![Page 1: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/1.jpg)
Dintsios CM / Scheibler FF / Janssen I / Gerber A / Finger R
HTAi, Bilbao, June 25th 2012
How Glaucoma Patients Assess Different Aspects of Their Treatment?
An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)
![Page 2: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/2.jpg)
Rationale: Why calculate weights?
Patients weight different treatment aspects according to their preferences Patients’ preferences
These aspects may serve as patient-relevant measures (endpoints) in HTA Patients’ involvement
By weighting treatment aspects prioritization is based on patients’ views Legitimating
In benefit assessments or cost-effectiveness analyses the derived weights can be used for the aggregation of multiple (composite) endpoints Endpoint aggregation
…
Weighting treatment aspects
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 2
![Page 3: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/3.jpg)
Rationale: Why AHP?
Patient preferences as a basis for weighting treatment aspects
elicit preferences via AHP AHP is one method – others are available, e.g.
Conjoint Ananlysis
AHP
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 3
![Page 4: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/4.jpg)
Objective of the AHP
To weigh the different aspects of glaucoma treatment by eliciting the preferences of patients with the AHP-procedure.
I.e. to estimate the „relative importance“ of treatment aspects, especially importance to patients
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 4
![Page 5: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/5.jpg)
The mathematician Thomas L. SAATY developed the AHP procedure in the early 1970th as a technique to solve multicriteria decision problems
How the procedure works: Decision issues are structured hierarchically into
different levels of criteria / alternatives.
Background
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 5
![Page 6: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/6.jpg)
Hierarchical Structure of the AHP
Decision Problem (which car do I want?)
Criterium 1(e.g. colour)
Criterium 2(e.g. gasoline consumption)
... Criterium n
Criterium 1.1 ...
Alternative 1(Peugeot 206)
Alternative n...Alternative 2
(Golf)
...
Criterion 1Criterion 2
Criterion n
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 6
![Page 7: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/7.jpg)
How the AHP works
Pairwise comparisons of criteria are used to elicit the relative importance of one criterion in comparison to the others
Mathematical procedure: based on matrices of pairwise comparisons weights are calculated for each criterion with the help of the „Eigenvector“-method
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 7
![Page 8: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/8.jpg)
AHP scale used in pairwise comparisons
How much more important is criterion A in comparison to criterion B?
13579 3 5 7 9
A BEqual importance
1 - equally important3 - slightly more important5 - more important7 - much more important9 - extremely more important
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 8
![Page 9: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/9.jpg)
AHP matrix of pairwise comparisons
A B C
B
A
C
1 1/5
1
2
6
1
5
1/2 1/6
AHP Matrix
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 9
![Page 10: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/10.jpg)
Mathematical conditions on the AHP structure
1) Completeness of criteria a complete set of criteria should be assessed
2) Independence of preference information at the different levels of hierarchy
3) Independence of criteria should be disjunct, exclude each other
4) Scale should be a relative scale preferences measured on a common relative scale
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 10
![Page 11: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/11.jpg)
The preferences of individuals should correspond to the following prerequisites
1) Reciprocity if A is 3 times more important than B, then B is 1/3 as important
as A
2) Transitivity if A >B and B>C then A>C
3) Consistency resulting from reciprocity and transitivity
Prerequisites
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 11
![Page 12: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/12.jpg)
Pairwise comparison matrix A; relative weights w1, w2 und w3 of the compared elements are known
Multiply matrix A with the vector W of the weights:
This equates to the multiplication of the respective weight with the number of the compared elements n
3 x w1
3 x w2
3 x w3
Calculation of the right “Eigenvector” (I)
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 12
