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Patient Dependence, Function, and Changes in Cost of Care in

Alzheimer’s Disease

Carolyn W. ZhuJJP VA Medical Center, Mount Sinai School of Medicine

Academy HealthJune 10, 2008

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Collaborators

• Christopher Liebman Elan Pharmaceuticals• Trent McLaughlin Elan Pharmaceuticals• Nickolas Scarmeas Columbia University Medical Center• Marilyn Albert Johns Hopkins University • Jason Brandt Johns Hopkins University• Deborah Blacker Harvard Medical School• Mary Sano Mount Sinai School of Medicine• Yaakov Stern Columbia University Medical Center

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Background• Alzheimer’s disease (AD) is characterized by

impairment in cognition, function, and behavior

• Cost of care for patients with AD are significantly associated with functional impairment

• Functional impairment may not fully represent patients’ overall dependence on other individuals

• Functional impairment provides partial explanation of variation in AD related costs

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Background (cont.)

• Dependence Scale (DS) was developed to directly measure the amount of assistance AD patients need

• DS measured related but distinct aspects of disability in AD

• Information on the relationship between DS and healthcare cost is limited

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Objectives

• To examine the relationship between patients’ dependence and function on cost of care at baseline and longitudinally

• To compare strengths of their relationships with different cost components

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Dependence Scale Sample QuestionsDependence Scale Sample Questions

A. Does the patient need reminders or advice to manage chores, do shopping, cooking, play games, or handle money?

B. Does the patient need help to remember important things such as appointments, recent events, or names of family or friends?

L. Does the patient wear a diaper or a catheter?

M. Does the patient need to be tube fed?

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Methods: Sample• Design

– Prospective study with up to 7 years of annual follow-up

• Setting

– Three University-based AD centers in the US

• Subjects– Met DSM-III-R criteria for primary degenerative dementia of the

Alzheimer type and NINDS-ADRDA criteria for probable AD

– Modified Mini-Mental State Examination (mMMS) ≥30 at enrollment

– Visits during which patient was living in nursing home excluded

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Methods: Dependent Variables• Direct medical cost

- Hospitalizations, assistive devices, outpatient tests and procedures, medications

• Direct non-medical cost- Home health aides, respite care, adult daycare

• Informal cost- Cost of informal caregivers’ time for basic and instrumental

activities of daily living (BADL and IADL) - Up to three caregivers’ time included

• Costs adjusted to 2005 constant dollars

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Methods: Independent Variables• Main independent variables

– Dependence: Dependence Scale (DS)

– Function: Blessed Dementia Rating Scale (BDRS)

• Other clinical variables

– Mini-Mental State Examination (MMSE)

– Presence of psychotic symptoms, behavioral problems, depressive symptoms, extrapyramidal signs

– Number of comorbidities

• Demographic variables

– age, sex, race/ethnicity, education, site

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Methods: AnalysisMethods: Analysis

• Baseline analysis: Generalized linear models with gamma distribution and identity link

• Longitudinal analysis: Generalized linear mixed models

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Methods: Analysis (cont.)Methods: Analysis (cont.)

• Two sets of models estimated for each analysis

- Full model: DS, BDRS, all other covariates

- Trimmed model: DS, BDRS, demographics, site

• Varied wage rates

- National average hourly earnings for all private industries

- National average wage for home health aides

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% female 58

Age, mean (sd) 76 (8)

% White 96

Years of schooling, mean (sd) 14 (3)

% Married 67

Results: Baseline DemographicsResults: Baseline Demographics

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Results: Baseline Clinical CharacteristicsResults: Baseline Clinical Characteristics

Dependence Scale (0-15), mean (sd) 5.1 (2.3)

Blessed Dementia Rating Scale (0-17), mean (sd) 3.5 (2.1)

Mini-Mental State Examination (0-30), mean (sd) 22.1 (3.6)

# Comorbidities, mean (sd) 0.8 (0.9)

% Behavior problems 41.6

% Psychotic symptoms 30.2

% Depressive symptoms 20.5

% Extrapyramidal signs 14.5

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Results: Baseline Healthcare UseResults: Baseline Healthcare Use

Number of hospitalizations, mean (sd) 0.3 (0.6)

Number of outpatient treatments/procedures, mean (sd)

2.0 (2.1)

Number of assistive devices, mean (sd) 1.2 (1.1)

Number of medications, mean (sd) 3.8 (1.5)

Informal hours per week, mean (sd) 20.7 (24.0)

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Results: Medical and Non-medical Results: Medical and Non-medical Cost by Dependence ScaleCost by Dependence Scale

Figure 1. Medical and Non-medical Costs by Dependence Scale Score

$0

$5,000

$10,000

$15,000

$20,000

$25,000

$30,000

$35,000

$40,000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Dependence Scale

Medical Care Non-medical Care

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Results: Informal Caregiving Time Results: Informal Caregiving Time by Dependence Scaleby Dependence Scale

Figure 2. Informal Caregiving Hours by Dependence Scale Score

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Dependence Scale

Hours per

Week

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Results: Baseline AnalysisResults: Baseline Analysis

* p<0.05

Direct Medical Costcoef. (se)

Informal Costcoef. (se)

DS $298 (408) $1,690 (749)*

BDRS $1,406 (702)* $1,941 (1,458)

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Results: Longitudinal AnalysisResults: Longitudinal Analysis

** p<0.01 * p<0.05

Direct Medical Cost

Direct Non-medical Cost

Informal Caregiving

Time

DS 5.7%** 10.5%* 4.1%**

BDRS 7.6%* 3.8%** 8.7%**

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ConclusionsConclusions• Both dependence and functional impairment are

significantly associated with higher costs of care

• Dependence and function relate differently to different components of costs

• Small changes in dependence and function are related to large changes in healthcare costs

• Relationship observed at baseline is consistent over time

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LimitationsLimitations

• Sample may represent a nonrandom sample of AD patients in the community

• Estimated costs are costs associated with caring for patients with AD, not incremental costs due to AD

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ImplicationsImplications

• Dependence and function provide unique information in explaining variations in cost of care in AD

• Interventions that enhance patient independence (or delay patients moving to a higher level of dependence) may be associated with cost savings