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Quality of Life

Quality of Life. Stephen McKenna Galen Research, Manchester, UK. Aim To introduce the concept of Quality of Life and distinguish it from HRQL. Types of patient-reported outcomes. Health-related quality of life (HRQL)/ (Health status). Impairment (well-being) Disability (functioning)

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Quality of Life

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  1. Quality of Life Stephen McKenna Galen Research, Manchester, UK

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

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

  4. 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

  5. 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

  6. 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

  7. Value of assessing disability (activity) • Planning rehabilitation services • Looking at impact of disease on society However, Focus on functioning gives potential for cultural bias

  8. Impairments Pain Fatigue Anxiety Incontinence Examples of impairments, disabilities and handicaps Disabilities Bathing Dressing Climbing Stairs Ability to work

  9. Socrates (469-399 BC) Quoted by Plato “We should set the highest value, not on living, but on living well”

  10. 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

  11. 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

  12. 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

  13. Employment Employment-related needs Objective Function Needs fulfilled

  14. 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 The Needs-based QoL model

  15. 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.”

  16. 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

  17. 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.”

  18. 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

  19. Influences on quality of life Disease Treatment Impairments (symptoms) Disability (functioning) HRQL Demographics Personality QoL Culture / economy Social Environment

  20. 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? Spot the difference

  21. The Solution 1 I get breathless walking up a slight slope HRQL I feel guilty asking for help 2 QoL 3 Are you able to have an all over wash? HRQL 4 I've lost interest in food QoL 5 I can't put energy into my close relationships QoL

  22. The Solution (2) 6 I feel hopeless HRQL 7 Are you able to walk around inside the house? HRQL 8 I can't do things on the spur of the moment QoL 9 I have to talk very quietly QoL 10 I feel vulnerable when I'm on my own QoL 11 I get dizzy spells most days HRQL

  23. 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

  24. 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

  25. Response rates for test-retest postal administration UK versions

  26. Reproducibility of needs-based QoL instruments UK versions

  27. 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 Reproducibility of QoL-AGHDA

  28. Known groups validity for the QLDS * Hamilton Depression Rating Scale

  29. Median QLDS score Responsiveness of the QLDS:General practice population Effect size >2

  30. Effect sizes for QLDS and SF-36

  31. Change in QoL of parents of children with atopic dermatitis Moderate Mild Almost clear

  32. Needs-based QoL measures

  33. Treatment compliance and QoL

  34. 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

  35. 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 Generating disease-specific utility

  36. 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 RGHQoL scenario

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

  38. 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 Cross disease comparisons

  39. 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 Cross disease utility

  40. 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 Co-calibration of disease specific QoL instruments

  41. 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

  42. Percentage of "Yes" responses for common items by diagnosis group

  43. 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) Item banking

  44. 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

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