1
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
2
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
3
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
4
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
5
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
6
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?
7
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
8
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
9
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
10
Methods: AnalysisMethods: Analysis
• Baseline analysis: Generalized linear models with gamma distribution and identity link
• Longitudinal analysis: Generalized linear mixed models
11
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
12
% female 58
Age, mean (sd) 76 (8)
% White 96
Years of schooling, mean (sd) 14 (3)
% Married 67
Results: Baseline DemographicsResults: Baseline Demographics
13
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
14
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)
15
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
16
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
17
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)
18
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%**
19
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
20
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