjusted costs by sector specific (e.g., hospital, not uniform. For example, hospital costs may have pharmaceuticals) medical care price indices, 1982– included, individually or in varying combinations, 1984 5 100 (U.S. Bureau of the Census, 1999). Non- acute, short-term, long-term, mental, and/or rehabil- U.S. study costs were expressed in that country’s itation inpatient care. Indirect costs for activities like Vol.