Models and definitions of quality of life

PoCoG Quality of Life Webinar 20th August 2015

Dan Costa

(we will commence at 5 past the hour)

“Does [insert intervention] improve quality of life?”

What does this mean?

PART I

How is quality of life defined?

Where to look

1. Books

2. Research articles (empirical and theoretical)

3. Models

4. Health organisations

1. Books

“Quality of life (QoL) is an ill-defined term... most people, in the Western

world at least, are familiar with the expression ‘quality of life’ and have an intuitive

understanding of what it comprises.”

1. BOOKS

“Concepts of health often lack clarity... The term ‘quality of life’ also has

many meanings.”

1. BOOKS

“a vague and ethereal entity, something that

many people talk about, but which nobody clearly knows what to do about.”

1. BOOKS

“QOL in the Benthamite tradition is essentially contentment, whereas QOL in the Aristotelian

sense in a meaningful and fulfilling life.”

1. BOOKS

2. Research articles (empirical and theoretical)

“a kind of umbrella under which are

placed many different indexes dealing with whatever the user

wants to focus on.”

Feinstein, A.R. (1987). Clinimetric perspectives. Journal of Chronic Diseases, 40, 635-640.

2. ARTICLES

“Quality of life in clinical medicine represents the functional effect of an

illness and its consequent therapy upon a patient, as perceived by the

patient.”

Schipper, H., Clinch, J.J., & Olweny, C.L.M. (1996). Quality of life studies: Definitions and conceptual issues. In: Spilker B

(ed). Quality of life and pharmacoeconomics in clinical trials (2nd ed). Philadelphia: Lippincott-Raven Publishers.

2. ARTICLES

but seriously…

“HRQOL refers to the extent to which one’s usual or expected

physical, emotional, and social well-being are affected by a medical

condition or its treatment.”

Cella, D. (1995). Measuring quality of life in palliative care. Seminars in Oncology, 22, 73-81.

2. ARTICLES

“HRQOL is a multidimensional construct encompassing perceptions of both

positive and negative aspects of dimensions, such as physical, emotional, social, and cognitive functions, as well as

the negative aspects of somatic discomfort and other symptoms produced

by a disease or its treatment.”

Osoba, D. (1994). Lessons learned from measuring health-related quality of life in oncology. Journal of Clinical Oncology,

12(3), 608-616.

2. ARTICLES

“…the functional effect of an illness and its consequent therapy upon a patient, as perceived by the patient.”

“…the extent to which one’s usual or expected physical,

emotional, and social well-being are affected by a medical condition or its treatment.”

“…a multidimensional construct encompassing perceptions of

both positive and negative aspects of dimensions, such as physical, emotional, social, and cognitive functions, as well as

the negative aspects of somatic discomfort and other symptoms produced by a disease or its treatment.”

2. ARTICLES

3. Models

3. MODELS

World Health Organization (2002). Towards a Common Language for Functioning, Disability and Health.

Geneva: WHO.

3. MODELS

Wilson, I.B., & Cleary, P.D. (1995) Linking clinical variables with health-related quality of life: a conceptual model of

patient outcomes. Journal of the American Medical Association, 273(1), 59–65.

3. MODELS

Page 60 “The concept of quality of life is distinct from health, though related to it.” “Economic, political, cultural, and spiritual factors may affect overall quality of life, but are generally not considered to fall under the purview of physicians and health care systems.” “Health status and HRQL can refer to different concepts, but in this article we use the terms interchangeably.”

Wilson and Cleary

Elements vs. determinants of quality of life

Ferrans, C.E., Zerwic, J.J., WIlbur, J.E., & Larson, J.L. (2005).

Conceptual model of health-related quality of life. Journal of Nursing Scholarship, 37(4), 336-342.

So what are the elements and what are the determinants?

It depends on the definition.

Costa, D.S.J, & King, M.T. (2013). Conceptual, classification or causal: models of health status and health-related quality of life. Expert Reviews

in Pharmacoeconomic Outcomes Research, 13(5), 631-640. Costa, D.S.J. (2015). Reflective, causal, and composite indicators of quality of life: a conceptual or an empirical distinction? Quality of Life Research,

9, 2057-2065.

3. MODELS

“Both the multitude and persons of refinement... conceive “the good life” or

“doing well” to be the same thing as “being happy”. But what constitutes happiness is a matter of dispute... Some say one thing and

some say another, indeed very often the same man says different things at different times: when he falls sick he thinks health is

happiness, when he is poor, wealth.” Aristotle, Nichomachean Ethics

3. MODELS

4. Health organisations

“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 and concerns. It is a broad ranging concept affected in a complex way by the person’s physical health, psychological state, personal beliefs, social relationships and their

relationship to salient features of their environment.”

4. HEALTH ORGANISATIONS

“HRQL is a multidomain concept that represents the patient’s general perception of the effect of illness and treatment on physical,

psychological, and social aspects of life.”

“A PRO [patient-reported outcome] is any report of the status of a patient’s health

condition that comes directly from the patient, without interpretation of the patient’s response

by a clinician or anyone else.”

4. HEALTH ORGANISATIONS

Other thoughts

Quality of life vs. unmet needs HRQoL questionnaires: perceived direct impact of illness and

its treatment. Needs questionnaires: extent to which consequent needs for

supportive care are currently met.

Conceptually and empirically similar?

