Introduc o o ti n to

QALYs and Preferen

Measurement in CEA

Patsi Sinnott, PT, PhD, MPH

HERC Economics Course HERC Economics Course

Dec. 14, 2011
O i verv ew

 Brief review CEA and Outcomes Estimating QALYs in CEA Pref / ili i ference/utility measurement in C Most frequently used preference 

measurement systems

 Guidelines on selecting measures Guidelines on selecting measures

Health Economics Resource Center
Th Ch ll i CEA The Ch

allenge 

in CEA



Costs

 Outcomes Policy Questions

– Li it d Li

mit

e

d resources

– Which program to choose
CEA/CUA i CEA/CUA rev

iew

CEA h ff i d CEA compares t

he effect

iveness an

d

costs o two (or more) interventions

(Cos

tstudy

Cos

tusualcare

)

 

study 

y

Effectiveness

 Effectiveness

(

)

 Societal perspective 

Health Economics Resource Center
CEA/CUA review CEA/CUA review

 CEA compares the effectiveness an

costs of two (or more) interventions

– The effectiveness is defined by the he

is defined by the he

benefit or outcome achieved with the 

intervention.

Health Economics Resource Center
CEA/CUA review

 CEA and CUA require all outcome

CEA and CUA require all outcome

quantified in a single scale;

– A d i h it l i f ti i

A

d

a

y

in 

hospit

a

l or an 

i

n

fection avoi

– A day “free of angina pain”

– A day of “improved quality of life”.

Health Economics Resource Center
P ll1 o

 Wh b d i CEA What outcomes can be used in CEA

– Costs or Cost-savings– Hospital days– VR-36– QALYs– Infecti id d ons avoided

Health Economics Resource Center
CEA/CUA i CEA/CUA rev

iew

 Eff i b d i 

Effect

iveness can 

be measure

d

in n

units,

– Cost per avoided infection or hospita– Cost per day Cost per day

“free of free of anginal anginal pain

”

– Cost per gain in Life Year (LY).
CEA/CUA i CEA/CUA rev

iew

 Eff ti ec veness as a summary measur

– Quality of life, – Quantit

y of life, 

– Weighted by the societal preference f

qualit

y of life*
The Quality Adjusted Life Y

(QALY) 

 QALYs describe years of survival, 

adjusted for quality of life or preferadjusted for quality of life or prefer

Health Economics Resource Center
QALYs

 Y h 1 i f h lh 

You have 1 year in perfect health = 

QALY

 I have 1 year in “good” health (.80 

QALY)

 Difference = .20 QALYs 
QALY E l QALY

Examp

l

e

New cancer treatment vs. standard of careWeights range from 0-1

6 mo. 6 mo. 6 mo. 6 mo. Tot

New Txt.

.90

(.90 x .50)

.30

(.30 x .50)

.50

(.70 x .50)

.25 

(.25 x .50)

(.45+

=.537

.2

UC .90

(.90 x .50)

.50

(.50 x .50)

.25

(.25 x .50)

- (.45+

=.412

2

. 
Calculating cost/QALY

 ICER – New txt vs. standard care

(hypothetical all other costs are equal) (hypothetical all other costs are equal)

($10,000  $0/(.268 .2065)  $162,602
Estimating QALYs Estimating QALYs

 Requires:

– Description of the health states exper

by patients 

– Estimation of the duration of each he

state

– Comparison to or assessment of indiv

or community or community preferences preferences for each h

for each h

state

Health Economics Resource Center
Ind v du o co u y ividual or community

preferences

 CEA d i l i CEA and societal perspective

– Considers costs incurred by all partie– Allows comparisons across programs 

conditions

 For resource allocation/policy purposes
Deriving preferences or utilitie

Deriving preferences or utilitie

health states

 B i hdl Bas

ic met

h

o

d

o

logy:

– Individuals provide a personal reflect

the relative value (preference weight) different health states experienced or described.

