1

Quality of Life Definitions• 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 (WHO, 1993).

• Health-Related Quality of Life (HRQOL): the experience and importance of different domains of health that are affected by disease and treatment.

2

Why is QOL important?

• QOL is widely perceived to have substantial potential as an endpoint in medical and health outcomes research.– Used to evaluate pharmacologic agents in

clinical trials of cancer, arthritis, heart failure, and hypertension.

– Used to adjust measures of effectiveness for therapeutic decision-making and to plan allocation of resources.

3

• QOL and HRQOL refer to the physical, psychological, and social domains of health, seen as distinct areas that are influenced by a person’s experiences, beliefs, expectations, and perceptions.

• These domains can be measured by (1) objective assessments of functioning or health status, or (2) subjective perceptions of health.– The patient’s subjective perceptions and

expectations translate that objective assessment into the actual quality of life experienced.

4

QOL Conceptual Model(Wilson & Cleary, 1995)

•

5

HRQOL Conceptualization(Ware, 2003)

Participation(role &social)

MentalComponent

PhysicalComponent

6

Conceptual Scheme of the Domains and Variables Involved in a QOL Assessment (Testa & Simonson, 1996)

7

Individual health perceptions

• 1971 study of Canadian steel workers: simply being “labeled” as hypertensive → more absenteeism

• Suggests strong influence of labelingon perceptions of one’s own health– Do patients adopt “sick role”?

R.Brian Haynes, McMaster University

9

• A patient-reported outcome (PRO) is a measurement of any aspect of a patient's health status that comes directly from the patient, without the interpretation of the patient's responses by a physician or anyone else

• PRO measurements are sometimes confused with quality of life measurements. – Quality of life is a broad concept referring to all aspects of a person's well-being. – PRO instruments are used to measure quality of life, but they also can focus much

more narrowly—for example, on a single symptom, such as pain.• Some manufacturers of drugs or medical devices are interested in showing,

and claiming, that a treatment improves patients' quality of life. Such a claim would imply an evaluation of the impact of a treatment on all aspects of a person's well-being. – Quality of life measurements assess not just the physical consequences of disease,

such as symptoms and decreased function, but also the effect of disease on a person's emotional state, feelings, coping behaviors, and self-identity (psychological functioning) and on a person's ability to interact well with others (social functioning).

10

• Despite the interest in examining effects of drugs on quality of life, the FDA has rarely allowed a claim that a product improves quality of life because it has been very difficult to show such broad effects from drugs that are directed at specific symptoms.

• But a health-related quality of life (HRQOL) claim would be considered by the FDA if the PRO instrument reliably captured the impact of treatment on the most important aspects of HRQOL. HRQOL represents an individual's perceptions of how an illness and its treatment affect, at a minimum, the physical, mental, and social aspects of his or her life.

• HRQOL PRO instruments have been developed for specific diseases, and the FDA has permitted HRQOL claims on the label of certain drugs. For example, the label of the asthma drug Advair, an FDA-approved inhaled bronchodilator, is allowed to carry an HRQOL claim because, says Burke,  "the drug sponsor successfully measured an impact of Advair on not only the symptoms of asthma but also on physical, social, and psychological functioning in asthma patients." The Advair label states, in part:

• The subjective impact of asthma on patients' perception of health was evaluated through use of an instrument called the Asthma Quality of Life Questionnaire (AQLQ). Patients receiving Advair … had clinically meaningful improvements in overall asthma-specific quality of life ...

11

• Measure efficiency or effectiveness of interventions

• Assess quality of care (patient outcomes)• Estimate a population’s needs• Improve clinical decisions• Understand causes and consequences of

differences in health• Outcome in chronic diseases• Emphasis on chronic care

12(McHorney, 1997)

199519901950 19851955 19651960 1970 1975 1980

Applications for Health Status and Health-Related Quality of Life

Measures

13

Choosing a QOL Instrument• Instruments that are useful for monitoring

patient care in clinical practice . . . • Capture types of outcomes that are important to

patients• Are short and easy to administer• Differentiate between patients with chronic

conditions and healthy controls• Differentiate among patients who have different

diseases or conditions• Are sensitive to severity differences across patients

with the same condition and to severity differences in individual patients over time

• Are sensitive to treatment effects over time

14

Using an Existing QOL Instrument

• Determine your purpose and decide whether to use a generic or disease-specific instrument, or a combination of the two.

