Quality of Life

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Quality of Life

• Stephen McKenna
• Galen Research, Manchester, UK

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

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Types of patient-reported outcomes
Health-related quality of life (HRQL)/ (Health
status)
Impairment (well-being) Disability
(functioning) Handicap (participation)

Quality of life
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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

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Main value of assessing impairment

• 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

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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

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Value of assessing disability (activity)

• Planning rehabilitation services
• Looking at impact of disease on society

However, Focus on functioning gives potential for
cultural bias
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Examples of impairments, disabilities and
handicaps

• Impairments
• Pain
• Fatigue
• Anxiety
• Incontinence

Disabilities Bathing Dressing Climbing
Stairs Ability to work
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Socrates (469-399 BC) Quoted by Plato
We should set the highest value, not on living,
but on living well
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I and D represent the consequences of disease in
terms of deviation from norms

• No account taken of preferences, other influences
  or emotional response
• Provide a framework for assessing interventions
  from clinical rather than patient perspective

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Development of the Needs-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

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Patient interviews revealed

• 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

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Employment-related needs
Objective
Function
Needs fulfilled
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The 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

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Sir Thomas More (1478-1535)
Human life quality is dependent upon the
satisfaction of certain basic needs - lack of
disease, mobility, adequate nutrition and
shelter.
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Health-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

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Gill 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.
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HRQL ? QoL
I try to lead as normal a life as possible, and
not think about my condition, or regret the
things it prevents me from doing, which are not
that many. Stephen Hawking
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Influences on quality of life
Disease
Treatment
Impairments (symptoms)
Disability (functioning)
HRQL
Personality
Demographics
QoL
Culture / economy
Social
Environment
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Spot 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?

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The Solution
HRQL
I get breathless walking up a slight slope
1
I feel guilty asking for help
QoL
2
HRQL
Are you able to have an all over wash?
3
QoL
I've lost interest in food
4
QoL
I can't put energy into my close relationships
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The Solution (2)
HRQL
I feel hopeless
6
HRQL
Are you able to walk around inside the house?
7
QoL
I can't do things on the spur of the moment
8
QoL
I have to talk very quietly
9
QoL
I feel vulnerable when I'm on my own
10
I get dizzy spells most days
11
HRQL
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Needs-based measures

• 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

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• 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

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Response rates for test-retest postal
administration
UK versions
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Reproducibility of needs-based QoL instruments
UK versions
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Reproducibility of QoL-AGHDA

• Country Alpha
  Test-retest
• UK 0.93 0.93
• US 0.88 0.88
• Belgium (French) 0.95 0.88
• Belgium (Flemish) 0.91 0.91
• Denmark 0.93 0.89
• Italy 0.89 0.85
• Germany 0.90 0.89
• Netherlands 0.88 0.94
• Spain 0.88 0.91
• Sweden 0.92 0.93

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Known groups validity for the QLDS
Severity of depression Severity of depression Mean QLDS n
HDRS lt4 None 1.5 15
HDRS 4 - 7 Mild 6.5 14
HDRS 8 - 20 Moderate 12.6 163
HDRS gt20 Severe 21.8 79
Hamilton Depression Rating Scale
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Responsiveness of the QLDSGeneral practice
population
Effect size gt2
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Effect sizes for QLDS and SF-36
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Change in QoL of parents of children with atopic
dermatitis
Moderate
Mild
Almost clear
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Needs-based QoL measures
Depression QLDS
Migraine MSQOL
Alzheimer's carers ACQLI
Urogenital atrophy UGAQoL
Incontinence IQoLI
Erectile dysfunction MEDQOL
Recurrent genital herpes RGHQoL
Rheumatoid arthritis RAQoL
Ankylosing spondylitis ASQoL
Systemic lupus erythematosus SLEQoL
Psoriatic arthritis PSAQoL
Adult atopic dermatitis QoLIAD
Childhood atopic dermatitis PIQoL-AD
Psoriasis PSORIQoL
Adult growth hormone deficiency QoL-AGHDA
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Treatment compliance and QoL
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• 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

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Generating disease-specific utility

• 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

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RGHQoL 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

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Comparison of ranking of 25 herpes health states
using CA and TTO
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Cross disease comparisons

• Generic questionnaires only available option for
  making comparisons across diseases
• However
• possess inferior psychometric properties
• poor sensitivity to change in health status
• work in different way in each disease group

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Cross 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

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Co-calibration of disease specific QoL instruments

• RAQoL (rheumatoid arthritis) and QoL-AGDHA
  (adult growth hormone deficiency) selected, as
• based on same model of QoL
• excellent psychometric properties
• employ same response system
• have QoL issues in common

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• 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

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Percentage of "Yes" responses for common items by
diagnosis group
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Item 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)

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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