New Knowledge

Quality of life (QOL) is a term that cannot be measured by a single variable and has substantial overlap with concepts such as social functioning, disability, social support and wellbeing.²⁴ It is a wide-ranging concept that encompasses the effects that the psychological state, beliefs, relationships and the environment may have on a person’s health.^30,107 It may include aspects of life not always directly related to health such as job satisfaction and standard of living. It has also been described as “the extent to which objective human needs are fulfilled in relation to personal or group perceptions of subjective well-being”.¹⁰⁸ Quality of life measures have been applied in screening for psychosocial problems in individual patient care; population surveys of perceived health problems; medical audits; outcome measures in health services or evaluation research;

clinical trials and cost-utility analyses. The term “health-related quality of life” is a domain of quality of life and it focuses on health and aspects of quality of life relevant to it.¹⁰⁹ HRQOL measurement therefore attempts to capture QOL in the context of one’s health and illness.

Assessing HRQOL is an attempt to explore the functional effects of an illness and its management on a patient, as perceived by the patient. It specifically explores the extent to which one’s usual or expected physical, emotional, and social well-being are affected by a medical condition or its treatment.³⁰ Researchers have further theorized HRQOL outcomes/ domains in two dimensions:

objective assessments of functioning or health status against more subjective perceptions of health.

Thus, though the objective dimension defines the patient’s degree of health, the patients’ subjective perceptions and expectations translate the objective assessment into the actual QOL experienced.

It is therefore possible for two people with the same health status to have very differences in quality

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of life.¹¹⁰ It has been emphasized however, that HRQOL measures are not a substitute for disease outcomes, but are adjunct to them.¹¹¹ Summarily, HRQOL adds value to clinical practice because it can be applied to track changes in functional status over time for chronic illness, evaluate and monitor treatment effects, improve patient provider communication and adherence to medications.⁶⁵

The most common existing generic HRQOL models found in literature are those by Wilson and Cleary, and the modified version by Ferrans.^112–114 The Wilson and Cleary model has five well-defined domains; biological, symptoms, function, general health perception and overall HRQOL.

It proposes a classification scheme for different measures of health outcome by dividing the outcomes into five levels: biological and physiological factors, symptoms, functioning, general health perceptions, and overall quality of life. This framework also proposes specific causal relationships between the levels, linking traditional clinical variables to measures of HRQOL. As one moves from left to right in the model, one moves outward from the cell to the individual to the interaction of the individual as a member of society.¹¹⁵

Figure 2.4.1: HRQOL conceptual model by Wilson and Cleary showing relationships among measures of patient outcome

24 Patient-related

factors Socio-demographic

Age Sex Marital Status Educational level

Socio-economic status Income Employment Status Lifestyle/ Behaviour

Smoking status Illness-related factors

Symptoms at presentation physiological psychological

Number of symptoms Delay before

presentation Disease severity MDR diagnosis*

Degree of Gene-Xpert or Sputum positivity Lung function changes Type of TB

Pulmonary Extra-pulmonary*

Class New Relapse*

Co-morbidities HIV

Sickle cell*

Treatment-related factors

Adherence Adverse drug reactions Mild Severe Requiring hospitalization

Concurrent treatment for other diseases Hypertension Diabetes Mellitus HIV drug interactions Period of treatment

Health-Related Quality of Life

Physical health Psychological Social

Environment (WHOQOL-BREF)

Treatment Outcomes Cured/Completed Treatment Failure Lost to follow up Death

Environment Physical

Living conditions Pollution

Social environment Stigma

Social Support Health worker attitudes

Figure 2.4.2: Conceptual Framework for HRQOL in Patients with tuberculosis

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Figure 2.2 describes the conceptual framework for understanding HRQOL in patients with TB.

It was adapted based on the Wilson and Cleary model. The framework shows how different individual and environmental characteristics can combine with different diseases and treatment variables to predict Health-related quality of life. The first objective is to measure HRQOL and its different sub-domains as shown in figure 2.2. There are also several factors that interact namely, patient-related factors, illness-related factors, treatment-related factors and the environment which may be associated with health-related quality of life. This framework was created based on literature search of variables that were found to be associated with quality of life as well as the examination of conceptual theories of quality of life described above. For example, studies that examined the relationship between HRQOL level and differences in socio-demographic characteristics, effects of illness as well as changes in the social and family environment.¹¹⁶