![Page 13: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/13.jpg)
This relation is described by the following equation:
A x W = n x W
with A = pairwise comparison matrix,
W = vector of the weights, n = compared elements
In Matrix Algebra: W = right „Eigenvector“ n = Eigen-value of matrix A
In reality W is unknown and has to be approximated by a regression analysis approach
Calculation of the right “Eigenvector” (II)
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 13
![Page 14: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/14.jpg)
This transforms the equation to:
A* x W* = λmax x W*
with A* = pairwise comparison matrix, W* = right Eigenvector of matrix A, λmax = maximal Eigen-value of matrix A*
Basic assumption of AHP: the calculated right Eigenvector of matrix A equates approximately the vector of the relative weights
Calculation of the right “Eigenvector” (III)
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 14
![Page 15: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/15.jpg)
Is measured by the so called Consistency Ratio (CR)
Is checking for the „logic“ of the particular pairwise comparison, (i. e. how consistent is the respective pairwise comparison with regard to all the other pairwise comparisons)
According to SAATY a CR ≤ 0,1 is accepted and allows for the conclusion that the weights are derived on a consistent basis
Inconsistency
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 15
![Page 16: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/16.jpg)
Inconsistent judgments
A > B > C > A
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 16
![Page 17: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/17.jpg)
N = 7 Pretest => Language abilities, Cognition, Proxies
N = 25 Patients
Setting: Ophthalmology ambulance at University of Bonn
Glaucoma patients: different manifestations and severities
AHP-Questionnaire
Elicitation of utilities with EQ5D – VAS
Stratification according to these utilities
Patient sample
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 17
![Page 18: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/18.jpg)
N = 25 Study; 68,3±13,3 years; €8 17; first diagnosis 1 – � �21 years
Glaucoma
Primary chronic wide-angle glaucoma 55%
Narrow-angle (congestive) glaucoma 9%
Wide-angle glaucoma with narrow-angle component 9%
Normal-tension glaucoma 9%
Suspected glaucoma 18%
visual acuity bad eye 0,59 ± 0,33
Tensio RE 17,2 ± 6,2; Tensio LE 18,1 ± 4,7
Glaucoma management +/- 82%/18%
Patients’ characteristics
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 18
![Page 19: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/19.jpg)
Reading and seeing detail
Peripheral vision
Darkness and glare
Autonomy subdivided in:
household chores
outdoor mobility
Treatment-related patient’s burden
Side effects
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 19
Assessed aspects
![Page 20: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/20.jpg)
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 20
Example: Questionnaire different side effects
![Page 21: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/21.jpg)
21
EQ-5D VAS
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 21
![Page 22: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/22.jpg)
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 22
![Page 23: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/23.jpg)
weight, mean, sd, CI95%
Reading and seeing detail 0.229, 0.212 ± 0.123, 0.161 -
0.263
Peripheral vision 0.089, 0.085 ± 0.058, 0.061 -
0.109
Darkness and glare 0.153, 0.165 ± 0.111, 0.119 -
0.211
Autonomy subdivided in: 0.394, 0.371 ± 0.145, 0.311 -
0.431
household chores 0.239, 0.275 ± 0.258,
0.168 - 0.381
outdoor mobility 0.761, 0.725 ± 0.258, 0.619 -
0.832
Treatment-related burden 0.047, 0.052 ± 0.050, 0.027 -
0.076
Side effects 0.088, 0.115 ± 0.131, 0.060 - 0.168
Utilities EQ-5D vs VAS (82.76 ± 22.21 vs. 65.64 ± 19.95, p =
0.003)
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 23
Results
![Page 24: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/24.jpg)
U > 80 (N = 7)
U < 65 (N = 11)
© Dintsios | HTAi | Bilbao, June 25 th2012 | Glaucoma patients’ preferences
Page 24
Stratified population comparison
AutonomyReading detailsDarkness & GlarePeripheral visionSide effectsTreatment burden
AutonomyReading detailsDarkness & GlarePeripheral visionSide effectsTreatment burden
AutonomyReading detailsDarkness & GlarePeripheral visionSide effectsTreatment burden
![Page 25: How Glaucoma Patients Assess Different Aspects of Their Treatment? An Elicitation of Patients’ Preferences by Analytic Hierarchy Process (AHP)](https://reader035.vdocuments.net/reader035/viewer/2022062617/54bdd8d44a7959e9508b4580/html5/thumbnails/25.jpg)
Thank you!