The outcome of intensive care is related to patient selection and case
-mix. Especially when assessing QOL, the results should be interpreted
in the context of age and the cause of intensive care admission. Only
a few QOL studies so far have databases which are large enough to cha
racterize the outcome in specific patient groups. The influence of pre
existing chronic diseases should be taken into account as well. A far
more difficult issue is how to screen for differences in socioeconomic
background. Problems in physical functioning seem to be common among
ICU patients in general, but among younger patients the psychosocial p
roblems are also dominant. While the QOL after intensive care as compa
red with reference values may be better perceived among older patients
, the previously healthy and younger ones tend to experience more limi
tations. The reason for intensive care presumably has impact on the pa
ttern of convalescence. A better understanding of the natural history
of recovery from critical illness may help to identify those patients
who need more intensive rehabilitation.