• Understand the purpose and objectives of the instrument.

• Understand the conceptual basis of the instrument.• Know how the instrument was developed.• Assess reliability and validity!

15

Generic Measures• Broadly applicable across types and severities of

disease, across different medical treatments or health interventions, and across demographic and cultural subgroups.

• Designed to summarize a spectrum of the concepts of health and QOL that apply to many different impairments, illnesses, patients, and populations.

• Designed to capture physical, psychological, and social aspects of health.

• Can be used to measure health along the entire range of health from well-being to disability.

16

• Sensitive to picking up distinctions between individuals who differ by clinical status, but may be insensitive to clinically important, disease-specific changes.

• Make it possible to compare types of outcomes characterizing a particular patient group with types of outcomes characterizing another patient group or a nonpatient, comparison group.

• May provide generalizability and/or information that is important to third-party payers and policy makers.

17

36-Item Short-Form Health Survey (SF-36)

• 8 Domains• Physical

functioning• Role limitations due

to physical health problems

• Social functioning• Bodily pain

• General mental health (psychological distress and well-being)

• Role limitations due to emotional problems

• Vitality (energy/fatigue)• General health

perceptions

18

SF-36 Sample Questions1. In general, would you say your health is:

2. During the past 4 weeks, how much has your physical health or emotional problems interfered with your social activities (like visiting friends, relatives, etc.)?

3. How much bodily pain have you had during the past 4 weeks?

All of the time

Most of the time

Some of the time

A little of the time

None of the time

Excellent Very good Good Fair Poor

None Very Mild Mild Moderate Severe Very severe

HRQL instrument — interpretation issues

– What is trivial? What is clinically meaningful?

20

Disease-Specific Measures• Designed to assess specific diagnostic groups or

patient populations, and to tap the domains of greatest interest for that particular condition.

• Often, the goal is to measure responsiveness or “clinically important” changes.– Changes that clinicians and patients think are

important, have been detected with an intervention of known efficacy, or are related to well-established physiologic measures (e.g., grip strength for arthritis patients).

• Changes in disease-specific measurements may correlate with changes in clinical measurements of disease activity, such as blood pressure, providing information that is important to clinicians.

21

• Closely related to areas of importance to the clinician.

• More sensitive than a generic measurement to changes in disease-related symptoms or treatment side effects.

• Because they focus on a specific disease, they are more likely to have sensitivity to smaller amounts of change related to a health condition.

22

Arthritis Impact Measurement Scales

• Physical disability• Mobility• Physical activity• Dexterity• Activities of daily living• Ability to conduct household activities• Pain

23

Kidney Disease Quality of Life Instrument

• Symptom/problems• Effects of kidney

disease• Burden of kidney

disease• Cognitive function• Quality of social

interaction

• Work status• Sexual function• Sleep• Social support• Dialysis staff

encouragement• Patient satisfaction

24

Combined Measurement Approach

• The use of both generic and disease-specific measurements may provide the most informed picture of patient outcomes.

• A wider range of changes in functioning and/or well-being may be captured.

• May be especially important for monitoring outcomes that have multiple dimensions and etiologies, such as sleep disturbance.

25

• The intention when using both types is not to measure the same concepts as a generic measure with specific reference to a medical condition, but to capture the additional, specific concerns of patients with the condition that are not contained in the generic measures.

26

Reliability• Represents the consistency of the measure

obtained.• The process of measurement must yield

values that are consistent or remain similar under constant conditions, even in an extended series of repeated assessments.

• Types of Reliability:– Internal Consistency– Test-retest– Parallel forms

– Interrater– Intrarater

27

Validity• Refers to the extent to which an instrument

measures the intended concept,or what it is intended to measure.

• Validity relates to the extent to which scores result in the accurate classification of objects in regard to their domain status.

• Once the instrument is constructed, it is essential to subject it to validity testing.

• When indicated, the measure is revised to enhance its validity.

28

Types of Validity

• Content validity• Criterion-related validity• Convergent validity• Construct validity