Quality of Life:

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Quality of Life What Are We Measuring?
Geraldine Padilla, PhD Professor and Associate
Dean UCSF School of Nursing
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WHAT ARE WE MEASURING?

• What do you want to measure?
• Why do you want to measure QOL?
• How will QOL be measured?
• What is the meaning of a QOL score?

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WHAT DO YOU WANT TO MEASURE?

• Global measure
• Health-related measure
• Unidimensional measure
• Multidimensional measure

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WHAT DO YOU WANT TO MEASURE?

• QOL Global definition focus on perceived gap
• the extent to which hopes and
• ambitions are matched by
• experience (Calman, 1984)

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WHAT DO YOU WANT TO MEASURE?

• QOL Global definition focus on personal judgment
  of positive negative attributes
• a personal statement of the positivity or
  negativity of attributes that characterize ones
  life (Grant, Padilla, Ferrell, Rhiner, 1990 )

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WHAT DO YOU WANT TO MEASURE?

• QOL Global definition focus on perceived
  position compared to personal criteria, i.e. gap
• " an individual's perception of their
• position in life in the context of the
• culture and value systems in which
• they live and in relation to their goals,
  expectations, standards concerns. (WHO, 1993)

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WHAT DO YOU WANT TO MEASURE?

• QOL Global definition focus on perceived
  satisfaction and importance
• an individuals perceptions of well-
• being that stem from satisfaction or
• dissatisfaction with dimensions of life that are
  important to the individual (Ferrans, Powers,
  1985)

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WHAT DO YOU WANT TO MEASURE?

• QOL health-related definition focus is
  uni-dimensional on physical function
• (Karnofsky, 1949)

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WHAT DO YOU WANT TO MEASURE?

• QOL health-related definition focus on
  self-report of two-dimensional factors
• QOL refers to a person or group's perceived
  physical and mental health over time.
  (http//www.cdc.gov/hrqol/)

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WHAT DO YOU WANT TO MEASURE?

• QOL health-related definition focus on realistic
  self-report of multi-dimensional aspects
• a pragmatic, day to day, functional
• representation of a patients physical,
  psychological, and social response to a disease
  and its treatment (Schipper, 1990)

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WHAT DO YOU WANT TO MEASURE?

• QOL health-related definition Focus on
  satisfaction with function based on perceived gap
• Patients appraisal of and satisfaction with
  their current level of functioning as compared to
  what they perceive to be possible or ideal
  (Cella, Tulsky, 1990)

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WHAT DO YOU WANT TO MEASURE?

• QOL health-related definition focus on level
  satisfaction with function
• control over illness
• state of well-being...composite of ability to
  perform everyday activities which reflect
  physical, psychological and social well-being,
  and patient satisfaction with levels of
  functioning and the control of disease and/or
  treatment related symptoms (Gotay et al., 1992)

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WHAT DO YOU WANT TO MEASURE?

• QOL health-related definition focus on
  multidimensional factors in context of survival
  time
• "Health-related QOL is the value assigned to
  duration of life as modified by the impairments,
  functional states, perceptions and social
  opportunities influenced by disease, injury,
  treatment or policy. (Patrick, Erickson, 1993)

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WHAT DO YOU WANT TO MEASURE?

• QOL health-related definition focus on
  self-report of multi-dimensional factors
• "... a unique perception, denoting
• the way that individual patients feel
• about their health status and/or
• nonmedical aspects of their lives. (Gill and
  Feinstein, 1994)

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WHAT DO YOU WANT TO MEASURE? Summary of HRQOL
definitions

• Function, well-being (phy, psych, soc, spirit)
• Personal judgment weighing good and bad aspects
  of life in context of culture, values
• Value placed on duration of life modified by
  disease, treatment, policy
• Ability to perform everyday activities
• Satisfaction with important dimensions of
  well-being, e.g. function
• Gap between hope experience, ideal possible,
  expectations current position
• Control over disease

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WHY DO YOU WANT TO MEASURE QUALITY OF LIFE?

