Evaluating Patient-Based Outcome Measures - NIHR Health ...

Improvement in QoL was used to compare
intermittent and continuous chemotherapy
treatment in women with advanced breast cancer
and found in favour of a continuous strategy
(Coates et al., 1987). QoL has been used in a
similar manner to compare different treatment
strategies in prostate cancer (Keoghane et al.,
1996), small-cell lung cancer (Gower et al., 1995)
and acute myeloid leukaemia (Stalfelt, 1994).
Olsson et al (1986) compared metoprolol to
placebo in patients with myocardial infarction
and found that the treatment improved QoL.
The effect of drug treatment on QoL has also
been evaluated in heart failure (Bulpitt, 1996)
and hypertension (Applegate et al., 1994). QoL
was also used as the primary outcome in a clinical
trial to compare surgical techniques used in hip
arthroplasty, which found no difference between
cement versus cementless total hip arthroplastry
(Rorabeck et al., 1994).
When investigators also need to obtain evidence
of the overall value of a health care intervention
in a way that permits comparison with other interventions,
whether in the same treatment area or
across areas, then outcomes that provide evidence
of the overall value to patients of outcomes in the
form of utilities are required. The most widely
known form of summary value of treatments for
comparative purposes is the QALY (Torrance,
1986). The debate about the validity of QALY is
beyond the scope of this review and is considered
elsewhere (Carr-Hill, 1989; Carr-Hill and Morris,
1991; Coast, 1992; Drummond, 1993; Nord, 1993;
Petrou et al., 1993; Smith and Dobson, 1993).
In relation to the current review, it is increasingly
argued that data for such analysis should be
obtained from patients participating in a clinical
trial in order that they provide responses
to utility-based assessments as well as other
data on health status.
Patient-based outcome measures may also be used
in non-randomised research designs, although the
interpretation of results will be more complex, as is
the case with any other form of outcome measure.
The overall objective of such uses is similar to that
of the randomised clinical trials, to detect differences
between groups experiencing different
interventions, but for one of a number of reasons
observational evidence is used (Ware et al., 1996a).
Patient-based outcome measures make such largescale
studies more feasible. It is beyond the scope
of the review to address broader questions as to
whether observational studies of outcomes of
interventions ever fully address issues of bias as
successfully as do randomised designs.
Health Technology Assessment 1998; Vol. 2: No. 14
In summary, the use of patient-based outcome
measures is far more developed than other applications.
That instruments have been shown to
have validity, appropriateness and other desirable
properties for use in randomised controlled trials
does not mean that they can be automatically
transferred to other uses. The third section of this
review primarily has in mind randomised clinical
trials and cost–utility studies associated with trials in
outlining the criteria in terms of which patientbased
outcome measures should be evaluated and
chosen by investigators. However, there are two
other different types of use that have been argued
for patient-based outcome measures: assessing the
health of populations and as an aid in individual
patient care.
Assessing the health care needs
of populations
Health authorities and those responsible for
purchasing or providing health care are increasingly
expected to base their decisions about the
allocation of health care resources on evidence
(Scrivens et al., 1985; Kelly et al., 1996). Evidence
of health care needs comes from epidemiological
data. These may take the form of conventional
data on mortality and morbidity or be derived
from social, demographic and other indirect
measures that may indicate health needs. It has
been argued that patient-based outcome measures
provide a feasible and valid measure of health
status that complements existing approaches,
especially in so far as they focus upon felt and
experienced health problems (Hunt et al., 1985;
Ventegodt, 1996). Particularly if such assessments
are based on self-completed questionnaires with
proven acceptability, this approach offers the
possibility of using social survey methods to assess
aspects of health. Surveys have been conducted
on particular geographical populations (Curtis,
1987) and specific social groups such as ethnic
minorities and the unemployed (Ahmad et al.,
1989). A related use of patient-based outcome
measures is in combination with mortality data, for
example in measures such as health life expectancy,
and disability free life expectancy (Robine and
Ritchie, 1991). To be most useful in population
settings, a questionnaire, as well as being feasible
and acceptable, needs to provide information that
indicates needs for particular kinds of health or
other services. The main problem with this use is
that such instruments provide only general indications
of health problems. Although there is
growing evidence that poor scores on health status
measures may be associated with and predictive of
elevated rates of subsequent health service use and
mortality, they do not provide evidence of more
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