1 The valuation of disease-specific questionnaires for QALY analysis To rescue data in absence of...
-
Upload
cuthbert-hood -
Category
Documents
-
view
216 -
download
2
Transcript of 1 The valuation of disease-specific questionnaires for QALY analysis To rescue data in absence of...
1
The valuation of disease-specific questionnaires for QALY analysis
To rescue data in absence of an utility measure Growth hormone deficiency in adults
To increase sensitivity Benign Prostatic Hyperplasia (BPH)
2
Mapping
Trying ‘to map’ disease characteristics on EQ-5D etc. Nord E. Cost-utility analysis of
Melphalan plus Prednisone with or without Interferon Alfa-2b in newly diagnosed multiple myeloma. Pharmacoeconomics 1997;12:89-103.
Can be done behind the desk Very quick…
Very dirty…
A low face validity…
3
Mapping DALY style
4
QoL-AGHDA
Quality of Life Adult Growth Hormone Deficiency Assessment 25 yes/no items
Internet panel N = 1075
Both AGDHA and EQ-5D
5
From AGDHA to utilities (QALY)
EQ-5D: 5 dimensions AGHDA: 25 dimensions
UtilityAlgorithm Sum
Score
Utilities Total scoreRegression
Regression
6
Regression Dutch AGHDA sum score on EQ-5D
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20 25
AGHDA
EQ
-5D
NL
EQ-5D = 0.980 - 0.0198 x AGHDAR2 = .344
EQ-5D-3L versus EQ-5D-5l
Zet bij iedere groep in de lijst hieronder een kruisje in het hokje achter de zin die het best past bij uw eigen gezondheidstoestand vandaag. Mobiliteit
Ik heb geen problemen met lopen
Ik heb een beetje problemen met lopen
Ik heb matige problemen met lopen
Ik heb ernstige problemen met lopen
Ik ben niet in staat niet om te lopen
Zelfzorg
Ik heb geen problemen met mijzelf wassen of aankleden
Ik heb een beetje problemen met mijzelf wassen of aankleden
Ik heb matige problemen met mijzelf wassen of aankleden
Ik heb ernstige problemen met mijzelf wassen of aankleden
Ik ben niet in staat mijzelf te wassen of aan te kleden
Dagelijkse activiteiten (bijv. werk, studie, huishouden,
gezins- en vrijetijdsactiviteiten)
Ik heb geen problemen met mijn dagelijkse activiteiten
Ik heb een beetje problemen met mijn dagelijkse activiteiten
Ik heb matige problemen met mijn dagelijkse activiteiten
Ik heb ernstige problemen met mijn dagelijkse activiteiten
Ik ben niet in staat mijn dagelijkse activiteiten uit te voeren
Pijn/ongemak
Ik heb geen pijn of ongemak
Ik heb een beetje pijn of ongemak
Ik heb matige pijn of ongemak
Ik heb ernstige pijn of ongemak
Ik heb extreme pijn of ongemak
Angst/somberheid
Ik ben niet angstig of somber
Ik ben een beetje angstig of somber
Ik ben matig angstig of somber
Ik ben erg angstig of somber
Ik ben extreem angstig of somber
Zet bij iedere groep in de lijst hieronder een kruisje in het hokje achter de zin die het best past bij uw eigen gezondheidstoestand vandaag. Mobiliteit
Ik heb geen problemen met lopen
Ik heb enige problemen met lopen
Ik ben bedlegerig
Zelfzorg
Ik heb geen problemen om mijzelf te wassen of aan te kleden
Ik heb enige problemen om mijzelf te wassen of aan te kleden
Ik ben niet in staat mijzelf te wassen of aan te kleden
Dagelijkse activiteiten (bijv. werk, studie, huishouden,
gezins- en vrijetijdsactiviteiten)
Ik heb geen problemen met mijn dagelijkse activiteiten
Ik heb enige problemen met mijn dagelijkse activiteiten
Ik ben niet in staat mijn dagelijkse activiteiten uit te voeren
Pijn/klachten
Ik heb geen pijn of andere klachten
Ik heb matige pijn of andere klachten
Ik heb zeer ernstige pijn of andere klachten
Stemming
Ik ben niet angstig of somber
Ik ben matig angstig of somber
Ik ben erg angstig of somber
Cross walk
8
Validation
9
Calculation
10
11
The AGHDA has generic features… AGHDA
I have to struggle to finish jobs
I feel a strong need to sleep during the day
I often feel lonely even when I am with other people
EQ-5D I have some problems with performing my usual activities
I am moderate anxious or depressed
Correlation makes sense AGHDASUM
AGHDASUM
24.00
22.00
20.00
18.00
16.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
.00
Pe
rce
nt
30
20
10
0
12
But what if the measure has little generic features?