• Is QOL a measure of treatment efficacy?
• Is QOL a measure of the quality of survivorship?
• What are the QOL consequences of research
  interventions, treatment, care?
• Do patients and clinicians see the patients QOL
  in the same way?

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WHY DO YOU WANT TO MEASURE QUALITY OF LIFE?

• Do patients consider length of life or QOL more
  important?
• Is prolonging life at any QOL cost reasonable,
  desirable?
• Is cure the most important outcome?
• Is relief of physical symptoms enough?
• Do symptom clusters determine QOL level?

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WHY DO YOU WANT TO MEASURE QUALITY OF LIFE?

• Do potential QOL outcomes influence health
  policy?
• Because resources are finite, do QOL
  considerations influence who gets treated?
• Do potential QOL outcomes influence physicians
  treatment recommendations, and patients
  treatment choice?

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HOW WILL QUALITY OF LIFE BE MEASURED?

• Quality of Life theory
• Measurement theory
• Reliability, validity
• Domains, dimensions, subscales
• Qualitative and/or quantitative methods
• Questionnaires, standardized instruments,
  websites

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HOW DO YOU WANT TO MEASURE QOL?QOL THEORY

• Importance of QOL Theory
• Impose conceptual clarity by distinguishing
  between predictors and attributes of HRQL
• QOL Predictor symptom severity, intensity,
  frequency
• QOL Attribute perceived symptom distress

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HOW DO YOU WANT TO MEASURE QOL?QOL THEORY
PREDICTORS, DOMAINS

Physical well-being Symptoms
Psychological well-being
Pain
Spiritual well-being
Social well-being
Ferrell, Grant, Padilla et al., 1991
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HOW DO YOU WANT TO MEASURE QOL?QOL THEORY
PREDICTORS, DOMAINS
Duration of Life Disease and Injury Impairments
Environment
Prognosis Physical-Psych-Social Func.
Health Perceptions Opportunity for Health

Patrick, Erickson, 1993
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HOW DO YOU WANT TO MEASURE QOL?QOL THEORY
PREDICTORS, DOMAINS


Wilson, Cleary 1995

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HOW DO YOU WANT TO MEASURE QOL?QOL THEORY
PREDICTORS, DOMAINS

• Response Shift HRQOL (Sprangers
  Schwartz, 1999)
• 
  
  

Antecedents
Accommodation Process Appraisal Accommod.
Discrepancy Mechanisms Cope
Compare
Reorder goals Reframe
expectations

QOL Outcomes Response Shift
QOL Reconceptualize Recalibrate Reprioritize

Catalysts
Sprangers, Schwartz, 1999
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HOW DO YOU WANT TO MEASURE QOL?QOL THEORY
PREDICTORS, DOMAINS
Ashing-Giwa, 2005
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HOW DO YOU WANT TO MEASURE QOL?MEASUREMENT
THEORY/MODELS

• Classical Test Theory
• Traditional psychometrics, validity (e.g. factor
  
• analysis) and reliability (e.g. Cronbachs
  alpha),
• are critical characteristics of tests/scales.
• Measurement scales based on averages or
• simple summations of scale items.

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HOW DO YOU WANT TO MEASURE QOL?MEASUREMENT
THEORY/MODELS

• Item Response Theory
• mathematical models that describe, in
  probabilistic terms, relationships between
  response to a survey question and ones level of
  the latent variable measured (p. 55)
• Latent variable Construct that cant be directly
  measured by a single observable variable or item.
  Indirectly measured with multiple items in a
  multi-item scale. (p. 56)

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HOW DO YOU WANT TO MEASURE QOL?MEASUREMENT
THEORY/MODELS

• Item Response Theory
• Level of QOL accounts for ones probable
  response to each item in a QOL questionnaire.
• Value of IRT Investigator can determine
• contribution of each item in measuring the
  underlying construct
• redundancy of an item relative to other items in
  the scale
• appropriateness of response categories (Reeve,
  Fayer p. 63)

