The concept of Quality of Life (QoL) is essential for patients and a key consideration in health technology assessment (HTA). Yet, it remains a complex concept to define and measure.

While most people agree that both length of life and quality of life matter, what constitutes a “good” quality of life can vary significantly between individuals. As a result, multiple approaches and instruments have been developed to capture this diversity in patient experience and values.

This dilemma is well expressed by statistician John Tukey:

‘It is often much worse to have good measurement of the wrong thing especially when, as is so often the case, the wrong thing will in fact be used as an indicator of the right thing than to have poor measurement of the right thing.’