As medicine has moved on from a ‘‘life preserving’’ to a
‘‘health promoting’’ science [95], the concept of Quality
of Life (QoL) has become increasingly important in the
study of medical conditions, their impact and their outcome [18]. The QoL concept has been defined in many
ways, but all definitions, to a greater or lesser extent,
emphasize the ideal state as one of general well-being in
which an individual’s day-to-day functioning, across a
wide range of domains, is unencumbered by the potentially adverse impact of disease or disorder. Leidy et al.
[44] defined QoL as ‘‘an individual’s subjective perception of the impact of health status, including disease and
treatment, on physical, psychological, and social functioning.’’ This is compatible with the WHO QoL group’s
description of QoL as ‘‘the individuals perception of their
position in life, in the context of culture and value systems in which they live, and in relation to their goals,
expectations, standards and concerns’’ [91]. Almost all
QoL definitions and measures include physical, social and
psychological domains (although similar domains are
often labelled differently). A cognitive domain is also
commonly included [24]. Although QoL is influenced by
many proximal (i.e., family, friendship) and distal (socioeconomic and cultural) forces, illness is one of the most
potent influences [24]. In addition to the effects of
physical illness on QoL, there is now substantial evidence
that mental illness has major impact [7, 50, 70].