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HOW DO YOU WANT TO MEASURE QOL?OTHER MEASUREMENT
ISSUES

• Reliability
• Validity
• Domain/dimension subscales

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HOW DO YOU WANT TO MEASURE QOL?METHODOLOGICAL
CONSIDERATIONS

• Different results with different methods
• Qualitative methods - thematic analysis of data
  from interviews
• Quantitative instruments - standardized or home
  grown questionnaires
• Global, health-related
• domain specific

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HOW DO YOU WANT TO MEASURE QOL?METHODOLOGICAL
CONSIDERATIONS

• Translated or linguistically-culturally tailored
  measures equivalence across cultures or
  languages
• Conceptual (equivalent domains, determined
  qualitatively)
• Items (measure same domain, are relevant)
• Semantic (words, phrases have same meaning)
• Operational (same format, scoring, item scaling)
• Measurement (reliability, validity, means, SDs)
• Function (instrument does what it is supposed to
  do equally well across cultures/languages
• (Herdman, Fox-Rushby, Badia, 1998)

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HOW DO YOU WANT TO MEASURE QOL?METHODOLOGICAL
CONSIDERATIONS

• Different results with different methods
• Self-report and/or proxy report
• Short and/or long time period
• Single or multiple measures
• Short or long measures
• Home, clinic, hospital, community
• Time of measurement in relation to a catalyst

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HOW DO YOU WANT TO MEASURE QOL?RESPONDENT
CONSIDERATIONS

• Different measures for different populations
• Adult, adolescent, child
• Healthy, ill, survivor
• Type of illness, disease, symptom
• Health care provider, caregiver
• Men, women

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HOW DO YOU WANT TO MEASURE QUALITY OF LIFE?

• Websites of Quality of Life Measures
• BiblioPro QOL questionnaires in Spanish
• http//bibliopro.imim.es/
• Center for QOL Research in Nursing Science
• http//www.uib.no/isf/people/doc/qol/httoc.htm
• Brown University
• http//www.chcr.brown.edu/pcoc/Quality.htm
• Center for Disease Control and Prevention
• http//www.healthmeasurement.org/Measures.html
• Websites for disease/symptom-related QOL Meas.

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MEANING OF QOL SCORES

• Missing data
• Implicit theories of change response shift
• Confounding variables
• Linear and nonlinear relationships
• Clinical versus statistical significance

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Physical Well-being U-shaped quadratic model

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Physical Well-being patterns of 82 Subjects

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Physical Well-being U-shaped pattern

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Physical Well-being Flat-high pattern

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Clinical versus Statistical Significance
• Q. What is the minimal clinically important
  difference (MCID)?
• A. It is the smallest difference which patients
  perceive as beneficial and would mandate, in the
  absence of troublesome side effects and excessive
  cost, a change in the patients management.
  (Jaeschke, et al., 1989)

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Clinical versus Statistical Significance
• For the SF-36 MCID typically in 3-5 point
  range difference of 1 - 2 points not important
  (Samsa 1999, p. 149)
• Value of achieving a MCID depends on the cost to
  produce the change
• MCID can be misleading when using average change
  scores (e.g. 10 Ss 3 change, 10 Ss 0 change. M
  1.05)

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Clinical versus Statistical Significance
• What change in care management is warranted
  based on a patients report of minimum
  discernable difference or clinicians judgment of
  clinically significant difference?
• MCID for HRQoL may differ with context such as
  adjuvant therapy versus palliative treatment.

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MEANING OF QOL SCORES?ANALYSIS INTERPRETATION

• Clinical versus Statistical Significance
• MCID estimation problems
• Magnitude of change varies depending on
  distribution and external standard
• Amount of change may depend on the direction of
  change
• Meaning of change depends on where you start
  (baseline value)

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WHAT ARE WE MEASURING?

• What do you want to measure?
• Why do you want to measure QOL?
• How will QOL be measured?
• What is the meaning of a QOL score?

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Thank You! Questions?
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