outcome measure. They examined the relative effectiveness of home versus hospital care
for patients with a range of problems, including hip replacement, knee replacement and
hysterectomy. Quality of life was assessed using tools such as the SF36 and disease-
specific measures, and the results showed no differences between the two groups at a
three-months follow-up. Therefore, the authors concluded that if there are no significant
differences between home and hospital care in terms of quality of life, then the cost of
these different forms of care becomes an important factor.
Problems with using quality of life as an outcome measure
Therefore, research uses quality of life as an outcome measure for trials that have dif-
ferent designs and are either focused on specific illnesses or involve a range of problems.
However, there are the following problems with such studies.
Different studies use different ways of measuring quality of life: generalizing across
studies is difficult.
Some studies use the term ‘quality of life’ while others use the term ‘subjective health
status’: generalizing across studies is difficult.
Some studies report results from the different measures of quality of life, which are in
the opposite direction to each other: drawing conclusions is difficult.
Some studies report the results from quality of life measures, which are in the
opposite direction to mortality or morbidity data: deciding whether an intervention is
good or bad is difficult.
Quality of life as a predictor of longevity
Most research using quality of life explores its predictors and therefore places this
variable as the end-point. However, it is possible that quality of life may also be a pre-
dictor of future events. In particular, quality of life could be seen as a predictor of
longevity. To date, there are no studies that have directly addressed this possibility,
although there are some studies which indirectly suggest an association between quality
of life and longevity. For example, several studies indicate that mortality is higher in
the first six months after the death of a spouse, particularly from heart disease or suicide
(e.g. Kaprio et al. 1987; Schaefer et al. 1995; Martikainen and Valkonen 1996). It is
possible that this could relate to a lowering of quality of life. Further, some studies
suggest a link between life events and longevity (see Chapter 14). Perhaps these links
could also be explained by quality of life. Therefore, quality of life may not only be an
outcome variable in itself but a predictor of further outcomes in the future.
TO CONCLUDE
This chapter has explored the different ways of measuring health status. In particular, it
has examined the use of mortality rates, morbidity rates, measures of functioning,
MEASURING HEALTH STATUS 393