Quality of LifeQuality of Life

Stephen McKennaGalen Research, Manchester,

UK

AimAim

To introduce the concept of Quality of Life and distinguish it from HRQL

Types of patient-reported Types of patient-reported outcomesoutcomes

Quality of life

Impairment (well-being)

Disability (functioning)

Handicap (participation)

Health-related quality of life

(HRQL)/(Health status)

=

Impairment Impairment

Loss or abnormality of psychological, physiological or anatomical structure or function

Equates to symptoms

Disturbances at level of organ

Fatigue, pain, dizziness, depression, sleep problems

Main value of assessing Main value of assessing impairmentimpairment

Determining the impact of the disease from a clinical viewpoint

Determining appropriate intervention(s)

Note: impairment includes disease severity and adverse treatment effects, such as pain, acne or bruising

Disability (activity)Disability (activity) Any restriction or lack of ability to perform

an activity in the manner or within the range considered normal for a human being

Equates to functioning or functional status

Examples include restricted mobility, problems dressing & bathing, social restrictions, problems showing affection

HRQL measures (such as SF-36) commonly assess functioning in addition to impairment

Value of assessing disability Value of assessing disability (activity) (activity)

Planning rehabilitation services

Looking at impact of disease on society

However,

Focus on functioning gives potential for cultural bias

Examples of impairments, Examples of impairments, disabilities and handicapsdisabilities and handicaps

Impairments

Pain

Fatigue

Anxiety

Incontinence

Disabilities

Bathing

Dressing

Climbing Stairs

Ability to work

Socrates (469-399 BC)

Quoted by Plato

““We should set the highest We should set the highest value, not on living, but on value, not on living, but on living well”living well”

No account taken of preferences, other influences or emotional response

Provide a framework for assessing interventions from clinical rather than patient perspective

I and D represent the consequences of disease in terms of deviation from norms

Development of the Development of the Needs-based ModelNeeds-based Model

Hunt & McKenna, 1992

Study on QoL in depressed patients

Only valid method of developing the instrument was to derive the content from interviews with relevant patients

Impact of disease related to inability to meet needs rather than functional limitations

Individuals are driven or motivated by their needs

Fulfilment of these needs provides for satisfaction

Money, employment etc are important only insofar as they allow needs to be fulfilled

Patient interviews revealed …Patient interviews revealed …

Identity

Status

Time Structure

Shared Goals

Socialisation

Identity

Status

Time Structure

Shared Goals

Socialisation

Income

ObjectivObjectivee

Employment-related needsEmployment-related needs

FunctioFunctionn

Needs Needs fulfilledfulfilled

The Needs-based QoL modelThe Needs-based QoL model

Life derives its quality from the ability and capacity of the individual to satisfy

certain human needs

Quality of life is: Highest when most needs are fulfilled Lowest when few needs are satisfied

QoL is an unidimensional construct - providing an index rather than a profile

“Human life quality is dependent upon the

satisfaction of certain basic needs - lack of

disease, mobility, adequate nutrition

and shelter.”

Sir Thomas More (1478-1535) Sir Thomas More (1478-1535)

Health-Related Quality of LifeHealth-Related Quality of Life Assesses I and D as multi-dimensional

construct

SF-36, NHP, SIP, EQ-5D, PGWB

Assumes:• health most important influence• health does not interact with other

influences

Researchers now differentiate HRQL from QoL

Gill & Feinstein; 1994Gill & Feinstein; 1994

Rather than being HRQL or health status..

“QoL is a reflection of the way in which

patients perceive and react to their

health status and to other non-medical

aspects of their lives.”

HRQL ≠ QoLHRQL ≠ QoL

“I try to lead as normal a life as

possible,and not think about

my condition, orregret the things it prevents me from

doing,which are not that

many.” Stephen Hawking

PersonalityPersonality

QoLQoL

DiseaseDisease

Culture /economy

Culture /economy

SocialSocial

HRQLHRQL

TreatmentTreatment

Impairments

(symptoms)

Impairments

(symptoms)

Disability(functioning)

Disability(functioning)

DemographicsDemographics

EnvironmentEnvironment

Influences on quality of lifeInfluences on quality of life

Spot the differenceSpot the difference

Can we differentiate HRQL from QoL items?

The following 11 items assess HRQL or QoL.

Can you tell which construct is measured by each item?

The SolutionThe Solution

QoLI can't put energy into my close relationships

5

QoLI've lost interest in food4

HRQLAre you able to have an all over wash?

3

QoLI feel guilty asking for help 2

HRQLI get breathless walking up a slight slope

1

The Solution (2)The Solution (2)

QoLI feel vulnerable when I'm on my own

10

QoLI have to talk very quietly 9

QoLI can't do things on the spur of the moment

8

HRQLAre you able to walk around inside the house?

