The concept of quality of life plays a key role in the modern medicine since it serves as a goal and gauge of treatment. The main trouble with it rests in that it belongs to the realm of 'ought' wherefore empirical data studying 'is' are of no help.
There is thus necessary to work with arguments borrowed from philosophy while philosophy has ever been dealing with this issue from its very beginning. This topic had in ancient Greece the name 'eudaimonia' and modern thinking rendered it usually as happiness or well-being.
These words do not mirror the entire content while the most appropriate equivalent of it is meaning of life worth pursuing by every human being. Yet meaning of life is veiled by sundry paradoxes and these paradoxes defy simple definition what makes application rather tough.
Moreover, the concept of quality of life must include also other factors like social, financial and natural environment as well as plain bodily health state. In any way, this background must be taken into account whenever the concept of quality of life is focused on.