Colagiuri, B., King, M. T., Butow, P. N., McGrane, J. A., Luckett, T., Price, M. A.,

& Birney, D. P. (2012). A comparison of the FACT-G and the supportive care needs survey (SCNS) in women with ovarian cancer: Unidimensionality of

constructs. Quality of Life Research, 21, 887-897

Working definition

Quality of life:

what quality of life instruments measure

PART II

How is quality of life assessed?

Method of assessment

1. Descriptive questionnaires

2. Single item

3. Utility instruments

1. Descriptive questionnaires

1. DESCRIPTIVE QUESTIONNAIRES

1. I have a lack of energy 15. I feel sad

2. I have nausea 16. I am satisfied with how I am coping with my illness

3. Because of my physical condition, I have trouble meeting the needs of my family 17. I am losing hope in the fight against my illness

4. I have pain 18. I feel nervous

5. I am bothered by side effects of treatment 19. I worry about dying

6. I feel ill 20. I worry that my condition will get worse

7. I am forced to spend time in bed 21. I am able to work (include work at home)

8. I feel close to my friends 22. My work (include work at home) is fulfilling

9. I get emotional support from my family 23. I am able to enjoy my life

10. I get support from my friends 24. I have accepted my illness

11. My family has accepted my illness 25. I am sleeping well 12. I am satisfied with family communication about my illness 26. I am enjoying the things I usually do for fun 13. I feel close to my partner (or the person who is my main support)

27. I am content with the quality of my life right now

14. I am satisfied with my sex life

FACT-G

FACT-G

QLQ-C30

SF-36

FLIC SIP

NHP

MHIQ QLI

MQOL

AQEL ASC

COOP DLQI

GIQLI

WHOQOL GLQ-8

IBCSG LSQ

LTQL

MSAS

MDASI

POS

PC-QoL

PROSQOLI

QLACS

RSCL

SF-12

SIP

SCI

TQ

UBQ-C

et cetera

1. DESCRIPTIVE QUESTIONNAIRES

1. DESCRIPTIVE QUESTIONNAIRES

Reflective or formative?

Anxiety Quality of life

Wind down

Agitated

Touchy

Can’t relax

Sleep

Daily activities

Work

Reflective indicators comprise a scale

Formative (or, more specifically, causal or composite) indicators

comprise an index Elements or determinants?

2. Single item

How would you rate your overall quality of life?

2. SINGLE ITEM

Easy for respondents to answer

Low burden

Does not (explicitly) confound elements and determinants

2. SINGLE ITEM

Advantages

Quite nicely

High test-retest reliability Moderate-high responsiveness

de Boer, A.G.E.M., van Lanschot, J.J.B., Stalmeier, P.F.M., van

Sandick, J.W., Hulscher, J.B.F., de Haes, J.C.J.M., & Sprangers, M.A.G. (2004). Is a single-item visual analogue scale as valid,

reliable and responsive as multi-item scales in measuring quality of life? Quality of Life Research, 13, 311-320.

2. SINGLE ITEM

How do single items perform compared to multi-item scales?

Interpretation and measurement error

What are respondents thinking when they answer the question?...

2. SINGLE ITEM

Problems

“Even with haemorrhoids I think my quality of life is pretty good.”

“That could be interpreted broadly to include

everything or it could relate only to the cancer. Seeing as everything else I’ve said is related to the cancer I should be consistent and relate this to the

cancer.”

“My life is really, really good. Except I’m renovating…”

2. SINGLE ITEM

Problems

3. Utility instruments

Weighted by preferences

i.e., Descriptive instruments ask “how severe”

or “how often”?

Utility instruments do the same but apply a preference weighting

3. UTILITY INSTRUMENTS

Quantity vs. quality

Quality of life

Quantity of life

10 years

5 years 30%

70%

Survival time

Quality of life

0.3 0.35

Treatment 1 Treatment 2

3. UTILITY INSTRUMENTS

Administer a small number of items (like a descriptive instrument) to patients in a

clinical trial

The items have previously been valued by a large sample so that each item has a utility

weight

General population usually provides valuations

3. UTILITY INSTRUMENTS

Multi-attribute utility instruments

Health state = particular

combination of levels

After valuation,

each item level gets a utility decrement

weight

3. UTILITY INSTRUMENTS

e.g., EQ-5D

35 = 243 health states

Quality of life = aggregate of effects

Are these items sensitive enough?

3. UTILITY INSTRUMENTS

EQ-5D Mobility Self-care Usual

activities Pain/ discomfort

Anxiety

1 0 0 0 0 0

2 0.069 0.104 0.036 0.123 0.071

3 0.314 0.214 0.094 0.386 0.236

What items go in? Who decides and using what criteria?

Implicit definition of quality of life:

“patient perception of the effects of illness and treatment as modified by various factors

chosen by a specific research team and valued by a large number of other

people, most of whom have not experienced the illness.”

3. UTILITY INSTRUMENTS

Problem

What about an assessment of the effects of illness and treatment weighted by what’s important to the

patient?

How do we assess this? Ask the patient to list what is important to them, then

assign weight, then aggregate?

OR…

Solution?

“the value assigned to duration of life as modified by the impairment, functional states, perception and social

opportunities that are influenced by disease, injury, treatment, or policy”

How would you rate your overall quality of life?

As an outcome of a clinical trial?

As an item in a questionnaire?

As an umbrella term for patient-reported outcome measures?

As a name for a field of research?

What value does the term “quality of life” have?