How do I measure quality of life (QoL)?

Clinicians and researchers are often interested in measuring quality of life. Living with diabetes is known to impair both the quality and quantity of life, which by itself can affect motivation and self-confidence to continue the diabetes care.

Before selecting a measure it is necessary to define what you mean by quality of life. Many clinicians and researchers refer to measuring QoL but when we ask them about that in more detail, they are often referring to other aspects of the individual’s experience, e.g. emotional well-being, treatment satisfaction, health status. For QoL, there is not a common definition, but there is a general consensus that it is:

  • multidimensional (physical, psychological and social),
  • subjective (QoL means different things to different people),
  • dynamic (QoL will change over time and as a result of various factors) Because of these characteristics, measuring QoL is complex.

The best way of assessing it is to ask individuals about what is important for their QoL, and how they evaluate the quality. Not all aspects of QoL are equally important for each individual, or relevant in different circumstances. Although this qualitative method is preferred, for the purpose of clinical trials or clinical practice, quantitative (questionnaire) measures are needed. A variety of measures have been developed for the general population and more specifically for people with diabetes. However, many questionnaires have been used to assess QoL when they actually measure another concept entirely. This has led to inappropriate use of questionnaires and misinterpretation of the results. Some studies have used questionnaire measuring one aspect of quality of life (e.g. health status) or assessing a different concept (e.g. depression, treatment satisfaction). The results may still be very relevant and interesting but are not informative with regards to QoL.

Jane Speight and colleagues have published a systematic literature review on this topic, which discusses the measures most frequently used to assess QoL in diabetes research .

Speight J, Reaney M, Barnard K. (2009). Not all roads lead to Rome—a review of quality of life measurement in adults with diabetes. Diabetic Medicine, 26(4), 315-327 .