 Patients Providers Communit

y p Sam

ple

Health Economics Resource Center
Deriving preferences or util

 Two methods to derive preferences: Two methods to derive preferences:

– Direct:– Indirect:

Health Economics Resource Center
M th d t f M

eth

o

ds 

to assess pre

feren

 Di h d rect met

h

o

d

– Individuals asked to choose (declare 

preferences) between their current he

state and alternative health status scen

– Individuals make these choices based 

their own com

p 

rehensive health state 

composite described to them).

Health Economics Resource Center
Samp p (p 

le health state description (comp

 You are able to see, hear and speak norm Y i h h l f h 

You require the help of another person t

or get around; and require mechanical 

equipment as well equipment as well.

 You are occasionally angry, irritable, an

and depressed and depressed.

 You are able to learn and remember nor Y bl b h d d 

You are able to eat, bathe, dress and use 

toilet normally.

 Y f f i d di f You are free of pain and discomfort.

Health Economics Resource Center
Direct: Standard Gamble 

( 

 Live rest of life in Live rest of life in

current health state; or

 “ k ill ( i h “ta

ke a pill

(

w

i

t

h

risks) to be restored to perfect health to perfect health

”

 Scale represents risk of death respondent is willing to bear in is willing to bear in order to be restored 

to full health.

Health Economics Resource Center
Direct: Time Tradeoff (TT

•How much How much

reduction in total life willin

g

to give up in order to live in perfect health

Health Economics Resource Center
M th d t f M

eth

o

ds 

to assess pre

feren

 I di h d I

ndirect met

h

o

d

– Individuals asked to rate preferences 

separat d i f h lth t t te 

doma

ins o

f

health s

t

a

tes

 Physical function Social functioning Social functioning Mental health etc.

– Scores are aggregated to create prefer

Scores are aggregated to create prefer

or utility weight for the composite he

state

Health Economics Resource Center
P ll 2 (f th EQ P

oll

2 (from the EQ

-5D)

 Whi h b d ib Whi

c

h statements 

best 

describes yo

today

 Mobility: (answer choices)No problem

problems, extreme problems

 Pain (same answer choices) Anxiety/depression Self-care Usual activit

y

Health Economics Resource Center
Ind ec p e e e ce e su e 

irect preference measure

systems

 H l h ili i Health utility measures vary in: 

– Dimensions or attributes included; – The size and nationality of the sample 

pp g 

o ulation used to establish the weigh

– Health states defined by the survey; a– How the summary score is calculated
Whi h th d t ? Whi

c

h meth

o

d

to use

?

 Trade-off between sensitivity and 

b d ur

den

 Start with a literature search re th

condition of interest

Health Economics Resource Center
Hi h f th d Hierarc

hy o

f meth

o

ds 

 Gi f l b d G

o

ing 

from 

least 

bur

densome to mo

–Off-the-shelf utilit

y values

– Indirect Measures 

(HUI EQ (HUI, EQ

-5D QWB SF 5D, QWB, SF

-6D)

–Use disease-s

p y

ecific surve

y durin

and transform later to preferences

–Direct meas re (SG TTO) Direct meas

ure (SG, TTO)

Health Economics Resource Center
Off-the-sh lf l e va ues

 U f i h d i di Use preference weight determined i

another study for health state of inte

– Not all health states have been charac

 Useful in decision modeling Useful in decision modeling

Health Economics Resource Center
Ind ec e su es irect measures

(HUI, EQ-5D, QWB, SF-6

 Standard surveys that are widely us R i bli h d t di Review published studies on 

psychometric properties in the popu

of interest

 May lack May lack “responsiveness responsiveness ”

Health Economics Resource Center
Using disease Using disease-specific surv

specific surv

 Use disease specific quality of life 

instrument if consequences of the treatment or disease are not capturea generic measure

 Have community p res ondents value 

health states with a direct measure alater time

Health Economics Resource Center
Using disease Using disease-specific surv

specific surv

 Key methods issues: 

