2. What is quality of life?


2. What is quality of life?

There is no single definition of Quality of Life (QoL), though there have been many attempts to define it. Similar to their definition of health, the World Health Organisation (WHO) definition is among the more comprehensive definitions. The WHO defines quality of life as:

‘…individuals’ perceptions 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 incorporating in a complex way the person's physical health, psychological state, level of independence, social relationships, personal beliefs and their relationship to salient features of their environment’.1

The WHO suggests that quality of life encompasses several key areas, called ‘domains’. These domains have topics (called ’facets’ by the WHO) incorporated within them. See Table 1 below.

Note that the majority of domains of quality of life listed in the table include aspects that may be affected by health and/or use of health technologies to treat a medical condition, while the final domain (personal values and beliefs), although important, may not be as frequently affected. This narrower focus on the quality of life related to an individual’s perceived state of health is called health-related quality of life (HRQoL)’, in the table designated by the first four domains.

An attempt at defining HRQoL could be:

"The extent to which one's usual or expected physical, emotional and social well-being are affected by a medical condition or its treatment" [1] . This definition incorporates the two widely accepted aspects of quality of life: subjectivity and multidimensionality [2].

Because the WHOQOL focuses upon respondents' "perceived" quality of life, it is not expected to provide a means of measuring in any detailed fashion symptoms, diseases or conditions, nor disability as objectively judged, but rather the perceived effects of disease and health interventions on the individual’s quality of life. The WHOQOL is, therefore, an assessment of a multi-dimensional concept incorporating the individual's perception of health status, psycho-social status and other aspects of life

Patients, payers or providers who want to understand the value of a treatment could include the last domain, or assume it won’t change and then focus more specifically on aspects directly affected by health technologies.

As you can see from Table 1 below, HRQoL is multi-dimensional (contains multiple items and domains) including physical, psychological, fnctional, and social domains related to a person’s perception of quality of life affected by health status. HRQoL measurement therefore will attempt to capture QoL in the context of one’s health and illness addressing these domains.


Table 1: WHO domains and facets of quality of life 


Facets incorporated within the domains

 1. Physical health (HRQoL)

  • Energy and fatigue*
  • Pain and discomfort
  • Sleep and rest

 2. Psychological health (HRQoL)

  • Positive feelings
  • Thinking, learning, memory, and concentration
  • Self-esteem
  • Body image and appearance
  • Negative feelings

 3. Level of independence (HRQoL)

  • Mobility
  • Activities of daily living
  • Dependence on medication or treatments
  • Working capacity

 4. Social relationships (HRQoL)

  • Personal relationships
  • Social support
  • Sexual activity**

 5. Environment

  • Physical safety and security
  • Home environment
  • Financial resources
  • Health and social care: accessibility and quality
  • Opportunities for acquiring new information and skills
  • Participation in and opportunities for recreation and leisure
  • Physical environment (pollution, noise, traffic, climate)
  • Transport

 6. Spirituality / Religion / Personal beliefs

  • Religion
  • Spirituality
  • Personal beliefs

  Adapted from World Health Organisation WHOQOL-100. 2  


*Tiredness may result from any one of a number of causes, for example illness, problems such as depression, or over- exertion. The impact of fatigue on social relationships, the increased dependence on others due to chronic fatigue and the reason for any fatigue are beyond the scope of questioning, although they are implicit to the questions in this facet and facets concerned specifically with daily activities and interpersonal relationships

**The WHO explains sexual activity as follows:

This facet concerns a person's urge and desire for sex, and the extent to which the person is able to express and enjoy his/her sexual desire appropriately. Sexual activity and intimacy are for many people intertwined. Items regarding sexual activity, however, enquire only about sex drive, sexual expression and sexual fulfilment, with other forms of physical intimacy being covered elsewhere.

Items do not include the value judgements surrounding sex, and address only the relevance of sexual activity to a person's quality of life. Thus the person's sexual orientation and sexual practices are not seen as important in and of themselves: rather it is the desire for, expression of, opportunity for and fulfilment from sex that is the focus.The term HRQoL (also called HrQL, HRQOL , HRQL, QOL ) has been widely adopted and promoted within the HTA community. The term HRQoL is often used interchangeably with the generic term ‘quality of life’ as well as terms like:

  • self-reported health
  • patient-assessed outcomes
  • patient-reported outcomes
  • person-reported outcomes
  • patient outcomes
  • outcomes

The terms ‘patient health status’ and ‘functional status’ have also been used to mean HRQoL, despite the fact that these measures do not strictly require information from the patient’s perspective – that is, they are not necessarily patient reported outcomes (PROs). Similarly, there also exist outcomes derived from information from parents, providers or caregivers about their perceptions of how a patient’s health-related quality of life should be judged. These have recently been labelled proxy- or observer-reported outcomes (ObservROs) and include clinician-reported outcomes (ClinROs).

However, HRQoL represents a subjective appraisal of the impact of illness or its treatment; individual patients with the same objective health status can report dissimilar HRQoL due to unique differences in expectations and coping abilities. As a result, HRQoL should be measured from the individual's viewpoint rather than that of outside observers (i.e., caregivers or healthcare professionals) and is a PRO.

EUPATI in its documents uses the term health related quality of life (HRQoL) to avoid different interpretations.

[2] Aaronson NK. Quality of life: what is it? How should it be measured? Oncology (Williston Park) 1988; 2:69.