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Quality of Life: What Are We Measuring? Geraldine Padilla, PhD Professor and Associate Dean UCSF School of Nursing. 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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slide1

Quality of Life:

What Are We Measuring?

Geraldine Padilla, PhD

Professor and Associate Dean

UCSF School of Nursing

what are we measuring
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?
what do you want to measure
WHAT DO YOU WANT TO MEASURE?
  • Global measure
  • Health-related measure
  • Unidimensional measure
  • Multidimensional measure
what do you want to measure1
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)

what do you want to measure2
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 one’s life” (Grant, Padilla, Ferrell, Rhiner, 1990 )

what do you want to measure3
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)

what do you want to measure4
WHAT DO YOU WANT TO MEASURE?

QOL Global definition: focus on perceived satisfaction and importance

“an individual’s perceptions of well-

being that stem from satisfaction or

dissatisfaction with dimensions of life that are important to the individual” (Ferrans, Powers, 1985)

what do you want to measure5
WHAT DO YOU WANT TO MEASURE?

QOL health-related definition: focus is uni-dimensional on physical function

(Karnofsky, 1949)

what do you want to measure6
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/)

what do you want to measure7
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 patient’s physical, psychological, and social response to a disease and its treatment” (Schipper, 1990)

what do you want to measure8
WHAT DO YOU WANT TO MEASURE?

QOL health-related definition: Focus on satisfaction with function based on perceived gap

“Patient’s appraisal of and satisfaction with their current level of functioning as compared to what they perceive to be possible or ideal” (Cella, Tulsky, 1990)

what do you want to measure9
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)

what do you want to measure10
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)

what do you want to measure11
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)

what do you want to measure summary of hrqol definitions
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
why do you want to measure quality of life
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 patient’s QOL in the same way?
why do you want to measure quality of life1
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?
why do you want to measure quality of life2
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?
how will quality of life be measured
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
how do you want to measure qol qol theory
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
how do you want to measure qol qol theory predictors domains
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

how do you want to measure qol qol theory predictors domains1
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

how do you want to measure qol qol theory predictors domains3
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

how do you want to measure qol measurement theory models
HOW DO YOU WANT TO MEASURE QOL?MEASUREMENT THEORY/MODELS

Classical Test Theory

  • Traditional psychometrics, validity (e.g. factor

analysis) and reliability (e.g. Cronbach’s alpha),

are critical characteristics of tests/scales.

  • Measurement scales based on averages or

simple summations of scale items.

how do you want to measure qol measurement theory models1
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 one’s level of the ‘latent variable’ measured (p. 55)
  • Latent variable: Construct that can’t be directly measured by a single observable variable or item. Indirectly measured with multiple items in a multi-item scale. (p. 56)
how do you want to measure qol measurement theory models2
HOW DO YOU WANT TO MEASURE QOL?MEASUREMENT THEORY/MODELS

Item Response Theory:

  • Level of QOL accounts for one’s 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)
how do you want to measure qol other measurement issues
HOW DO YOU WANT TO MEASURE QOL?OTHER MEASUREMENT ISSUES
  • Reliability
  • Validity
  • Domain/dimension subscales
how do you want to measure qol methodological considerations
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
how do you want to measure qol methodological considerations1
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)

how do you want to measure qol methodological considerations2
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
how do you want to measure qol respondent considerations
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
how do you want to measure quality of life
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.
meaning of qol scores
MEANING OF QOL SCORES
  • Missing data
  • Implicit theories of change & response shift
  • Confounding variables
  • Linear and nonlinear relationships
  • Clinical versus statistical significance
meaning of qol scores analysis interpretation
MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION

Physical Well-being – U-shaped quadratic model

meaning of qol scores analysis interpretation1
MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION

Physical Well-being – patterns of 82 Subjects

meaning of qol scores analysis interpretation2
MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION

Physical Well-being – U-shaped pattern

meaning of qol scores analysis interpretation3
MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION

Physical Well-being – Flat-high pattern

meaning of qol scores analysis interpretation4
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 patient’s management.” (Jaeschke, et al., 1989)

meaning of qol scores analysis interpretation5
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)
meaning of qol scores analysis interpretation6
MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION

Clinical versus Statistical Significance:

  • What change in care management is warranted based on a patient’s report of minimum discernable difference or clinician’s judgment of clinically significant difference?
  • MCID for HRQoL may differ with context such as adjuvant therapy versus palliative treatment.
meaning of qol scores analysis interpretation7
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)
what are we measuring1
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?
slide45

Thank You!

Questions?