– Difficult to describe health state to 

community p res ondent

– Difficult to establish values when the

larg p e number of possible health states 

 Expensive, but potentially sensitive 

variations in quality of life for this variations in quality of life for this

disease 

 Often used in addition to generic m

Often used in addition to generic m

Health Economics Resource Center
Direct Methods 

(, 

SG

, TTO

 May be necessary if effects of 

intervention are com

plex:

– Multiple domains– Effects not captured in indirect or dis

Effects not captured in indirect or dis

specific instruments

Health Economics Resource Center
Direct Method (SG TTO

Direct Method (SG, TTO

 Hi h i i i f 

Hi

g

h var

iance 

in est

imates 

from pat

in a trial

– Reflect risk aversion, feeling about 

disabilit

y

– High variance = large sample size

 Not the “comm nit al e” specifie

Not the “comm

unity val

ue” specifie

Gold et al 

Health Economics Resource Center
Methods to assess preferences 

h lth t t health s

t

a

tes

 Indirect Measures

– Health Utility Index (HUI)– EuroQol (EQ

-5D)

– Quality of Well-Being Scale (QWB)– SF-6D 

Health Economics Resource Center
Indirect measures: Health Ut

I d (HUI) I

n

dex (HUI)

 41 

q ( y pp 

uestions 

(man

y items can be skipped

– can derive both HUI Mark 2 and HUI Mark 

health utility scores.

 8 domains of health and 972,000 health 

– vision, hearing, speech, ambulation, dexter

emoti iti d i tion, cognition, an

d pa

i

n

 Basis of domain weights:

– Canadian community sample rated hypothe

Canadian community sample rated hypothe

health states

– Utilit

y y theor

y

Health Economics Resource Center
Ind ec e su es: irect measures:

EuroQol EQ-5D

 5 i i 5d i fh lh 5 questions in 5 domains of health

– Mobility, self-care, usual activity, pain/dis

or anxiety/depression

– 245 health states.

 Basis of domain weights:

– Past studies based on British community 

 sa

– New US weights recently published

Health Economics Resource Center
Indirect measures: the QW

Quality of Well-Being Scal

 Two versions

– Interviewer or self-administered (QW

 QWB

-SA is more feasible, but still 

SA is more feasible, but still 

time

– 76 questions; 1215 health states defin

76 questions; 1215 health states defin

– Includes symptoms, mobility, physica

activity & social activity activity, 

& social activity

 Basis of domain weights:

– P i ti t i S Di C

P

r

imar

y care patien

ts 

in 

San Di

e

go, C

Health Economics Resource Center
Indirect measures: SF-6

 Converts SF-36 or SF-12 scores to 

utilities

– When based on SF-36, uses 10 items– When based on SF When based on SF

-12, uses 7 items 12, uses

7 items

 6 health domains

– physical functioning role limitations socia

physical functioning, role limitations, socia

functioning, pain, mental health, and vitali

 Defines 18 000 health states Defines 18

,000 health states

 Basis of domain weights

– Biih i l B

r

i

t

i

s

h commun

ity samp

l

e

Health Economics Resource Center
Important Resources 

 Harvard Center for Risk Assessmen

– http://www hcra harvard edu/ http://www.hcra.harvard.edu/

 Brazier J, Deverill M, Green C, Ha

R Booth A A Review of the use of R, Booth A. A Review of the use of

health status measures in economic 

evaluation Health evaluation. Health Technol Technol Assess

1999;3(9).

– h // h k/932 http://www.hta.ac.uk/932

Health Economics Resource Center
I t tR mportant Resources

 T bl f bli h d tilit i ht Table of published utility weights 

(preferences) for different health sta

– http://www.tufts-nemc.org/cearegistr
HERC

 PL Si J JR B PG PL Sinnott, Joyce, JR, Barnett, PG. 

Preference Measurement in Econom

Analysis. Guidebook. Menlo Park, 

VA Palo Alto Health Economics 

Resource Center. 2007 (see HERC website)

Health Economics Resource Center
QUESTIONS and COMMENT

Health Economics Resource Center