Quality of Life Assessment Methods

There are many scholarly schools of thought regarding the assessment of a person’s quality of life (QOL). It is critical for health care professionals to take quality of life into account when establishing each patient’s goals of care and to use it as a guide for all care decisions.

When discussing QOL with patients, caregivers (both formal and informal), other health care personnel, and policy makers, health care professionals need to consciously avoid using language and assuming attitudes that suggest age bias, which negatively affects the patient's perception of what QOL could or should be.

Before diving into specific methods, it's important to understand some fundamental considerations in QOL assessment.

Barriers to Assessment

Assessing a patient's perspective on quality of life may be difficult for the following reasons:

• Such an assessment is not always taught or emphasized sufficiently in traditional medical education, which tends to be focused on diagnosis and prolongation of life.
• Quality of life is a subjective, individual experience, so decision models cannot be applied to individual patients.
• Quality of life is influenced by cultural factors (eg, for goals and values), and they must be assessed.
• Quality of life assessment and communication must account for each patient's literacy levels (including health literacy) and language skills.
• Assessing the patient’s perspectives on quality of life takes time because it requires thoughtful conversation between patient and health care professional, and there often is not enough time allotted for these in-depth conversations during traditional fee-for-service-based health care delivery models.

First, researchers often cannot define what they mean when they refer to the term QOL. A second issue is that people will vary regarding what they deem important for a quality life. For instance, one person may feel that a strong network of close relationships is necessary for a quality life.

First, QOL can be thought of as the sum of a range of objectively measurable life conditions. A second approach is to define QOL as a person’s satisfaction with the sum of these life conditions.

To illustrate with an example, one might consider the role of income level and how it may affect (a) quality of life conditions and (b) life satisfaction. Regarding (a), income size may be critical in contexts where one’s welfare is dictated by annual salary, such as in countries without strong social welfare systems. However, to a fairly non-materialistic person who has sufficient income to meet their basic needs, income size may only be a small contributor to life satisfaction (b).

According to a review by Gill and Feinstein (1994), there are at least 150 instruments in existence to measure QOL. Some investigators, particularly in the medical context, will apply a single-item assessment of QOL. In line with this, many researchers present a series of items (known as an instrument or index) to assess QOL. Sometimes, such instruments may contain several subscales that tap into QOL across various domains, such as relationships, living conditions, professional life, and so forth.

The first option is to present the results of each of the subscales individually, forming a kind of profile. It is clear to see that domains such as these, mirror several of the domains in which a person may rate their QOL.

Method of assessing QOL

People can assess their own quality of life or more specifically their own health. Also known as self-assessed health or self-perceived health, self-rated health (SRH) refers to a single-item health measure in which people rate the current status of their health on a scale ranging from excellent to poor.

SRH has been proved a reliable predictor of mortality and disability by a series of national and international analyses (1).

During assessment, health care professionals should be careful not to reveal their own biases. Determining a patient's preferences is usually possible; even patients with dementia or cognitive impairment can make their preferences known when health care professionals use simple explanations and questions. Having family members present when discussing preferences of a patient with cognitive impairment is recommended.

Commonly Used Tools for Assessing Quality of Life

Some of the most commonly used and well-validated patient-reported tools for assessing quality of life include the following:

• EQ-5D (EuroQol [2]): This standardized instrument measures mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. It can also be used to calculate quality-adjusted life-years for cost analysis to help evaluate health care interventions and policies.
• SF-36 (Short Form Health Survey [3]): This tool consists of 36 questions evaluating physical, mental, and social health (eg, vitality, pain, physical function). A physical and mental composite summary scores can be generated, providing a single score that measures health-related quality of life.
• PROMIS (Patient Reported Outcomes Measurement Information System [4]): PROMIS instruments consist of algorithm-generated patient questionnaires that gather and quantify health domains relevant to patients (eg, pain, fatigue, physical function, emotional distress, social health). The data gathered are available to researchers online.
• FACIT (Functional Assessment of Chronic Illness Therapy [5]): This collection of quality of life questionnaires for certain chronic conditions (eg, cancer, HIV, multiple sclerosis) can be used to help assess physical, social, emotional, and functional well-being.
• WHOQOL-BREF (6): This tool is an abbreviated 26-item version of the World Health Organization (WHO) quality of life assessment, which includes physical/psychologic health, social relationships, environment, overall quality of life and general health.

