The Dependence Scale for Alzheimer’s Disease

By Jaimie Lazare

The Dependence Scale, a questionnaire that serves as a valuable tool, measures the amount of assistance needed by Alzheimer’s disease patients.

Alzheimer’s disease (AD) is marked by progressive cognitive decline that encroaches on the ability of patients to carry out even the simplest tasks. Such cognitive and functional decline eventually requires the assistance of a caregiver to help with activities of daily living. The Dependence Scale (DS) is a research tool that’s used to assess how much assistance AD patients require from their caregivers.

At some point in our lives, we’ve experienced the awkwardness of forgetting someone’s name or the frustration of forgetting where we’ve placed items such as our car keys. Among older adults, discovering whether these lapses in memory are simply attributable to old age or portents to neurological conditions like Alzheimer’s disease (AD) is daunting. AD is riddled with cognitive, functional, and behavioral changes that profoundly impact the quality of patients’ lives—and the lives of their caregivers. New research presented at the Alzheimer’s Association International Conference (AAIC) used the Dependence Scale (DS) to hone in on dependency in AD, its effect on caregivers, and its financial impact.   

Overall, the studies presented at the AAIC found the following to be associated with the DS:

• It shows good construct validity in relating the level of patients’ dependence to their need for institutionalization. (Almost all patients with a DS score greater than 12 were institutionalized.)

• It shows AD patients experienced greater dependence and use of resources than patients with mild cognitive impairment.

• It has a strong correlation between dependency and deterioration in clinical measures such as cognition, function, and behavior.

• It demonstrates increases in direct and indirect costs as dependency increased.

What Is the Dependence Scale?
The Dependence Scale is a 13-item questionnaire completed by an AD patient’s primary caregiver. It measures the amount of assistance needed by the patient but not necessarily how much assistance he or she actually receives, says Joel Bobula, senior director of Global Health Economics & Outcomes Research at Pfizer in New York. The DS is a series of yes or no questions such as: Does the patient need reminders or advice to manage chores, shop, cook, play games, or handle money? Does the patient need to be escorted when outside? Does the patient wear a diaper or a catheter? The DS score ranges from zero, meaning not dependent at all, to 15, which would indicate a patient is fully dependent, he says.

The DS attempts to correlate functional loss and dependence with the reasons that lead to people ending up in institutions, says Roy W. Jones, BSc, MB, FRCP, DipPharmMed, director of the Research Institute for the Care of Older People in Bath, England. “For instance, the reason someone ended up in an institution isn’t necessarily because they can’t make a cup of tea or that they can’t do their own shopping but because their decline in function is creating more dependence on other people,” he says.

Research shows that functional and noncognitive symptoms correlate poorly with cognitive symptoms, which demonstrates the value of utilizing the DS to assess functional decline and loss of independence among AD patients.1

Cognition is an important issue in dementia. But it involves numerous components, such as memory, language, attention, and visuospatial factors. It isn’t a direct marker for activities of daily living or dependence that rely on a more complex range of issues, Jones notes. “No one gets admitted to a nursing home because they can't spell ‘world’ backwards [a task on the Mini-Mental State Examination],” he says. “Many of the cognitive tests are quite poor at assessing executive function, which is necessary for carrying out complex activities like driving or cooking a meal, and these are areas that will contribute to dependence and functional status.”

Although there is no perfect scale to assess the totality of a patient’s cognition, the DS does seem to be a better way of trying to capture the relationship between functional decline and patient dependence on caregivers, Jones says. 

He notes that dependency is about the relationship between the patient and the family—assessing how much support the patient needs and identifying whether the patient can be left alone. Interventions such as drug treatments do have an impact on dependence, and data suggest that AD drugs help to delay entering a nursing home, he says. 

A recent study showed that prescribing cholinesterase inhibitors such as Aricept was associated with delays in institutionalizing AD patients.2 

Anticipate Care Needs and Estimate Costs
One of the AAIC’s presentations focused on understanding how to implement the DS in clinical practice. Christopher Leibman, head senior director of health economics/market access at Janssen Alzheimer Immunotherapy in San Francisco, says, “Is there a way that people could answer these questions and then a clinician could look at them and say, ‘I see what the needs and service requirements of this patient are’? I think from what we’ve seen from this research, we feel confident that this scale does a better job of helping patients and families prepare for their future than a scale that measures strictly on quality of life.”

Leibman notes, “The focus of this scale at this point is on research to support its validation and its use both in clinical trials and potentially in clinical practice.” 

The DS is focused on measuring AD in terms of the resources used in caring for these patients. Clinicians focus more on measures such as cognition, function, and behavior, Bobula says. 

One study reported that a one-point increase in the DS was associated with 5.7%, 10.5%, and 4.1% increases in direct medical costs, direct nonmedical costs, and caregiver time, respectively.3

“So not only are we tracking what the clinician measures with the Dependence Scale, but we’re also tracking healthcare costs and even indirect costs, such as caregiver time,” Bobula says. 

Leibman adds that the research is focused on evaluating questions such as: When should a home health aide be hired? When will there be an increase in caregiver needs and caregiver time? When will things like Meals on Wheels be brought in? “We’re going to continue to do more and more research around trying to establish how a physician could use it. So we’re exploring the best method to have and use in a clinical practice setting,” he says.

Bobula notes that research provides information on the direct medical costs, direct nonmedical costs, and informal caregiver costs at each stage of AD using the DS. 

For example, low levels of dependency in AD patients have been associated with $5,000 in direct medical care costs, but high levels of dependency increase this amount about three to four times.3 Researchers evaluating patient dependence and home health aide use found that three items on the DS significantly predicted the need for an aide: the patient’s need for household chores to be done for him or her; the need to be watched or kept company when awake; and the need to be escorted when outside. Such information can be used by practitioners to advise both the patient and the caregiver about the appropriateness of in-home care in order to delay nursing home placement that is not only costly but is also associated with higher mortality rates.4

The goal is using this scale to manage care, anticipate costs, and potentially help patients and their families regarding what to expect next, Liebman says.

— Jaimie Lazare is a freelance writer based in Brooklyn, N.Y.

References

1. Brickman AM, Riba A, Bell K, et al. Longitudinal assessment of patient dependence in Alzheimer disease. Arch Neurol. 2002;59(8):1304-1308.

2. Salib E, Thompson J. Use of anti-dementia drugs and delayed care home placement: An observational study. Psychiatrist. 2011;35(10):384-388.

3. Zhu CW, Leibman C, McLaughlin T, et al. Patient dependence and longitudinal changes in costs of care in Alzheimer’s disease. Dement Geriatr Cogn Disord. 2008;26(5):416-423.

4. Scherer RK, Scarmeas N, Brandt J, Blacker D, Albert MS, Stern Y. The relation of patient dependence to home health aide use in Alzheimer's disease. J Gerontol A Biol Sci Med Sci. 2008;63(9):1005-1009.