**3. Measuring health-related quality of life**

Adequate HRQOL measurement instrument should capture all the effects that disease and its treatment have on the physical, emotional, social, and mental dimensions of an individual [19]. An ideal instrument would be comprehensive, reliable, and of proven validity and would facilitate comparisons between groups of subjects with different illnesses and within the same group receiving different modes of treatment. The extracted HRQOL measures must be converted into a numerical value for proper utilization.

There is no one ideal tool of measuring HRQOL, and therefore, multiple different instruments have been developed.

Most of these instruments use a series of questions to assess quality of life indirectly. These questions are defined as "items." Each item is then given a numerical value, based on a predetermined scale. Most researchers measure each quality-of-life domain separately, by asking specific questions pertaining to its most important components.

HRQOL instruments can be subdivided into categories based on whether the tool is global or domain specific. Three major domains comprise global HRQOL: the physical domain, the social domain, and the psychosocial or mental domain.


Many schemes have been developed to assess QOL in individuals with end-stage renal disease. Here, we will briefly describe the most common tools used in assessing HRQOL in studies involving patients under treatment by OL-HDF.

**Table 1.** Components of the Short Form-36 (SF-36).

#### **3.1. Kidney Disease Quality of Life (KDQOL) Short Form-36 (SF-36)**

**3. Measuring health-related quality of life**

converted into a numerical value for proper utilization.

social domain, and the psychosocial or mental domain.

involving patients under treatment by OL-HDF.

Role-physical (RP) Limited ability to work because of physical health

Social functioning (SF) Physical and emotional symptoms

Role-emotional (RE) Emotions limit daily function and work

Mental health (MH) Feels nervous and depressed all the time

**Table 1.** Components of the Short Form-36 (SF-36).

asking specific questions pertaining to its most important components.

Severe limitations in physical activity, including bathing and dressing

severely limit normal social activities

have been developed.

126 Advances in Hemodiafiltration

Physical functioning

(PF)

Ref. [25].

Adequate HRQOL measurement instrument should capture all the effects that disease and its treatment have on the physical, emotional, social, and mental dimensions of an individual [19]. An ideal instrument would be comprehensive, reliable, and of proven validity and would facilitate comparisons between groups of subjects with different illnesses and within the same group receiving different modes of treatment. The extracted HRQOL measures must be

There is no one ideal tool of measuring HRQOL, and therefore, multiple different instruments

Most of these instruments use a series of questions to assess quality of life indirectly. These questions are defined as "items." Each item is then given a numerical value, based on a predetermined scale. Most researchers measure each quality-of-life domain separately, by

HRQOL instruments can be subdivided into categories based on whether the tool is global or domain specific. Three major domains comprise global HRQOL: the physical domain, the

Many schemes have been developed to assess QOL in individuals with end-stage renal disease. Here, we will briefly describe the most common tools used in assessing HRQOL in studies

**Domain Meaning of low score Meaning of high score Number of**

Bodily pain (BP) Severe limiting pain No pain or limitations due to pain 2 General health (GH) Perceives health as poor Perceives health as excellent 5 Vitality (VT) Feels tired and worn out all the time Feels full of pep and energy all the time 4

limitations

other activities

Performs vigorous activity without

Physical health does not limit work or

No physical or emotional limits to

Emotions do not interfere with daily

Feels peaceful, happy, and calm all the

normal social activities

function or work

time

**questions**

10

4

2

3

5

The Kidney Disease Quality of Life (KDQOL) instrument is a self-report questionnaire consisting of 134 items [20]. It has the SF-36 as its generic core and is supplemented with items of relevance to the HRQOL of dialysis patients. Disease-specific items assess symptoms/ problems, effects of kidney disease on daily life, burden of kidney disease, cognitive function, work status, sexual function, quality of social interaction, and sleep. Included are also items relating to social support, encouragement from dialysis staff, patient satisfaction with care, and a global rating of health. A more practical shorter version, the KDQOL-SF, was developed later in view of the length of the original one. The KDQOL-SF includes the SF-36 supplemented with 43 disease-specific items from the domains identified in the original version [21].

The KDQOL-SF is easy to administer and has been validated and used widely with hemo‐ dialysis (HD) patients. KDQOL-SF became the most widely used QOL measure for ESRD patients. It was developed in the USA for dialysis patients and has been translated into several languages, to be used in several studies involving dialysis patients [22–24].

The SF-36 Health Survey can be self-reported or obtained with the help from a health profes‐ sional in patients unable to complete the survey. The SF-36 contains only 36 items, through which it evaluates eight health concepts of HRQOL. The eight health concepts are physical functioning (ten items), role limitations resulting from physical problems (four items), role limitations caused by emotional or personal problems (three items), social functioning (two items), bodily pain (BP) (two items), energy/fatigue (four items), emotional well-being (five items), and general health (GH) perceptions (five items). In addition, there is one single item that provides an indication of perceived change since 1 year. Two additional components can be calculated from the SF-36, and they are the physical component summary (PCS) and the mental component summary (MCS). A higher score is associated with a more favorable health status. Components of the SF-36 are depicted in **Table 1**.

#### **3.2. The Kidney Disease Questionnaire (KDQ) of Laupacis et al. (Canada) [26]**

In 1992, Laupacis developed this tool which is disease-specific designed for use in chronic HD patients. The KDQ consists of 26 items in five dimensions: physical symptoms (six items), fatigue (six items), depression (five items), relationships (six items), and frustration (three items). The physical symptoms dimension of the KDQ is patient specific. The six physical symptoms that are most important to each subject are identified and used to assess that dimension. Patients are asked to identify their specific physical problems, next to questions regarding frustration, depression, and well-being. Patients are asked to grade their complaints on a scale ranging from one (severe) to seven (none). The KDQ is designed for use only in patients with ESRD on HD treatment.

#### **3.3. The Euro Quality of Life Group (EQ-5DTM) questionnaire**

The EQ-5DTM measures health-related quality of life in five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Scores for the five dimensions are converted into preference weights by using country-specific value sets drawn from the general population [27].

This instrument is rather new; therefore, only few country-specific value sets are available.

#### **3.4. The CHOICE Health Experience Questionnaire (CHEQ) [28]**

This is a patient-reported measure of HRQOL developed for use in the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease (CHOICE) Study [29]. The authors have defined it as "the value assigned to duration of life as modified by the impairment, functional states, perceptions, and social opportunities that are influenced by disease, injury, or policy." This instrument was developed to evaluate the effectiveness of alternative dialysis prescrip‐ tions. It supplements SF-36 survey in measuring HRQOL for patients with ESRD. It is sensitive to differences in dialysis modality and dialysis dose. The selection of HRQOL domains to be utilized was based on literature review, analysis of focus groups, and survey of dialysis providers and patients. In order to arrange domains and items identified, a representative sample of 136 dialysis patients rated each item for frequency and distress. The survey yielded 22 HRQOL domains that included 96 items: eight generic domains in the SF-36 (health perceptions, physical, social, physical and emotional role functions, pain, mental health, and energy), eight additional generic domains (cognitive functioning, sexual functioning, sleep, work, recreation, travel, finances, and general quality of life), and six ESRD-specific domains (diet, freedom, time, body image, dialysis access, and symptoms).
