Mohammad KA Basra; Muhammad Shahrukh


Expert Rev Pharmacoeconomics Outcomes Res. 2009;9(3):271-283. 

In This Article

Quality of Life

The WHO defines QoL as[16]:

"An individual's perception of their position in life in the context of culture and value systems in which they live in relation to their goals, expectations, standards, and concerns affected in a complex way by the person's physical health, psychological state, level of independence, social relationships and their relationships to salient features to their environment."

The term QoL is broad and is composed of several components or domains, such as physical well-being, psychological well-being, functional status, social functioning and health perceptions.[17] Health-related QoL (HRQoL) is a related term that denotes a state of an individual's QoL pertaining to health and disease and/or its treatment.[18]

The HRQoL is measured in the following circumstances[19,20,21]:

  • Clinical setup

  • Health population survey

  • Health services audit

  • Clinical research

  • Management decisions

  • Overall effectiveness of therapy

  • Political and financial purpose

The burden of skin disease is a very broad concept and there are different ways to measure it, such as QoL and HRQoL instruments, visual analogue scales (VAS) and utility measures, for example. The ever-increasing choice of tools makes it more likely that an instrument exists for most healthcare providers' decision-making needs. However, it is also important to have a basic understanding of the psychometric concepts to evaluate instrument for clinical or research uses.[22]

Measurement Properties of a Psychometric Instrument

The basic properties considered important for evaluating the accuracy of any measurement scale are[22]:

  • Precision

  • Reliability

  • Validity

  • Sensitivity to change

  • Practicality

Precision. The precision of an instrument is its capacity to detect small differences and is constrained by its level of measurement.[22]

Reliability. The reliability of a measure is the extent to which it consistently yields the same results in repeated applications on an unchanged population or phenomenon in a reproducible manner.[22]

Validity. This means whether an instrument of health status actually measures what it was intended to measure. The measure of HRQoL should demonstrate different types of validity such as face, content, criterion and construct validity.[22]

Sensitivity to Change. The instrument must also be sensitive, that is, it should be able to detect changes that occur in the study phenomena.[18] The questionnaire must be able to assess development in health status or HRQoL that occur as a result of medical treatments.

Practicality. The tool should be user-friendly and easy to use if one has to extract important information in a small fraction of time.[21]


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