International Symptom Prostate Score (IPSS) BPH
Enlargement of the prostate Causes voiding problems in elderly men
• Difficulties to pee 7 questions: How often have you
had to push or strain to begin urination? had a sensation of not emptying your bladder completely? had to urinate again less than two hours after you finished urinating?
found you stopped and started again several times when you urinated?
you find it difficult to postpone urination? had a weak urinary stream? How many times did you most typically get up to urinate from the time
you went to bed at night until the time you got up in the morning?
13
Does the EQ-5D make sense in BPH? MOBILITY
I have no problems in walking about I have some……. I am confined to bed
SELF-CARE I have no problems with self-care I have some problems….. I am unable…
USUAL ACTIVITIES I have no problems with performing my usual
activities I have some problems… I am unable….
PAIN/DISCOMFORT I have no pain or discomfort I have moderate ….. I have extreme……..
ANXIETY/DEPRESSION I am not anxious or depressed I am moderately…….. I am extremely…..
Not sensitive fo
r BPH
14
Can we convert the IPSS outcomes into utilities?
Attribute TTO values to the IPSS health states Problem: IPSS has 279.936 health states
7 items, 6 answer levels = 6x6x6x6x6x6x6 = 279.936 health states
Too many to value with TTO
Reduce number of health states Reduce items
• Factor analysis
Reduce answer levels
• Combine answer levels
15
Factor analysis on patients IPSS responses N = 1414
Two main factors Obstructive (alpha= 0.8018) Irritative (alpha= 0.7165)
• Confirmed in literature
Factors divided in 3 levels Number of health states reduced to 33 = 9
Can be valued directly
TTO General public, representative for gender/age (N=170)
Reduce number of health states
16
Exercise
Value the 9 health states of the reduced IPSS Tests feasibility: can it be done?
Compare values with earlier research Test reliability: can we repeat the observation?
• Scientific prove (observation is independent of examination)
• Do different groups of people have different values
17
QALY weights for BPH
almost always
sometimes
seldom/never
almost alwayssometimes
seldom/never
0,5
0,55
0,6
0,65
0,7
0,75
0,8
0,85
0,9
0,95
1
utilities (TTO)
obstructive
irritative
18
0.00.10.20.30.40.50.60.70.80.91.0
11 12 13 21 22 23 13 23 33
Health states IPSS
TT
O
ISPOR 2003 Population
Comparing ISPOR 2003 with population
19
How to come to these values?
Obstructive score Sum (IPSS1 + IPSS2 +IPSS4 + IPSS6)
Irritative score Sum (IPSS3 + IPSS5 +IPSS7)
Answer levels:
Domain score Level
Obstructive ( <= 4) Obstructive 1
( >= 5 & <= 16) Obstructive 2
( >= 17) Obstructive 3
Irritative (<= 3) Irritative 1
( >= 4 & <= 9) Irritative 2
( >= 10) Irritative 3
irritative
1.00 .97 .95 1
.97 .94 .92 2
.92 .90 .87 3
1 2 3
Obstructive
As example: obstructive 1 and irritative 2 = uti 1_2
Quality of life values:
20
Treatment effect
0,9
0,91
0,92
0,93
0,94
0,95
0,96
0,97
0,98
baseline follow up
uti
litie
s
surgery (n= 144) alpha-blockers (n=33)
finasteride (n=35) watchful waiting (n=159)
Disease specific utilities are not on a generic scale
Generic top anchor absence of any impairment
Specific top anchor absence of specific impairment
Co morbidity might still be present
No disease specific problems
All disease specific complains
Death
Healthy
Disease specific utilities are a subscale of a generic scale
Rescaling necessary
No disease specific problems
All disease specific complains
Death
Healthy
23
Raw disease specific trade-off ten to overestimated gains
Value of life years “traded off” in TTO differently Healthy subject: 1 life year is 1.0 QALY
Sick subject: 1 life year is 0.8 QALY
Life years of healthy persons are more worth than those of sick
Disutility is proportional 20% trade off at 1.00: disutility = 0.20
20% trade off at 0.80: disutility = 0.16
20% trade off at 0.60: disutility = 0.12
24
Specific utilities should be corrected for average morbidity Solution: multiplicative model Multiply disease specific value with average value Values have to be multiplied by average value for age
group. For instance in IPSS
• male age 55-64: overall QoL utility: 0.81
• Most severe BPH: 0.87
• Male age 55-64 with most severe BPH: 0.81 x 0.87 = .7047
Maximum gain reduces from Raw score 1.00 - 0.87 = 0.13
Adjust score 0.81 - 0.70 = 0.11
15 % reduction
25
Rue of thumb
Overestimated CE-ration by 15% using specific utilities Proposed by Fryback & Lawrence, MDM 1997
• For not completely the same problem…
• …for own health states, not imaginable health states
26
We validated the IPSS for the use in economic appraisal Now, IPSS has QALY-weights
New and already published research can be converted into QALYs
Advantage use specific QALYs measures High sensitive disease specific measures for QALY-analysis
Rescuing data
Disadvantages Not directly compatible with generic utilities
± 15 % correction needed in disease specific
Conclusion