These surveys have been validated internationally, translated into many languages, and successfully implemented in various clinical settings and patient populations.

Emerging data sources (eg, wearable devices, data derived from electronic heath records by machine learning) are expected to provide more continuous, empirical metrics to supplement self-reported quality of life information.

Quality of Life Assessment in Healthcare

Specific Quality of Life Scales

Here are some specific examples of QOL scales and their characteristics:

1. Quality of Life Scale (QOLS):

   In developing the QOLS, Flanagan began by collecting responses to interview questions from 3,000 Americans, representing a broad range of ages, races, and backgrounds. A copy of the full scale with scoring instructions can be accessed from the clinical assessment platform ePROVIDE.

   The QOLS assesses various factors, including:

   • Freedom from sickness, physical and mental fitness, avoiding accidents and health hazards.
   • The presence of relatives with whom one feels belonging.
   • Having close friends with whom one shares activities, interests, and views.
   • The presence of guiding principles in one’s life.
   • Interesting, worthwhile work at home or in one’s formal job.
2. McGill Quality of Life Questionnaire (MQOL):

   Published in 1996, the McGill Quality of Life Questionnaire (MQOL) was designed to assess the QOL of patients facing life-threatening illnesses. Unlike the QOLS, several of the domains in the MQOL-Expanded (MQOL-E) are assessed using multiple items.

3. HRQOL Questionnaire:

   The HRQOL Questionnaire combines three separate modules to assess perceptions of HRQOL. It is widely used by health professionals and was designed to bridge the gap between disciplines, such as sociology, psychology, and economics, about the drivers of QOL. Rather than consisting of subscales, this questionnaire is made up of three modules. The first module is a compact and validated set of four items to assess HRQOL broadly. The final module is called the Healthy Days Symptoms Module. Several studies have been published evidencing the validity of the HRQOL.

4. WHOQOL-BREF:

   Another trustworthy measure of QOL has been developed by The World Health Organization (WHO). The WHOQOL-BREF is widely used for comparing indices of QOL across cultures.

The WHOQOL-BREF uses a two-week reference period to capture current quality of life while allowing for day-to-day fluctuations. This timeframe is long enough to provide a stable assessment yet short enough to detect meaningful changes during treatment. However, the developers acknowledge that different timeframes may be necessary depending on the clinical context. For chronic stable conditions like arthritis or back pain, extending to four weeks might better capture the typical experience without being overly influenced by good or bad days.

For conditions with cyclical patterns - such as chemotherapy cycles, menstrual-related disorders, or bipolar disorder - timing of assessment becomes crucial. Administering the measure at the same point in each cycle ensures comparability. In acute psychiatric admissions or intensive interventions, some clinicians use the standard two-week frame initially, then shift to asking about “since your last assessment” for frequent monitoring.

The perception of time also varies across cultures and age groups, which should be considered when interpreting responses.

Choosing the Right Scale

In many cases, scholars will lean toward choosing scales that are highly cited in reputable journals when designing research. You will also want to choose a scale that avoids what is known as floor and ceiling effects.

A floor effect is a problem in your data that occurs when most of your subjects score near the bottom of a scale. The trouble with either of these distributional characteristics is that your data will contain limited variance.

More importantly, by applying one of the assessments above, you will gain a better insight into the effect that factors like pain, illness, or mental health conditions may have on your clients’ daily functioning.

Assessment Tool	Description	Key Features
EQ-5D (EuroQol)	Standardized instrument measuring mobility, self-care, usual activities, pain/discomfort, and anxiety/depression.	Used for calculating quality-adjusted life-years.
SF-36 (Short Form Health Survey)	36-item survey evaluating physical, mental, and social health.	Generates physical and mental composite summary scores.
PROMIS (Patient Reported Outcomes Measurement Information System)	Algorithm-generated questionnaires gathering data on health domains relevant to patients.	Data available to researchers online.
FACIT (Functional Assessment of Chronic Illness Therapy)	Collection of questionnaires for specific chronic conditions assessing physical, social, emotional, and functional well-being.	Condition-specific questionnaires available.
WHOQOL-BREF	Abbreviated 26-item version of the WHO quality of life assessment.	Includes physical/psychologic health, social relationships, and environment.