7

HRQLI feel hopeless 6

I get dizzy spells most days 11 HRQL

Provide a patient-based endpoint

No pre-determined “components”Separate from but complementary

to HRQL endpoints

Based on a coherent model

QoL endpoint does not aid diagnosis nor guide treatment

Needs-based measuresNeeds-based measures

Avoids asking about functions- fewer missing data

Copes better with adaptation Facilitates cross-cultural

development / adaptation Facilitates development of

disease-specific instruments Provides an index of QoL

Response rates (%)

Growth hormone deficiency 98

Migraine 97

Genital herpes 92

Depression 91

UK versions

Response rates forResponse rates fortest-retest postal test-retest postal

administrationadministration

UK versions

Test-retest correlation

Alpha coefficient

No. of items

Depression 0.94 0.95 34

Genital herpes 0.92 0.95 20

Migraine 0.94 0.94 20

GHD 0.90 0.95 25

Incontinence 0.92 0.89 17

Reproducibility of needs-based Reproducibility of needs-based QoL instrumentsQoL instruments

Reproducibility of QoL-AGHDAReproducibility of QoL-AGHDA

Country Alpha Test-retest

UK 0.93 0.93US 0.88 0.88Belgium (French) 0.95 0.88Belgium (Flemish) 0.91 0.91Denmark 0.93 0.89Italy 0.89 0.85Germany 0.90 0.89Netherlands 0.88 0.94Spain 0.88 0.91Sweden 0.92 0.93

Severity of depression*

Mean QLDS n

HDRS <4 None 1.5 15

HDRS 4 - 7 Mild 6.5 14

HDRS 8 -

20Moderate 12.6 163

HDRS >20 Severe 21.8 79

* Hamilton Depression Rating Scale

Known groups validity for the QLDSKnown groups validity for the QLDS

Responsiveness of the QLDS:Responsiveness of the QLDS:General practice populationGeneral practice population

0

5

10

15

20

25

0 4 8 12 16 20 24

Weeks since baseline

Median QLDS score

Effect size >2

Effect sizes for QLDS and SF-36Effect sizes for QLDS and SF-36

0.0

0.5

1.0

1.5

2.0

2.5Q

LD

S

QL

DS

(E

)

ER

SF

MH

VIT PR

GH

PA

IN PF

SF-36 sections

Change in QoL Change in QoL of parents of of parents of children with children with atopic atopic dermatitisdermatitis Moderate

Almost clear

Mild

Needs-based QoL measuresNeeds-based QoL measuresDepression QLDSMigraine MSQOLAlzheimer's carers’ ACQLIUrogenital atrophy UGAQoLIncontinence IQoLIErectile dysfunction MEDQOLRecurrent genital herpes RGHQoLRheumatoid arthritis RAQoLAnkylosing spondylitis ASQoLSystemic lupus erythematosus SLEQoLPsoriatic arthritis PSAQoLAdult atopic dermatitis QoLIADChildhood atopic dermatitis PIQoL-ADPsoriasis PSORIQoLAdult growth hormone deficiency QoL-AGHDA

Treatment compliance and Treatment compliance and QoLQoL

0

2

4

6

8

10

12

14

16

Refusedtreatment

Acceptedtreatment

Mea

n Q

oL-A

GH

DA

0

2

4

6

8

10

12

14

16

Refusedtreatment

Acceptedtreatment

Mea

n Q

oL-A

GH

DA

Treatment with recombinant human growth hormone where individual: has severe GH deficiency, is already receiving treatment, and has impaired QoL as demonstrated by a score of at least 11 on the QoL-AGHDA

GH treatment should be discontinued if after 9 months the individual has an improvement of fewer than 7 points on the QoL-AGHDA

Generating disease-specific Generating disease-specific utilityutility

Preference for health states Reasonable to base these on QoL impact Subset of QoL items as characteristics Value states using standard methods:

• Standard gamble, TTO, ranking or CA Incorporate into relative or absolute

utility and QALY-type analyses

RGHQoL scenarioRGHQoL scenario

Herpes makes it quite difficult for me to plan ahead

It is very difficult to forget that I have herpes

Herpes is affecting my sex life a little

I get very depressed about having herpes

I worry quite a lot about people I know finding out I have herpes

I become a little tense when someone touches me

Comparison of ranking of 25 herpes Comparison of ranking of 25 herpes health states using CA and TTO health states using CA and TTO

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

CA TTO

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Cross disease comparisonsCross disease comparisons

Generic questionnaires only available option for making comparisons across diseases

However:possess inferior psychometric propertiespoor sensitivity to change in health statuswork in different way in each disease group

Cross disease utilityCross disease utility

The same issues apply to generic utility measures such as the EQ-5D, SF-6 and HUI

Respondents interpret items differently so that responses have different values for different diseases

The implication is that such generic measures do not provide a valid comparison of utility gains across diseases

Co-calibration of disease Co-calibration of disease specific QoL instrumentsspecific QoL instruments

RAQoL (rheumatoid arthritis) and QoL-AGDHA (adult growth hormone deficiency) selected, as:

based on same model of QoLexcellent psychometric propertiesemploy same response systemhave QoL issues in common

Common item equating most economic method of item equating• Subtest of items contained in each

scale Ten linking items identified

• free from DIF by diagnosis, age, gender, time

• Logit range -1.14 to 1.47

Percentage of "Yes" Percentage of "Yes" responses for common items responses for common items

by diagnosis group by diagnosis group

1

6

8

11

13 16

18

1

6

8

11 13

16

18 17

12

10

17

12

10

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

1 6 8 10 11 12 13 16 17 18 Question Number

Pe

rce

nta

ge

Re

sp

on

se

RA % GHD %

Item bankingItem banking Items fit same measurement model Value for different diseases Select relevant common items for co-

calibration Rheumatology item bank

Rheumatoid arthritis (RAQoL)Ankylosing spondylitis (ASQoL)Psoriatic arthritis (PSAQoL)Lupus (SLEQoL)Osteoarthritis (OAQoL)

The future of QoL assessment?The future of QoL assessment?

Highly acceptable and relevant scales

Excellent accuracy and responsiveness

Valid cross-disease comparisons by co-calibration of scales employing the needs model

Production of disease-specific utilities