Quality of Life: What Are We Measuring? Geraldine Padilla, PhD Professor and Associate Dean

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

2. 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?

3. WHAT DO YOU WANT TO MEASURE? • Global measure • Health-related measure • Unidimensional measure • Multidimensional measure

4. 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)

5. 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 )

6. 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)

7. 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)

8. WHAT DO YOU WANT TO MEASURE? QOL health-related definition: focus is uni-dimensional on physical function (Karnofsky, 1949)

9. 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/)

10. 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)

11. 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)

12. 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)

13. 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)

14. 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)

15. 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

16. 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?

17. 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?

18. 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?

19. 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

20. 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

21. 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

22. 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

23. HOW DO YOU WANT TO MEASURE QOL?QOL THEORY: PREDICTORS, DOMAINS Wilson, Cleary 1995

24. 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

25. HOW DO YOU WANT TO MEASURE QOL?QOL THEORY: PREDICTORS, DOMAINS Ashing-Giwa, 2005

26. 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.

27. 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)

28. 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)

29. HOW DO YOU WANT TO MEASURE QOL?OTHER MEASUREMENT ISSUES • Reliability • Validity • Domain/dimension subscales

30. 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

31. 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)

32. 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

33. 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

34. 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.

35. MEANING OF QOL SCORES • Missing data • Implicit theories of change & response shift • Confounding variables • Linear and nonlinear relationships • Clinical versus statistical significance

36. MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION Physical Well-being – U-shaped quadratic model

37. MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION Physical Well-being – patterns of 82 Subjects

38. MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION Physical Well-being – U-shaped pattern

39. MEANING OF QOL SCORES?ANALYSIS & INTERPRETATION Physical Well-being – Flat-high pattern

40. 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)

41. 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)

42. 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.

43. 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)

44. 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?

45. Thank You! Questions?